This page describing diabetes mellitus (DM) is very thorough and will require some study if you want to understand it fully. There is a different kind of diabetes, called diabetes insipidus, which is not the same disease. In general, when most people say a pet or a person has diabetes, or if they also say sugar diabetes, they are refurring to diabetes mellitus.
Sugar diabetes, more correctly know as diabetes mellitus (DM), is a complex disease that is difficult to control, particularly in cats. Proper treatment requires a commitment on your part, usually for the life of your pet. It is well worth the effot in most cases because response to treatment is usually quite rewarding.
By definition, DM is a persistent hyperglycemia and glycosuria due to an absolute or relative insulin deficiency. By the time you are done with this page you will understand what all of this means.
You will also learn that some of the parameters of DM in animals are similar to humans, and many parameters are not, so be careful of extrapolating any experience you have between the two. DM can occur in many different species like birds and Guinea Pigs, although it is most commonly diagnosed in dogs, and especially cats.
Obesity is a big reason pets get DM. Fat is not just fat, it causes inflammation, leads to the rise of insulin resistance, which means your pet gets DM and does not respond well to insulin treatment. Most obese cats are prone to be what is called prediabetic. It all has to due with a hormone called amylin elevated in the bloodstream of overweight cats.
Other facts influence diabetes mellitus. An important one is dental disease. The infection in the mouth can make it difficult to regulate a diabetic cat. We have a detailed page on dental disease to learn more about this.
Chronic pancreatitis can also predispose your cat to getting diabetes mellitus. We have a page on this (which includes inflammatory bowel disease) to learn more about pancreatitis.
You can go far in preventing DM by keeping your pet at a normal weight, and feeding your cat a food that is higher in protein and lower in carbohydrates. Routine exams, that include blood panels and urinalyses that both monitor glucose, are important as your pet ages.
We have a summary page on DM if that suits your needs better than this detailed page.
It will help if you learn these medical words because they will be used on this page:
- euglycemia – normal blood glucose level
- hypoglycemia – low blood glucose level
- hyperglycemia – high blood glucose level
- glycosuria – high glucose in the urine
- ketonuria – ketones in the urine[/column]
- polyphagia – excess appetite
- polyuria – excess urinating
- polydypsia – excess drinking
- PU/PD – polyuria and polydypsia
- DKA – diabetic ketoacidosis
The ability to use a food source for energy is critical to the success of any species, therefore nature has very sophisticated mechanisms to regulate this process. These mechanisms are extremely complex, and only those mechanisms that relate to diabetes mellitus will be summarized for the sake of simplicity.
In response to a decreasing blood glucose level the appetite center in the brain is stimulated and hunger ensues. A meal is then eaten, which consists of fats, carbohydrates, and proteins, in different percentages. When these fats, carbohydrates, and proteins are broken down by the digestive system and absorbed into the bloodstream, they are used by the body for various functions. The main function of the carbohydrates is eventual conversion to an energy source in the form of glucose, the primary energy source for all cells in the body. Some of this glucose is stored in the liver in the form of glycogen, which is released and converted back to glucose when cells need energy in-between meals.
Carbohydrates can be complex or simple. Complex ones are bread and pasta, simple ones are lactose (the carbohydrate in milk). When these carbohydrates are absorbed in the bloodstream through the intestines they are converted to glucose by the liver. The simple ones, like lactose, are rapidly converted and will immediately raise the blood glucose level. The more complex carbohydrates take longer to be metabolized to glucose by the liver, as a result they raise the blood glucose level more slowly. This point becomes important when treating both hyperglycemia and hypoglycemia.
Once in the bloodstream the glucose that circulates throughout the body is available for use by all cells as their primary energy source. These individual cells cannot absorb this glucose that passes by in the bloodstream unless the hormone insulin is circulating in the bloodstream at the same time. Insulin causes a chemical reaction in the cell wall that allows the glucose to enter the cell. The only cells in the body that do not need insulin to absorb glucose are specific brain cells.
Insulin originates in a group of cells called the islets of langerhams that are located in the pancreas. Insulin comes from the beta cells in the islets. It is secreted into the bloodstream in response to an increase in glucose in the bloodstream, a normal occurrence after a meal is eaten. The higher the glucose level the greater the amount of insulin secreted. Since the absorption of simple carbohydrates will cause a more rapid increase in blood glucose there will be a more rapid increase in insulin secreted. The complex carbohydrates will cause a more gradual rise in the insulin level. This fact becomes important in feeding a diabetic patient.
The normal physiology is even more complex. Insulin also has a large effect on fat and protein metabolism. In addition, the pancreas also secretes a hormone called glucagon in response to a decreasing blood glucose level. Glucagon originates from the alpha cells in the islets, and its role is to help the liver convert glycogen back to glucose. As can be expected, glucagon will increase the blood glucose level, and counteracts the blood glucose lowering effects of insulin. Insulin and glucagon work in a negative feedback loop that allows for a very refined system to keep the blood glucose level at an optimal level for the energy requirements of each individual cell. The liver is a major part of this loop, acting as a blood glucose buffer to keep the blood glucose at optimum levels. This is a highly refined process that is fine tuned over thousands of years and works extremely well.
In general, brain cells do not need insulin to utilize glucose. A specific area of the brain, called the appetite center (in the hypothalamus), monitors the amount of glucose that circulates in the bloodstream. The lower the blood glucose level in the cells in the appetite center the greater the appetite. Unlike most of the brain cells, the ability of glucose to enter the cells of the appetite center is dependent upon insulin. In diabetes mellitus, with its lack of adequate insulin in the bloodstream, these appetite center cells don’t monitor glucose levels properly, thinking the blood glucose is low. As a result, the pet develops polyphagia to correct for this perceived problem. The additional food that is then eaten further increases the blood glucose level.
