Diabetes in Cats
- Mary Malucci
- Jan 23, 2025
- 7 min read
Updated: Jan 23, 2025
The pancreas is a multi-talented organ with a lot of responsibility. To discuss diabetes, we will focus on pancreatic beta cells, which produce insulin. Insulin regulates the level of glucose (sugar) in the bloodstream and controls the delivery of glucose to the tissues of the body.
Diabetes mellitus is the second most common endocrine disease in cats. An estimated 1 in 100 cats will develop diabetes, especially middle-aged or senior cats. It’s more common in males than in females and in cats that are overweight or obese. Obesity in cats is defined as weighing three pounds over the cat’s ideal weight. This means the average domestic cat weighing 13 pounds or more is at high risk of developing type II diabetes mellitus. Certain medications, like steroids, can also contribute to the development of diabetes.
Types of Diabetes in Cats
Type I— Called insulin-deficient diabetes, Type I diabetes results from total or near-complete destruction of the beta cells, leaving the pancreas unable to produce insulin. This form is rarely seen in cats.
Type II—Type II diabetes mellitus is also called insulin-resistant or non-insulin-dependent diabetes. Some insulin-producing cells remain, but their insulin production is insufficient, or the insulin secreting response is delayed, or the cat's body tissues are relatively insulin resistant. This is the most common form of diabetes mellitus in cats, constituting 85-95% of feline cases.
Type III diabetes results from insulin resistance caused by other hormones and can be due to pregnancy or hormone-secreting tumors.
Unregulated or undiagnosed diabetes can lead to a life-threatening condition called diabetic ketoacidosis or DKA. DKA is a medical emergency that occurs when there is not enough insulin in the body to control blood sugar (glucose) levels or the body cannot use the insulin effectively, causing blood glucose levels to rise 2-3 times more than normal. As the cat’s body gets more desperate for fuel, it will start burning fat instead, creating ketones. As ketone levels rise, they affect the body’s pH balance, causing it to become more acidic. When the body becomes more acidic (acidosis), it can't maintain an appropriate fluid balance. The electrolyte balance becomes disrupted, which can lead to abnormal heart rhythms and abnormal muscle function. DKA can develop because there is another disease going on in the cat, such as a urinary or kidney infection, pancreatitis, liver disease or intestinal disease, so your veterinarian may want to test for these also. If left untreated, diabetic ketoacidosis is fatal.
Often the first signs a pet parent notices are increased thirst and increased urination. Called polydipsia (PD), signs of increased thirst can be as subtle as refilling the water bowl more often. One sign of increased urination, called polyuria (PU), is scooping more urine out of the litter pan. Another sign is a cat who starts urinating outside the litter pan when it hasn’t done that before. Both of these signs are related to the very high levels of glucose circulating in the blood. In the early stages of diabetes, a pet’s appetite often increases but the cat is losing weight despite eating well.
As the disease progresses, that healthy seeming appetite may start to decrease, and the cat may start vomiting. Weight loss will continue, and muscle wasting will become more evident. The cat becomes lethargic and uncharacteristically irritable. They may lose interest in grooming, allowing their coat to become unkempt. They may also develop weakness.
Sometimes, uncontrolled diabetes in cats may cause damage to the nerves in their hind limbs. Instead of walking on their paw pads, these cats walk with their hocks closer to or touching the ground, using their whole foot instead. Called a plantigrade stance or a dropped hock, this is always an abnormal gait.
In addition to these symptoms, if a cat’s diabetes progresses to DKA status, you may also see significant dehydration and an increased respiratory rate.
A diagnosis of diabetes will be based on three things. Your veterinarian will listen for typical clinical signs in your cat’s history, like PU/PD. Blood work will be done to measure the blood glucose and screen for other diseases. Medical conditions like hyperthyroidism, pancreatitis and asthma may put a cat more at risk for developing diabetes. Electrolyte imbalances may suggest the pet is in DKA. An elevated blood glucose by itself is not diagnostic for diabetes in cats because their blood glucose will spike in response to stress. Another blood test called a serum fructosamine helps measure the average blood glucose levels over the past 7-14 days. An elevated fructosamine confirms the diagnosis of diabetes.
