Diabetes in Cats: Symptoms, Causes, Risk Factors, Treatment, and Life Expectancy

PetMD Editorial
April 27, 2020
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Diabetes mellitus (commonly referred to as diabetes) is a disease of the endocrine system that results from an insulin deficiency. Either the body doesn’t produce enough insulin, or it can’t use the insulin that’s produced.

You may be surprised to find out that cats can have diabetes, too. Here’s a complete guide to diabetes in cats, from symptoms and causes to treatment and life expectancy.

Why Is Insulin So Important?

Insulin is a hormone produced by the beta cells of the pancreas, a small but vital organ located next to the upper segment of the small intestine.

Insulin is necessary for regulating the level of glucose (sugar) in the bloodstream and controlling the delivery of glucose to tissues in a cat’s body. When insulin is present and functioning normally, glucose is transported from the blood into the tissues and converted by the cells into energy.

In cats with diabetes mellitus, the transport of glucose from the blood to the tissues is disrupted, resulting in hyperglycemia (elevated blood glucose) and a state of relative starvation.

Types of Diabetes in Cats

Similar to people, several classifications of diabetes mellitus exist in veterinary medicine.

Type I Diabetes Mellitus

Type I diabetes mellitus is also called insulin-deficient diabetes. This type of diabetes, where the pancreas is unable to produce the level of insulin that the body needs, is rarely seen in cats.

Type II Diabetes Mellitus

Type II diabetes mellitus is also called insulin-resistant or non-insulin-dependent diabetes. This is the most common form of diabetes mellitus in cats.

Type II diabetes is characterized by a relative insulin deficiency. This means that even though the cat’s pancreas may produce adequate levels of insulin, the tissues are unable to use it for glucose metabolism.

Which Cats Are at Risk for Diabetes?

It is estimated that between 0.5-1% of the general feline population suffers from diabetes, but an increasing number of cats are being diagnosed each year.

Any cat has the potential to develop diabetes throughout their lifetime, but certain breeds, such as the Burmese, have been reported to carry a higher lifetime risk.

Most commonly, diabetes is seen in middle-aged, male indoor cats that are obese.

The most important risk factors for diabetes mellitus in cats are:

  • Obesity

  • Lack of physical activity

  • Increasing age

  • Gender (males are diagnosed more frequently than females)

  • Castration (being neutered)

  • Glucocorticoid (steroid) therapy

Certain medical conditions may also predispose a cat to developing diabetes.

Most Common Signs of Diabetes Mellitus in Cats 

If left untreated, diabetes mellitus can progress to a stage of the disease that is life-threatening for cats. So it’s important for you to know the symptoms of diabetes in cats, and to contact your veterinarian right away if you believe that your cat may be experiencing any of them.

  • Increased thirst

  • Increase in frequency and volume of urination

  • Urinating outside the litter box

  • Increased appetite

  • Weight loss (despite a hearty appetite)

  • Vomiting

  • Muscle wasting

  • Lethargy or weakness

  • Poor coat quality (oily coat, dandruff)

  • Plantigrade stance (less common)

In cases of uncontrolled diabetes, cats may develop damage to the nerves in their hind limbs, which causes a plantigrade stance. Instead of walking on their paws, these cats walk with a “dropped hock,” where their whole foot almost or completely touching the ground. This is a form of diabetic neuropathy.

Unfortunately, many of the symptoms of diabetes in cats are not specific to diabetes alone. So take your cat to your veterinarian to rule out other diseases (such as kidney disease, hyperthyroidism, acromegaly, or pancreatitis).

How Blood Glucose Relates to the Symptoms You See

In all cases of diabetes mellitus (regardless of type), there is an excessive level of glucose in the blood (hyperglycemia).

When the blood glucose reaches a certain threshold, it begins to overflow into the urine (glucosuria) and draws large volumes of water out with it. This results in excessive urination (polyuria) and dehydration.

In an effort to combat dehydration, cats often also begin drinking excessive amounts of water (polydipsia). 

Despite the elevated level of glucose in the blood, not enough glucose is transported to the cells, so they become starved for energy.

In response to perceived starvation, a cat’s body begins to break down fat and protein stores for energy, which results in weight loss and cachexia (muscle wasting) in cats. This weight loss often occurs despite the cat having an increased appetite (polyphagia).

How Do Vets Diagnose Feline Diabetes?

Diabetes is diagnosed by the presence of the typical clinical signs in the face of persistent fasting hyperglycemia (elevated blood glucose), and glucosuria (glucose in the urine).

This can be diagnosed by performing full bloodwork and a urinalysis. Your veterinarian may also use the blood sample to perform a serum fructosamine, which allows them to prove that the blood glucose has been elevated over time, and not just at the time it was measured in the hospital.

Diabetic Ketoacidosis

Through additional testing, your veterinarian might also find:

  • Elevated liver enzymes

  • Elevated kidney values

  • The presence of ketones in the blood or urine

  • Electrolyte imbalances

  • Other metabolic disturbances

These symptoms may be caused by diabetic ketoacidosis (DKA).

DKA is a form of diabetes in which the cells (which cannot access glucose) use free fatty acids as an energy source. These free fatty acids are broken down into molecules called ketoacids.

As ketoacids and glucose accumulate in the blood, it can become life-threatening for your cat.

Cats that have progressed to a state of DKA have more severe clinical signs, which may include:

  • Vomiting

  • Anorexia (not eating)

  • Diarrhea

  • Progressive weakness or lethargy

  • Depression

  • Coma

In these cases, your cat needs a full workup, including x-rays and an ultrasound, which will help identify other diseases and diabetic complications.