The pancreas does more than secrete insulin and glucagon into the bloodstream. It is the primary source of enzymes that are secreted into the small intestines (not bloodstream this time). These enzymes are secreted in response to the presence of food in the digestive tract, and are the primary way that many nutrients are broken down and absorbed by the intestines into the bloodstream. The way these energy sources are acted upon by the enzymes, and how they are eventually utilized by the liver, are also factors that effect the blood glucose level.
To further complicate the picture, epinephrine (adrenaline), cortisol (cortisone) and growth hormone also influence the blood glucose level.
This is a picture of the pancreas of a cat. It is adjacent to the beginning of the small intestine called the duodenum. The pancreas is the pinkish tissue directly under the cylindrical duodenum. For such a small organ it has an important job.
Now that you are an expert at normal physiology, lets learn what happens when the normal mechanisms described above go wrong. This is called pathophysiology. What causes this pathophysiology, leading to a lack of insulin production by the pancreas? It is multi-factorial, and includes:
- Genetic predisposition
Obesity and a lack of physical activity are predisposing factors, especially in cats.
The relative lack of insulin causes the blood glucose to go abnormally high. Normal blood glucose in a dog or cat varies from 80 to 150, but can temporarily go much higher (300-500 or more) in stressful situations. When the blood glucose is consistently high, as seen in diabetes mellitus, several negative effects occur.
Many diabetic cats will start having a rise in their blood glucose levels before the onset of symptoms, and before the beta cells in the pancreas lose their abilitly to secrete insulin. If we can catch this early, insulin secretion might possibly be restored. This emphasizes the importance of yearly exams with a blood panel and urinalysis to screen for this.
Inadequate insulin levels force the cell to perform its functions with alternative sources of energy besides glucose. This causes problems for the organ that is made up of these cells, and eventually will lead to significant disease and the complications that occur in untreated diabetes mellitus.
The cells of the body (except most brain cells) are deprived of their primary source of energy. This means they do not function at optimum efficiency. Since they are starved of glucose they need to rely on other sources of energy, namely fat and amino acids. These are not as good an energy source as glucose in the long run.
To utilize amino acids as an energy source the body needs to break down protein. A large part of this conversion occurs in the protein in muscles cells. As this conversion from protein to amino acids progresses the body loses its muscle mass and weight loss occurs.
Metabolism of fat as an energy source is a normal response when cells do not receive adequate glucose for their energy. In the short term this process is highly advantageous. Fat has twice as much calories as proteins and carbohydrates, so it is a concentrated source of energy in the short run. If the fat metabolism process goes on for a prolonged period of time it becomes detrimental, and leads to the buildup of byproducts from fat metabolism. The main byproduct is a compound called ketones.
The ketones that build up in this process change the pH of the blood, further dehydrate a pet, interfere with other metabolic processes, and cause fatty infiltration of the liver. Ketones also cause vomiting, which leads to further inappetance and additional dehydration and electrolyte imbalance. Further inappetance causes the cells to use even more fat as an energy source, causing an uncontrollable spiral, and sometimes even death. Any diabetic pet presented with ketones in its urine is a medical emergency. These pets have what are termed diabetic ketoacidosis, abbreviated as DKA.
In addition to the liver, the kidneys are another important organ in this disease. The primary role of the kidneys is to filter the blood. As the blood passes through the kidney filters essential nutrients are returned to the bloodstream and waste products are excreted through the urinary system. Glucose is one of the many molecules that is returned to the bloodstream after it has passed through the kidney filters. Once the glucose exceeds 200 mg per deciliter (this varies by species, cats tend to be higher) in the bloodstream though, the kidneys can no longer selectively return all of this glucose back into the bloodstream. This is called “exceeding the renal threshold”, and is a very important part of diabetes mellitus.
As a result, glucose spills into the urinary tract and bladder in excessive quantities. Since glucose attracts water (called the osmotic effect) it pulls fluid out of the pet and causes polyuria. To compensate for this excess urination the pet drinks more water, and now has polydypsia. It now has the symptoms we abbreviate as PU/PD. Eventually it causes dehydration when the pet can’t drink enough water to keep up with the increased urination. In addition, the excess urination pulls important electrolytes out of the bloodstream like sodium and potassium, which leads to lethargy and weakness. The loss of glucose also depletes the body of its primary energy source, so additional weight loss occurs. To further add to a diabetic pet’s woes, the excess glucose that builds up in the bladder feeds bacteria that can cause a urinary tract infection.
Why the pancreas stops secreting adequate levels of insulin is a mystery. There is a strong correlation for diabetes mellitus to occur in cats that previously had an episode of pancreatitis. This makes sense because the pancreas is the source of insulin. Yet, many cats that have diabetes mellitus had no apparent pancreatitis in the past. In some pets the immune system attacks the beta cells in the islets and deposits a compound called amyloid which, makes the beta cells unable to secrete insulin. This amyloid, which contains a protein called amylin, is thought to play a significant role in non-insulin dependent diabetes (your will learn about this soon) because amylin is toxic to the cells in the islets of langerhams.
Another factor involved in non-insulin dependent diabetes is peripheral insulin resistance. This resistance plays a significant role in obese pets, which is a major predisposing role in the development of insulin. Genetics is also involved-genetics cannot be controlled, but obesity can.
Elevated levels of thyroxine, which occurs in feline hyperthyroidism, can also be a factor in insulin resistance.
So what does all of this mean? To summarize all of this pathophysiology:
- Peripheral insulin resistance, due to obesity and/or the protein amylin found in amyloid, causes chronic stimulation of insulin production in the pancreatic beta cells.
- Impaired insulin secretion causes insulin and amylin to accumulate in beta cells in the pancreas.
