High Blood Sugar in Cats

What Is High Blood Sugar in Cats?

Like in people, cats’ blood sugar should stay in a specific range to maintain normal body processes. The normal range for a cat’s blood sugar, or blood glucose, is 80 to 120 mg/dL. However, certain situations can lead to high blood sugar, also called hyperglycemia, in cats.

The pancreas produces insulin, which is a hormone that helps blood glucose enter the body’s cells so it can be used as energy.

High blood glucose can develop if a cat’s pancreas does not produce enough insulin to regulate their blood sugar or if the insulin it produces does not effectively reduce blood glucose (i.e., insulin resistance). This condition is called diabetes mellitus. When blood glucose levels get too high, excess glucose will be eliminated in the cat’s urine.

High blood sugar on its own isn’t a medical emergency. However, unresolved feline hyperglycemia can quickly lead to diabetic ketoacidosis (DKA).

DKA develops when the liver breaks down fat because the body’s cells lack adequate glucose to use as an energy source. Fat breakdown produces chemicals called ketones, which can accumulate in the body and lead to serious, life-threatening illness.

Symptoms of High Blood Sugar in Cats

Symptoms of high blood sugar in cats include:

• Excessive water intake

• Excessive urination

• Increased appetite

• Weight loss

Cats who are seriously ill, such as those with diabetic ketoacidosis, usually have more severe clinical signs, including:

• Loss of appetite

• Vomiting

• Lethargy

Causes of High Blood Sugar in Cats

The leading cause of feline hyperglycemia is diabetes mellitus. One study estimated that approximately 1 in 200 cats has diabetes mellitus. Any cat can develop diabetes mellitus, but it’s most common in cats over 6 years of age.

Cats are usually overweight or obese when they develop diabetes, but then lose weight as the disease progresses. Tonkinese, Norwegian Forest Cats, and Burmese cats are reportedly predisposed to developing diabetes when compared to crossbred cats.

Additional causes of increased blood sugar in cats include:

• Anxiety—Stress, reactivity, or fear can increase blood sugar in cats. This commonly occurs during veterinary visits if cats become stressed out or irritable.

  • In this case, the blood sugar is only temporarily elevated and doesn’t reflect true disease.

• Cushing’s disease—Cushing’s disease, or hyperadrenocorticism, is an overproduction of cortisol due to a tumor of the pituitary gland or adrenal gland.

  • Cushing’s disease is associated with diabetes mellitus and is more common in dogs than cats.

• Acromegaly—Acromegaly occurs in cats who produce excess growth hormone, which is usually due to a tumor in the pituitary gland. This diagnosis should be considered in diabetic cats who continue to gain weight despite good control of the disease.

  • Acromegaly is most common in middle-aged to older male cats, and Maine Coon cats may be predisposed.

Other conditions that may predispose a cat to hyperglycemia include recurrent episodes of pancreatitis and kidney failure (especially acute or sudden failure).

Some medications, such as glucocorticoids (i.e., steroids, such as prednisolone), hormone drugs, and diuretics, increase the risk of hyperglycemia. In cats, this is most commonly associated with the long-term administration of steroids.

How Veterinarians Diagnose High Blood Sugar in Cats

Your veterinarian can detect high blood sugar with routine blood work during your cat’s annual wellness appointment.

High blood sugar can also be diagnosed using a drop of blood and a glucometer. If your veterinarian suspects diabetes, they may perform this test prior to running full blood work for a faster diagnosis.

Your vet may also perform urine testing, or urinalysis, to see if your cat has glucose in their urine.

To help your veterinarian make a diagnosis, important things to share about your cat include:

• Changes in appetite

• Changes in drinking or urinating habits

• Any vomiting

• Changes in weight

Treatment of High Blood Sugar in Cats

Diabetes mellitus is primarily managed with insulin administration and dietary changes. Your veterinarian can teach you how to give your cat insulin injections at home.

There are multiple types of insulin available, and your veterinarian will recommend the type that is best for your cat. Examples include:

• Protamine zinc insulin (ProZinc®)

• Glargine (Lantus®)

• Detemir (Levemir®)

For at-home administration of insulin, you will need insulin syringes and a safe way to dispose of needles. There are two types of insulin syringes: U-100 and U-40. You must ensure you use the right syringe type for the insulin’s concentration, or the dose you give will not be appropriate and could cause dangerously low blood sugar.

New oral treatments may be successful for some cats. For example, Bexacat™ (bexagliflozin tablets) is an insulin-free oral medication for diabetic cats that became available in 2023. This treatment is meant to help improve blood glucose levels in diabetic cats who haven’t been previously treated with insulin.

Your veterinarian may recommend a prescription diet to manage your cat’s diabetes. Some possibilities include:

• Purina® Pro Plan® Veterinary Diets DM Dietetic Management (dry or canned)

• Royal Canin®/MD Veterinary Diet Glycobalance (dry or canned)

• Hill’s Prescription Diet m/d GlucoSupport (dry or canned)

There are also over-the-counter options that may be appropriate for some cats. With strict dietary management, some cats can go into diabetic remission and will not be dependent on insulin.

There are also over-the-counter options that may be appropriate for some cats. With strict dietary management, some cats can go into diabetic remission and will not be dependent on insulin.

Transient feline hyperglycemia that occurs due to stress or anxiety doesn’t typically need to be treated with medication. However, your veterinarian may recommend ways to reduce stress for future veterinary visits. These may include anti-anxiety medications, like gabapentin, or feline pheromone products.

Recovery and Management of High Blood Sugar in Cats

Some cats can go into diabetic remission. According to the American Animal Hospital Association (AAHA), your cat has the best chance of going into remission if you achieve good blood glucose control within six months of diagnosis. Cats who do not achieve diabetic remission will be dependent on medical treatment for the remainder of their life.

Because diabetes causes your cat to urinate more, it’s important that your cat always has access to fresh water and a clean litter box. Cats with diabetes are also more likely to develop urinary tract infections, so contact your veterinarian if you notice your cat straining in the litter box or frequently urinating small amounts, or if you see blood in your cat’s urine.

Control of diabetes requires strict dietary management. This includes providing a well-balanced diet and usual feeding routine, restricting your cat’s access to treats, and not feeding table scraps.

Prevention of High Blood Sugar in Cats

To help prevent your cat from developing diabetes, keep them at a healthy weight and feed them a healthy diet. Schedule annual wellness exams, including blood work, with your veterinarian, who will assess your cat’s weight and make any recommendations about dietary changes.