Treatment of Feline Diabetes

Managing feline diabetes is a lifelong commitment that requires vigilance and good communication between you and your veterinarian.

At the time of diagnosis, your cat may need to be hospitalized for several days until their glucose level is controlled and they are feeling well. If your cat is in a state of diabetic ketoacidosis at the time of diagnosis, they will likely require extended hospital stays and intensive care.

The primary goals of treatment of feline diabetes are centered on:

  • Restoring normal blood-glucose levels

  • Reducing or eliminating the clinical signs of excess thirst and urination

  • Normalizing weight and appetite

  • Avoiding inducing inappropriately low glucose levels

Your veterinarian will develop a plan that is tailored to your cat’s specific needs. If your cat has concurrent diseases, your veterinarian will recommend treatment for those as well.

At-Home Insulin Therapy

The vast majority of cats diagnosed with diabetes mellitus require daily injectable insulin therapy.

Oral diabetic drugs, such as those used in human patients, are typically less effective and prescribed much less frequently for cats.

Blood-Glucose Curve

There are a variety of different insulin preparations available for cats, and each cat responds to insulin therapy differently (some are more sensitive than others).

As such, performing a blood-glucose curve at the time of diagnosis is very important. This is a series of timed blood-glucose measurements taken over the course of a day, most often in the hospital.

A blood-glucose curve will identify the insulin type and dosing frequency that works best to control your cat’s glucose levels, while avoiding periods of inappropriately low glucose (hypoglycemia).

Once an effective treatment plan has been identified, your veterinarian will show you the proper way to administer insulin injections at home. Follow your veterinarian’s instructions closely.

Adjusting Your Cat’s Insulin Dose

Unfortunately, regulating feline diabetes can be complicated, and it’s normal for the vet to make frequent changes to your cat’s treatment plan, especially at the time of diagnosis.

After your cat has been receiving insulin at home for a week or so, they will need to return to the veterinarian to have a glucose curve performed.

Based on your cat’s symptoms and the test results, the insulin dose is adjusted, and the glucose curve is repeated. This cycle continues until your cat has fewer or lessened symptoms and their blood-glucose levels are controlled within an acceptable range.

It may take up to several months to find the right insulin dose to regulate your cat’s diabetes.

Caring for a Diabetic Cat

You will need to do a few tasks consistently to help manage your cat’s diabetes.

Monitoring Your Cat’s Glucose Levels

At-home monitoring of your cat’s blood-glucose levels is important for monitoring your cat’s glycemic control long-term. This typically involves pricking the inside of your cat’s ear and using a glucometer (alpha-trak).

Glucose levels can also be monitored in a less invasive manner, by measuring glucose levels in the urine, although this method is not as accurate as blood measurements.

Not all cats are amenable to blood-glucose monitoring at home. Your veterinarian will work with you to determine the method of monitoring that works best for you and your cat.

Monitoring Your Cat’s Insulin Response

One of the most serious risks and potential complication of managing a diabetic cat at home is the risk of hypoglycemia (low blood sugar).

This can happen to any pet being managed for diabetes at home, even if you give them the appropriate dose (or less than the appropriate dose) prescribed by the veterinarian.

For this reason, it’s important that you strictly follow your veterinarian’s instructions and schedule for feeding and giving insulin, and that you never administer a full dose of insulin to your pet if they are not eating.

Signs of Hypoglycemia in Cats

Hypoglycemia is a serious and potentially life-threatening state that should be treated as an emergency.

Signs of hypoglycemia in cats might include:

  • Dull mentation or disorientation

  • Profound weakness or lethargy

  • Gastrointestinal signs (vomiting, diarrhea, not eating)

  • Trembling

  • Seizures

  • Coma

If you see any of these signs, give your cat a sugary product (corn syrup, maple syrup, honey) and immediately go to an emergency pet hospital.

If your pet is having seizures, try rubbing syrup on their gums, but be cautious of your cat biting you.

Managing Your Cat’s Diet and Weight

Nutrition is a very important part of managing diabetes in cats.

Your veterinarian may recommend a diet change to help regulate your cat’s glucose levels and promote weight loss, as obesity complicates diabetes management.

This often involves switching your cat to a high-protein, low-carbohydrate diet. There are several diabetic prescription diets on the market for cats, and your veterinarian will work with you to identify a diet plan that is appropriate for your cat.

Once you have identified a nutritional plan that works for your cat, it’s critical that you maintain a strict feeding schedule.

Do NOT change your cat’s diet suddenly without consulting your veterinarian.

Providing Appropriate Exercise

Keeping your cat physically active is another important component of helping your cat achieve a healthy weight. Ask your veterinarian for tips on how you can encourage your cat to be more active.

If taken seriously, and appropriate weight loss is achieved, diabetic cats may even enter diabetic remission, a point where at-home insulin injections are no longer necessary.

Keeping a Daily Log of Your Cat’s Health

You need to keep a daily log of your cat's diet, glucose test results, daily insulin dose, and weekly body weight so you can see trends and recognize when your cat deviates from their regular pattern. Any change in patterns should be brought to your vet’s attention.  

Life Expectancy for Diabetic Cats

Treatment of feline diabetes is a major, life-long commitment requiring significant dedication from all family members. It also requires consistent, open communication with your cat’s veterinarian.

With appropriate veterinary care and at-home management, cats diagnosed with diabetes mellitus can go on to live a healthy and happy life without having their diabetes shorten their life expectancy considerably. In some cases, diabetic cats may even go into remission.

If your cat was diagnosed with other illnesses, this might complicate the regulation of your cat’s diabetes and/or affect your cat’s long-term prognosis.

Featured Image: iStock.com/borchee