- The high levels of amylin in the beta cells allows amyloid to deposit, further disrupting the ability of these cells to produce and regulate insulin. As the problem progresses non-insulin dependent diabetes eventually progresses, and at some point in time, the symptoms of diabetes mellitus appear.
The pancreas can get a tumor called an insulinoma. In this case the pancreas secretes too much insulin and the blood glucose hovers at dangerously low levels. This problem is rare in most animals except for the ferret
Most people are familiar with the classification scheme used in human medicine. Even though the disease is similar in people and pets, the human classification scheme does not always correlate with diabetes mellitus in cats. Differentiating between Type I and Type II in cats can be difficult.
Has similarities to insulin dependent or juvenile onset diabetes mellitus. Most commonly occurs in middle aged cats. Insulin is needed to treat the problem. This is also known as insulin dependent diabetes mellitus (IDDM).
Similar to adult onset or non-insulin dependent in humans. Obesity is a significant risk factor. Insulin is not needed in all cases. Type II cats can become Type I cats when exposed to significant stress. Fortunately, when the stress is resolved they can revert back to Type II. This is also known as non-insulin dependent diabetes mellitus (NIDDM).
Diabetes can occur secondary to other problems. Some of these problems include hormone imbalances and reactions to medications. A medication called Ovaban, a hormone used to treat numerous cat ailments, can cause diabetes if used excessively.
The classic signs of a cat or dog with diabetes mellitus are PU/PD. These signs of excess drinking and urinating are subtle at the beginning stages of the disease and are easily missed. This is especially true in outdoor cats who do most of their urinating outside, and dogs that urinate outside also.
Other symptoms include weakness, an increase in appetite, occasionally a decrease in appetite, weight loss, lethargy, and rarely, vision problems due to cataracts (this problem is more common in dogs). Cats with a severe liver problem associated with this disease might have icterus (jaundice).
An affected cat might even walk abnormally on the rear legs (called plantigrade posture) due to nerve problems as a consequence of the elevated blood glucose level. It is also known as diabetic neuropathy, and tends to occur as the disease progresses. The best way to prevent it is to keep the blood glucose level as close to normal as possible.
This is what the abnormal (plantigrade) posture looks like
These are also the symptoms of other diseases commonly seen in dogs and cats, and can only be differentiated by diagnostic tests. These other diseases include, but are not limited to, hyperthyroidism, kidney disease, cancer, liver disease, Cushing’s disease and adverse reaction to medications.
The yellow discoloration to these gums is icterus (jaundice). It is commonly, but not always, caused by liver disease.
Symptoms in dogs typically include:
- poor appetite
- weight loss
- cataract formation
Just like in cats, many dogs with diabetes mellitus were overweight at some time in the recent past.
Dogs with diabetes commonly have other diseases concurrently. They include:
- Urinary Tract Infections
- Cushing’s Disease
- Skin conditions
By the time a diagnosis of diabetes mellitus is made the disease process has usually been present for a significant period of time. When the disease process first started there were no obvious symptoms because of compensatory mechanisms in the body. As diabetes progresses these compensatory mechanisms lose their ability to maintain euglycemia. Eventually, symptoms of PU/PD and weight loss occur and your pet is brought in to be examined. This emphasizes the point that middle aged and older pets should have a routine blood panel and urinalysis every year once they reach 8.
This is a complex disease, and no specific set of symptoms tells us your pet has diabetes mellitus. It is important to follow the tenets of the diagnostic process closely when making a diagnosis of diabetes mellitus, especially since kidney disease and hyperthyroidism have similar symptoms. We will use the diagnostic process as an example of how we make this diagnosis:
Typically this disease is seen in obese cats that are middle aged or older, and more commonly in males (the opposite of dogs). Orange cats seem to get DM more often than other colors, but that could be because more of them are male. There is no specific breed predilection in cats.
Dogs are typically middle aged and older, with purebred dogs showing a higher incidence. Common breeds are:
- Miniature Schnauzers
- Labrador retrievers
- Miniature poodles
The classic signs of PU/PD, polyphagia, and weight loss occur in many cases, but not all. These signs depend on how well entrenched the disease process is before your pet is brought in for an examination. Sometimes the only thing an owner notices are accidents around the house in a previously housebroken cat.
A consistent finding is obesity in the recent past. This predisposes them to DM, and we sometimes call them pre-diabetic if obese enough. These obese cats need to be closely monitored for DM with fasting blood glucose tests, urinalysis, and fructosamine tests. You will learn about these tests in or diagnosis section.
Since this disease occurs in middle aged and older pets there can be other diseases occurring simultaneously. Some cats have a history of vomiting in the recent past, an indication that they might have had an episode of IBD (Inflammatory Bowel Disease) or pancreatitis. Some cats are borderline diabetics that have had a recent illness, stress, or adverse reaction to medication. There might also be blood in the urine or straining to urinate, an indication of a urinary tract infection.
Cats presented in DKA might have a history of abdominal pain and distention, vomiting, inappetance, and lethargy.
The findings of the physical exam depend on how severe the diabetes is, how long it has been present, what caused it, and if there are any other disease processes occurring simultaneously.
Many cats will have lost weight, yet they still could be obese. There might be dehydration, weakness, lethargy, an enlarged liver on abdominal palpation, and an acetone (juicy fruit) smell to the breath. Hypothermia and shock could be present in advanced cases and those with DKA.
The primary method of diagnosis is with a fasting blood panel and a urinalysis. The blood panel will reveal hyperglycemia (at least > 200 mg/dl) while the urine sample will reveal glycosuria. Not every case of hyperglycemia means a cat has diabetes mellitus. Cats that recently ate, or those that eat canned foods that are rich in sugar, might have blood glucose levels higher than the normal range. Cats that are stressed from a car ride, on cortisone, are in heat, on phenobarbital medication or hormone medications, might also have hyperglycemia.