A urinalysis will also be run to look for glucose in the urine. Normally, your cat’s kidneys do not filter glucose out of the blood and into the urine until an excessively high level has been reached. Healthy cats typically have no glucose in their urine, whereas unregulated diabetic cats always do. Cats who have progressed to DKA status often have ketones in their urine also.
Unfortunately, there is no cure for diabetes in cats. Newly diagnosed diabetic cats may need to be hospitalized to initiate treatment, especially if there are concurrent diseases. Symptomatic cats diagnosed with DKA need to be hospitalized, often for several days, on intravenous fluid therapy to address dehydration and electrolyte imbalances, like low potassium levels. While hospitalized, your veterinarian will monitor blood glucose levels and start insulin administration to regulate the blood glucose. Your cat’s acid/base balance will also be monitored. Your cat will be released from the hospital when all these parameters are close to or within normal limits.
Managing a newly diagnosed diabetic cat is often intimidating to owners. Diabetes is a chronic condition, and these cats need to be monitored and treated for the rest of their lives. Until very recently, insulin injections were the only form of treatment available. In the last few years, oral medications have been released that lower the blood glucose by pushing the excess glucose into the urine. We’ll talk more about these oral medications later.
There are several different types of insulin available, and your veterinarian will help you choose the most appropriate one for your cat. Insulin syringes must be used to measure the insulin accurately. All insulin syringes have tiny needles that most cats tolerate well. Many cats need insulin injections once or twice a day. Finding the right insulin dose for your cat may require several vet visits and may take several days or weeks.
If you and your veterinarian decide to use one of the new oral medications to manage your cat’s diabetes, be aware that these meds make it more difficult to diagnose possible DKA. They force glucose out of the blood and into the urine, thus lowering the circulating blood glucose levels. The idea is to rest the beta cells so they start producing insulin again. This may be enough for most cats. However, some cats will still develop DKA despite this medication because their tissues are insulin resistant. To diagnose DKA in cats taking these oral meds, your veterinarian will have to test for ketones in blood and urine. These cats will need to be transitioned over to insulin for future management.
Monitoring your cat’s blood glucose levels at home can be done with a glucometer, like AlphaTrak, or with a continuous glucose monitoring system like the Freestyle Libre.
Using a glucometer requires obtaining a drop of blood, usually by pricking the ear pinna. The glucometer will give you an answer within a minute and the results are sensitive enough to track trends. The obvious drawback is that some cats are not going to tolerate having their ear pinnas pricked.
Continuous glucose monitoring systems need time after application to calibrate, usually 12 hours, before the readings are considered accurate. However, these provide a non-invasive way to measure the blood glucose as often as the owner needs to do so. The drawback here is these monitors don’t work well on very thin cats or obese cats.
Before the availability of AlphaTraks and Freestyle Libres, the only way to monitor glucose at home was to measure it in the urine with a urine test strip. This approach is less sensitive than measuring blood glucose and should be considered a screen to indicate a need for more accurate testing. Never adjust insulin doses based on urine glucose measurements.
All of these measurements can be entered into the Daily Log you will start keeping on your diabetic cat. Each day’s entry should include the following: time and amount of insulin injected; time, amount and type of food offered and eaten; glucose test results and amount of water drank. Once a week, weigh your cat and record it also. Include notes about what may be important to discuss with your veterinarian at your next visit.
Nutrition plays an important role in managing diabetic cats. There are prescription diets available to help regulate blood glucose and reduce weight. Your veterinarian will help you choose the best one for your cat. Once you find the diet that works for both you and your cat, try to maintain a strict feeding routine so you can maintain a consistent insulin schedule.
If your cat refuses to eat a meal, do not give him insulin! If a cat who isn’t eating receives insulin, it may cause the blood glucose to drop dangerously low. Low blood sugar is a medical emergency! A cat with very low blood sugar will show signs like weakness, lethargy, and tremors. These cats look wobbly when trying to walk or seem less responsive than usual. If the sugar drops low enough, the cat may start convulsing. Check your cat’s blood glucose, if possible, and seek veterinary care immediately.
Cats diagnosed with diabetes in the earlier stages can live long healthy lives if treated properly. Cats who develop DKA or have other diseases happening in addition to diabetes can be more difficult to regulate and generally have a poorer prognosis.
Diabetes in Cats: Signs, Treatment, and Prognosis
Diabetes Mellitus in Cats: Overview
Diabetic Ketoacidosis in Cats
Feline Diabetes
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