Cats are unique in that their stress response can cause a tremendous rise (up to 4x normal) in the blood glucose. This is a common occurrence when we take a blood sample in a cat, and needs to be taken into consideration when we analyze a blood report. This stress induced response is a normal reaction to the release of epinephrine (adrenaline). It is a transitory response and will not persist like the hyperglycemia of diabetes mellitus. These cats sometimes need to adjust to a hospital environment before we are able to determine their true blood glucose level. It is always advised to check the blood sugar in dogs and cats after an 8-12 hour fast to give an accurate representation of the blood glucose level.
Here is a blood glucose report from our lab for a cat that does not have diabetes mellitus. The blood glucose is 317.
This cat has diabetes mellitus, its blood glucose is 390
How do we differentiate them when both are well above the normal range?
Diabetes mellitus is diagnosed when there is a persistent fasting hyperglycemia along with glycosuria, that is consistent with a history of PU/PD and polyphagia.
Other blood tests are sometimes used in this disease. The two more common ones are serum fructosamine and glycosylated hemoglobin. They are used to to distinguish stress induced hyperglycemia from diabetes mellitus, and to also monitor insulin therapy. They give us an indication of what the blood glucose level has been for the preceding weeks.
Fructosamine is formed when glucose reacts with amino acids that make up serum proteins like albumin, which is made by the liver. When the blood glucose is high, fructosamine also increases. Increased levels of fructosamine help confirm a diagnosis of diabetes mellitus, give us an idea of the presence of a persistent hyperglycemia, and help us monitor response to treatment.
Glycated hemoglobin (HbA1c), a tool to diagnose, monitor, and treat diabetes mellitus in people, is just start to get clinical application to dogs and cats with DM. This hemoglobin A1c test gives us a greater timespan to monitor glucose levels, up to 70 days in cats and 110 days in dogs, as opposed to fructosamine which monitors glucose levels for several weeks. The A1c test is is not affected by daily blood glucose fluctuations, exercise, diet, or the amount of insulin in the bloodstream. As this test is tested for consistency and become standardized and cost effective we will implement its use as another aid to monitor and treat or diabetic patients.
In addition to glucose in the urine and ketones, the urinalysis might indicate that a urinary tract infection is present. This is detected by a change in the pH of the urine, excess white or red blood cells, and bacteria. Even if these are not present a urinary tract infection can still be present. This is why we recommend a urine culture and sensitivity looking for bacteria.
This cat does not have ketonuria or an infection.
Most pets with diabetes mellitus have been ill for a longer period of time than most owners realize. The sooner we treat the better the outcome, and even with possible remission in some pets. This emphasizes over and over again the need for yearly exams (twice yearly for pets over 10 years of age) and blood panels to catch problems like diabetes mellitus early.
Treatment with insulin will not work overnight, and will take at least 30 days to get to proper regulation. During this time we slowly modify the dose of insulin, based as much on what you tell us how your pet is doing at home as much as our laboratory tests.
The goal of treatment is to resolve the symptoms of poor appetite, lethargy, and PU/PD without inducing hypoglycemia. Dogs tend to be easier to regulate than cats, although preventing cataracts from forming is difficult in the dog.
Some cases of diabetes mellitus in cats are not straightforward. An obese cat can have NIDDM in its normal, unstressed home environment. These cats are secreting insulin but in low levels. As long as they are in a stress-free environment they are able to maintain euglycemia. If they encounter a stressful situation, get sick, or are put on certain medications, their blood glucose will increase. If it goes beyond the renal threshold for glucose, PU/PD will ensue.
These cats are then brought to a veterinarian because of the PU/PD and diagnosed as having diabetes mellitus. They are put on insulin therapy and the problem improves. The problem occurs when these cats are returned to their normal environment and the problem that started the increased blood glucose in the first place (stress, illness, drugs) is now gone. In some of these cases these cats will now become hypoglycemic because they are being given insulin injections when they do not need them. Identifying these cats that have converted from insulin-requiring to non-insuin requiring NIDDM is difficult. This is one of the numerous reasons why diabetic cats should be brought to our hospital every 1- 3 months for a urinalysis and blood glucose curve.
If we start a cat on insulin injections, it’s weight is or becomes normal, and it responds well to insulin injections (especially glargine), we might have a cat in remission, which is our ultimate goal. In these cases we start lowering the insulin dose slowly, over several weeks to see if it still maintains a normal blood glucose.
Hypoglycemia, blood sugar that is too low, is your primary emergency problem. Symptoms to watch for include:
- Walking abnormally, like your pet is drunk
- Running into walls or circling
- Staring into space
All diabetic animals, especially cats, need to be closely monitored because urine and blood glucose levels are in a constant state of flux. Because of this you need to be in touch with your pet’s habits and observant of any changes. You also need to have Karo syrup available at all times for dogs and cats in case their blood sugar becomes low and they have problems. If you have no Karo syrup make up some sugar water and rub it on the gums.
Recent evidence suggests that feeding a high protein diet will help cats with diabetes mellitus. This higher protein diet mimics what a cat’s physiology has been used to for millenniums. It leads to less release of hormones that affect blood glucose levels. Some cats on high protein diets will need little if any insulin injections. Some cats that are on insulin injections to control their diabetes can actually go off insulin when put on a higher protein diet. The food we recommend is Hill’s M/D.
Dietary therapy might be all that is needed for the obese cat with NIDDM. A cat that is underweight from diabetes mellitus should not be put on a high fiber diet. Since this disease is prevalent in older cats this change in diet might be met with resistance. In these cases mix the higher fiber food with its regular diet to get some advantage of the higher diet. Do not feed foods that contain excess sugar like semi-moist canned foods.
Dogs tend to do well with Hills W/D. The most important thing to remember is consistency. Your dog and cat should be fed the food they like to eat, in the same amount, at the same time every day.
The goal of oral hypoglycemic medication is to minimize glucose absorption by the intestines and to also minimize the conversion of glycogen to glucose by the liver. They also help increase insulin secretion from the pancreas. Oral hypoglycemics need to be used early in the disease before the beta cells are exhausted. Since so many pets are brought to us well past that stage, they do not work as well as in humans.
They are used in cats that are not underweight, have negligible ketones in the urine, no indication of pancreatitis or no history of being on medication that could cause hyperglycemia. In conjunction with diet, oral hypoglycemics can sometimes help us differentiate NIDDM form IDDM. Cats with NIDDM will have significantly lower blood glucose levels when checked several days after initiating this protocol.
Some cats will vomit and might even develop hepatitis from oral hypoglycemics. Giving the medication with food helps minimize vomiting.
The main one used is Glipizide. Due to variable response and potential side effects it is not used often.
The thought of giving injections to your pet, especially a cat, can cause panic in some people. Keep in mind it is easier to give insulin injections with the tiny needle that is used, than it is to give a cat a pill. Once we show you how easy it is you will become an expert in no time. If you make it a positive endeavor, feeding around the same time, then a small treat, or a brushing or petting session just after the injection, it will be a positive experience for both of you.
There are many types of insulin that have been traditionally used to treat IDDM in our hospital over the decades. Unfortunately, the manufacture, Eli Lilly, has discontinued the production of many of its insulin products.
FastActing- Peaks in 2-4 hours Lasts 5-8 hours
IntermediateActing- Peaks in 8-12 hours Lasts 18-26 hours
ProlongedActing- Peaks in 16-24 hours Lasts 24-36 hours
Regular insulin is used initially to treat a cat or dog if it has DKA. Once the ketoacidotic state has been reduced we use the intermediate or prolonged lasting insulin. Your veterinarian will let you know which one might be most appropriate in your situation. Sometimes we need to try more than one type of insulin. What is just as important as the type of insulin used is the familiarity a doctor has with a specific protocol.
Most pets will need insulin given every 12 hours. This should coincide with a meal. You should decide ahead of time what insulin and feeding schedule works for you and your lifestyle because consistency is of utmost importance. The same thing goes for exercise since this affects insulin. Take your dog for the same type of walk at around the same time every day when possible to increase your chance of a good response to insulin injections.
For many years the insulin used to treat cats was derived from a beef-pork combination (90% beef and 10% pork) that was used in human diabetes mellitus. The pharmaceutical companies are now relying more on human recombinant (genetically engineered) insulin.
The goal of insulin therapy is to mimic naturally secreted insulin from the pancreas as closely as possible. This can be quite difficult in any species, let alone the cat. The dose of insulin and the type of insulin that is effective will vary from cat to cat and dog to dog. Once a proper dose is initially determined at some point in time in the future this dose will probably change.
Initially, insulin is dosed conservatively in order to see an individual dog and cat’s response and to minimize any chance of hypoglycemia. After your pet has been on this initial low dose we like to do a blood glucose curve to assess where we are, then make adjustments in dose accordingly.
An ideal blood glucose level for a diabetic cat is 65-220 mg/dl. Every cat is different, and we have diabetic cats with numbers lower than this, and numbers higher than this, that are doing fine. Your feedback on how your cat is doing and eating, and also how much it is drinking and urinating, is very important.
There are many different types of insulin used. We will go over the ones most commonly used:
Glargine and Detemir- Ultra long acting
Glargine, a human insulin has been successfully used in many cats. If used early in the course of the disease it is even possible to get a remission of the disease. Those cats that do go into remission need to be monitored and kept at an ideal body weight or they might have a recurrence of diabetes mellitus.
Glargine is more expensive than the other insulin’s used. This added expense might be worth it if your cats diabetes problem is actually cured of the problem. One of our doctors will discuss this with you and see if it is appropriate in your situation.
Glargine has been show to be effective in some cats, although its long term efficacy has not been proven yet in a large number of cats. The same holds true for Detemir. More studies with a large number of diabetic cats over a long period of time are needed.
PZI (Protamine Zinc Insulin)- Long acting
This is one of the more commonly used insulins in cats. It is usually given every 12 hours. We start with a dose of 1-3 units, and adjust as needed.
Vetsulin (Lente)- Intermediate acting
This insulin is approved for use in dogs and cats, and is one of the more common ones used, especially in dogs. Its use in cats is increasing due to good results. It is made from purified porcine insulin which has the same amino acids as canine insulin. Because of this there should be more effective regulation of blood glucose with less risk of anti-insulin antibodies. It is an intermediate acting insulin, and in some dogs once daily dosing is adequate. Cats usually need to be given their injections twice each day.
NPH (Neutral Protamine Hadedorn)- Intermediate acting
This has been the mainstay for treating diabetic dogs over many decades. It is still used, although we have been using Vetsulin much more frequently. It is not used in cats.
Ketoacidotic Diabetes Mellitus
Pets presented with DKA need immediate medical attention. They need regular insulin due to its ability to rapidly lower the blood glucose level. They also need fluids and electrolytes to correct dehydration, electrolyte imbalance, and acidosis (a change in the pH of the bloodstream). If this therapy is initiated too aggressively it might cause more harm than good. Our goal is to return your cat to a relatively stable state within the first 1-2 days after initiating this therapy.
Diabetic pets need to be slowly regulated (the correct dose of insulin needed). Many pets will take 4-8 weeks to find the proper level of insulin Most cats have well entrenched pathology that is not conducive to rapid change. The dose has to be given in small amounts initially to prevent hypoglycemia. It takes several days for a cat to respond to a change in dose. This initial regulation only gives us a starting point for your pet’s insulin dose since there will be numerous mitigating factors that will affect insulin levels when your cat returns home.
Initially we will use a low dose and have you administer the insulin at home at this dose for the next 7 days. After 7 days we will perform a glucose curve in our hospital over 10 hours. The blood glucose curve will give us an idea of how it is reacting to the type and amount of insulin we are using. Every pet is different, so this trending is needed to understand specifically how your pet will react. This curve will give us an accurate picture of just how high and how low the blood glucose is. This will then allow us to further refine the dose of insulin. We will do this glucose curve every 7 days, refining the dose each time, until we have achieved are desired level.
Any other problem your pet has, especially UTI’s (urinary tract infections) needs to be corrected for insulin injections to lower the blood glucose properly.
Our goal is to get the blood sugar level down to somewhere between 100-250 mg/dl. Some pets are regulated fine even if the blood glucose peaks at greater than 250 mg/dl. It is much better to have a pet that has a slightly high blood glucose level than to try and refine the dose so closely that hypoglycemia is risked.
To monitor your pets blood glucose we take frequent samples. To prevent the constant irritation from obtaining this blood sample we put a catheter into one of your cat’s veins. This eliminates discomfort and also minimizes the stress response.
This cat has jugular catheter — to learn more about catheters click here
The first step in the process of running a blood glucose test in our hospital involves taking blood from your pet and putting it on a special strip.
This cat’s blood glucose reading is 63 mg/dl. It is hypoglycemic at this point.
The typical pet eventually needs anywhere from 2-10 units given from once to twice daily. Of course this dose depends on the weight of your pet, the type of insulin used, its diet, its exercise level, and its individual response.
Even though these blood glucose checks are critical, your input as to how well your pet is eating, acting, and how much it is drinking and urinating, are just as important. If your pet is doing well in all these parameters then the blood glucose is being regulated.
It is imperative that you administer the precise amount of insulin required since small changes can have dramatic effects. Be consistent and give the insulin the same time and at the same location every day. If your pet is on twice daily insulin injections give each morning and evening dose at the same time every day. Always feed your pet in the morning prior to giving the insulin. If it does not eat its food skip the morning dose of insulin. If it eats only half of its food, give it only half of its insulin dose. Giving a normal dose of insulin to a pet that is not eating greatly increases the risk of hypoglycemia. You must always err on the side of hyperglycemia instead of hypoglycemia.
Most cats eat small bites of their food throughout the day. This might or might not work in a diabetic cat because of the manner in which the insulin that is administered peaks. If it does not work, feed your cat twice each day, feeding part of its daily meal when you give the insulin in the morning. Make sure it has access to this same food when the insulin level is peaking later in the day.
A record should be kept of your pet’s food intake to note any changes. The same thing holds for its water consumption. Marking this on a calendar weekly will give you important trends and give you a good idea if you are on the proper dose of insulin.
The actual administration of insulin is very straightforward. As a matter of fact, it is easier to give insulin injections at home than it is to give SQ (subcutaneous) fluids to cats that have chronic renal failure, a common feline problem. This is because an insulin injection takes 1 second to give, whereas fluids take 5-10 minutes. The technique used to give insulin injections or SQ fluids is the same- click here to view an actual demonstration of the administration of SQ fluids. When you are finished learning the proper technique return here to finish.
You will never be forced into doing something that makes you feel uncomfortable. While your cat is in the hospital with us you can observe how we give the insulin injections. One of our nurses will demonstrate its proper administration when we release your pet from the hospital. You can return to our hospital for assistance in giving the insulin at any time.
In order to simplify the process we will give you an insulin syringe that has been designed to be used with the specific type of insulin your pet requires. You will be giving insulin in a measurement called “units”, and not in ml (milliliters) or cc (cubic centimeters) as is commonly used in most syringes.
The use of injections is very simple. If we are using U-40 insulin, then we use a U-40 syringe. If we prescribe 2 units of insulin, draw up the insulin to the 2 mark on the syringe and give the injection. That’s all there is- no calculations are needed on your part.
Some cats require such a low dose of insulin that we have to dilute it for proper administration. A special diluent is needed for this, and diluted insulin should not be used longer than 2 months. A special syringe is sometimes used for dilute insulin.
This is what a U-100 syringe looks like. The needle is very small and sharp so your pet will not feel it during its injection.
Insulin should be kept refrigerated at all times to preserve its freshness. When you purchase it at the pharmacy bring an ice pack with you. Prior to use it should be gently warmed in your hands. Storing the insulin bottle on its side in the refrigerator will help in mixing.
Gently roll it (never shake it vigorously because excess bubbles will form) between your hands for 1-2 minutes to bring it to the proper temperature for administration.
Make sure you are in a relatively calm location when you give the injection. Hold the insulin bottle upside down and draw out slightly more than the number of units your cat requires. Tap the syringe a few times to remove any air bubbles-this aids in accuracy (a few tiny bubbles are OK). Push the plunger in the syringe slightly forward until you have the exact number of units you need to administer is in the syringe. Put the cap back on the syringe and put the insulin bottle back in the refrigerator. Do not reuse the syringe.
We will show you exactly how to do this in person, and give the first few injections for you until you get your confidence. In this picture you can see we have drawn 6 units into the syringe.
Give the injection in the scruff of the neck just as you would when giving SQ fluids described above. Your pet should not feel anything because the needle is so tiny and sharp. The whole process, from warming the insulin to giving the injections, should only take a couple of minutes. As you get confidence it is recommended to rotate your injection sites. We can shave a section of hair to make this whole process easier.
Improper administration of insulin is one of the most common causes for improper regulation. Please do not hesitate to contact us at any time for assistance in this vital procedure. Unless unavailable, only one person per household should be delegated to giving insulin.
The best way to monitor your pets blood glucose at home is to perform the blood glucose yourself. Ears and pads are areas in which a small prick will give sufficient amount of blood to run an in home blood glucose. In some cats this method of obtaining a blood glucose level is preferable to running a glucose curve in the hospital. This is because the stress of the car ride and the obtaining of blood several times while in the hospital can mislead us as to your cats actual blood glucose level.
Some of our clients use a home glucose kit to check their cats. It is easy to do once we show you, and gives a more accurate assessment of blood glucose levels at home than does the glucose in the urine. You only need a few drops of blood for the glucometer.
To use the glucometer you need to find an ear vein. You can see this one running horizontally under our nurses finger.
It is very simple to prick the ear with this machine and get your sample
After you place a drop of the blood in the green tip the machine will give you a blood glucose reading in a few seconds
Most people prefer to monitor the glucose in their pet’s urine because it is simpler. Monitoring of the glucose in your pets urine will give you at best a rough idea of its blood glucose level. There are significant limitations to home monitoring using urine glucose as a criteria. We do not recommend it.
Urine glucose measurements do not necessarily correlate with blood glucose measurements, the more important of the two. Also, if the blood glucose level is below the renal threshold a negative glucose in the urine cannot differentiate between euglycemia and hypoglycemia. If you note a significant amount of glycosuria consistently for several days your pet needs a blood glucose curve.
One of the ways the urine dipstick can be particularly helpful is in monitoring ketones. Occasional trace ketones is no cause for alarm. Consistent ketonuria in a cat that is not feeling well requires immediate veterinary care.
To help in the urine monitoring process your cat’s normal litter can be replaced with special litter that will not absorb urine. You can also use regular paper, newspaper, or even plastic wrap in the bottom of the cage. There is even a special litter that reacts with the glucose in the urine.
One of the more common urine dipstick kits is the Keto-Diastix. In addition to monitoring glucose it also monitors for ketones.
This is the chart on the Keto-Diastix bottle. The box to the far left is negative, which is the goal. The next box to the right is 100 mg/dl. Its OK to have this urine glucose value on occasion.
On the same bottle there is a chart to monitor for ketones in the urine. Your goal is to have negative with an occasional trace.
What is just as important as urine glucose is your subjective interpretation of how your pet is doing. If the original symptoms are greatly reduced then you are probably giving an accurate dose.
Determining the daily dose of insulin required at home is not an easy task. We have learned over the years that blood glucose determinations are variable, and that in many cases it is your perception at how well you pet is eating, how active it is, and how its drinking and urinating has decreased that is more important.
A more accurate blood test is the fructosamine level, which gives us an average of your pets blood glucose levels of the last 2-3 weeks, and is much less variable than individual blood glucose determinations. The fructosamine test is obtained at our hospital, and should be performed every 3 months after initial regulation.
Do not make any changes in insulin dose unless you talk with one of our doctors. Do not make daily changes in insulin doses either, wait 3 days to determine if the new dose is having any effect.
Warning signs that necessitate an exam and blood glucose curve in the hospital:
- Lethargy or significant increase or decrease in appetite
- Significant increase in drinking or urinating
- (100 mg/dl) or more glycosuria for > 2 days
- Significant ketones in urine for > 2 days
Long Term Care
It must be understood that in most cases insulin administration does not cure diabetes mellitus, it only controls it. As you learned above in the physiology section, the body has very sophisticated and refined mechanisms to keep the blood glucose at optimum levels. This can not be replicated easily by giving insulin. The exception to this is the occasional cat diagnosed early in the disease process and is not overweight. Glargine seems to be the best insulin to increase the chance of remission .
To minimize problems we should monitor your pets’s blood glucose level in the hospital and perform a urinalysis every 3 months. Since cats can exhibit an exaggerated stress response causing a profound hyperglycemia, a glucose curve is necessary to ensure accuracy. Every 6 months we should also perform a complete blood panel to look for changes in other organs caused by the diabetes. A urinalysis at the same time is needed to monitor for a UTI (urinary tract infection).
A further reason to run a complete blood panel every 6 months is to monitor routine age related changes like hyperthyroidism and kidney disease. Diabetes can also predispose your pet to high blood pressure (hypertension).
This long term monitoring is important for another reason. In almost every diabetic pet insulin requirements change, necessitating the need for close monitoring and communication with us. If your pet goes into heat (another reason to spay females and even neuter males) its insulin requirements might change. In some diabetic cats the problem goes away and they no longer have a need for insulin. Giving insulin to these cats can cause hypoglycemia, which if it is severe enough, can lead to seizures.
Complications of Diabetes
One of the more alarming, yet relatively rare side effects to insulin administration, is hypoglycemia. You should be ever vigilant about its appearance and always be ready to treat it at home. Close observation of your pets appetite will go a long way towards preventing this problem.
Symptoms include shaking, a starry eyed appearance, lethargy, shaking, greatly enlarged pupils, muscle tremors and even seizures. If the problem is serious and persists long enough, coma and even death can occur from depression of the respiratory system. Some pets don’t show any obvious symptoms except subtle behavior changes like sleeping more than usual. Since cats sleep most of the time anyway this can easily be missed.
In most cases the cause is an overdose of insulin. A common scenario involves a pet that eats significantly less than its normal amount for the day. Hypoglycemia can result if the dose of insulin is not adjusted to take this into account. If your pet is not eating well and you are unsure of its appetite, either give less insulin that day or do not give any at all. A blood glucose test in the hospital will let us know for sure.
Other causes of hypoglycemia include improper insulin administration resulting in an accidental overdose, along with cats that spontaneously recover from their diabetes and no longer need insulin. This is why close monitoring of the blood sugar level is important, either at home or at our office.
If the symptoms of hypoglycemia are mild, feed your pet some of its normal food. For many pets this will suffice. If the problem is severe use Karo syrup, a simple carbohydrate. It is readily available at the supermarket and should be kept on hand at all times. Give it in small amounts or rub it on the gums. Pancake syrup, honey, sugar water or any fluid that has high amounts of sugar can be used also. These high carbohydrate remedies only last a short time so you might have to keep on repeating one of them. Also, it is a good idea to have a source of simple carbohydrates in your car or other important locations when traveling or even just going for a walk. It pays to be prepared.
In the rare case that your pet has a seizure or seems comatose from hypoglycemia, it is imperative that you do not put anything into its mouth, including your fingers. These pets need to be seen by a veterinarian immediately.
Cats with diabetes are forced into using an energy source that will eventually cause a fatty infiltration of liver cells. As a result the liver will not function at optimum capacity, a potentially serious problem since the liver is such a vital organ. The liver enzyme test on the blood panel will alert us to this complication. When the diabetes is treated this problem might resolve. Radiography might reveal an enlarged liver (hepatomegaly) due to the fatty infiltration.
This liver is larger than normal-it is extending towards the right far beyond the margin of the ribs. The 4 white arrows on the bottom outline the lower edge of the wedge shaped and enlarged liver.
One of the most important disease syndromes associated with a fatty liver is called hepatic lipidosis. It occurs in overweight cats that are exposed to a stress that causes them to stop eating. This lack of appetite can become so severe that a feeding tube needs to be put in.
Keeping the blood glucose level as close to euglycemia as possible will help minimize this complication. Again, the need for periodic blood glucose monitoring along with a routine blood panel every 3-6 months become obvious.
Somogyi Effect (Insulin Induced Hyperglycemia)
Overdosing the morning dose of insulin can cause hypoglycemia. If the hypoglycemia becomes severe enough (< 60 mg/dl) the body will go through complex compensatory mechanisms to raise the blood glucose level. These mechanisms involve the liver, glucagon and epinephrine. If these mechanisms are unable to raise the blood glucose rapidly enough then the symptoms of hypoglycemia described above might occur.
When these mechanisms are able to correct the hypoglycemia they can cause the blood glucose level to go quite high later in the day and persist through the night. If the urine glucose is measured just before the morning dose the next day there will be significant glycosuria due to the previous afternoon and evenings hyperglycemia. This will cause many people to increase the insulin amount in the morning dose. This overdosing will again cause hypoglycemia some time during the day, and the cycle will repeat itself.
This problem is diagnosed by a blood glucose curve in the hospital. A cat with the Somogyi effect will have a blood glucose level that is abnormally low some time during the day. This emphasizes the need for a blood glucose curve to monitor your pet’s problem because only one blood glucose test during the day might miss the hypoglycemia episode that is causing this problem in the first place.
Pets that are not regulated in spite of higher than normal insulin doses might have this problem. This problem can mimic improper storage, handling, and administration of insulin.
There can be many causes to insulin antagonism. Hormones, cortisone, the Somogyi effect, adrenal gland disease, infection, chronic pancreatitis, kidney disease, cancer, anti-insulin antibodies, and even ineffective insulin all could be involved. Cats that get Feline Acromegaly, an excess of growth hormone, can also get insulin resistance.
Diabetic pets are prone to infections, especially of the urinary tract. These infections makes them more prone to DKA and insulin antagonism. Good dental hygiene is critical also since many pets with diabetes have dental disease. Chronic dental disease can make regulation almost impossible.
Almost all dogs with diabetes mellitus will eventually develop cataracts. The earlier the diagnosis is made the greater chance your dog’s blood glucose can be regulated to stave this off. One of our doctors might refer you to a veterinary ophthalmologist because there can be inflammation associated with this called uveitis. The cataract needs to be removed in this case to prevent pain and further complications. Your dog has to be properly regulated regarding insulin levels before the ophthalmologist can do this surgery.
It is always preferable to keep your diabetic pet in its normal environment. When this is not feasible special precautions need to be taken if your pet is boarded. Cats that board away from home are at an increased risk of becoming unregulated as to their correct insulin amount. They will frequently have a diminished appetite, increasing their chance of hypoglycemia if their insulin dose is not adjusted. Your cat should be boarded only at a facility that is adept at treating this disease and can run a blood glucose curve in case of a problem. One of the more common reasons we board pets at our hospital is because they need this type of medical monitoring for their problem.
A fructosamine test should be performed just prior to boarding for us to get an accurate idea of your pets average blood glucose level.
You should bring your food and your insulin to the boarding facility. A feeding schedule with amounts of food and water consumed and at what times should be provided. Also include a timetable when insulin is given and at what amount.
Since diabetic pets should be monitored with a blood glucose curve periodically this is an ideal time to run this test. Many cats will adapt to their new environment in a short time, which should make their individual blood glucose tests more reliable. When your return to pick up your pet we will review this curve with you and adjust doses as needed.
It is obvious that this is a complex disease that requires diligence on your part for proper control. Since every pet is different, your doctor will make a custom plan that will work for you and your pet, and will not necessarily follow any pre-established protocol. Be prepared for constantly changing insulin requirements and potential complications. The more consistent you are with feeding the same food, in the same amount, at the same time(s) every day, will add to a successful outcome.
The majority of diabetic pets on insulin therapy have a significantly increased quality of life. This usually makes the time time and monetary commitment necessary for proper regulation well worth the effort.