Insulin for Cats: A First-Choice Treatment for Diabetes

Cats can develop diabetes just as people do. Insulin is the gold standard approach to treating diabetes in cats.

Veterinarians have prescribed insulin injections to treat feline diabetes for decades. There’s often an adjustment period when a cat starts on insulin. But once things level off, a cat with diabetes can live happily on insulin for many years.

Here, we’ll discuss insulin as a diabetes treatment for cats.

What is insulin for cats, and how does it work?

Insulin is a hormone that regulates blood sugar. Cats normally produce their own insulin. But cats with diabetes need extra insulin to control their blood sugar.

There are different types of insulin available for cats. They include:

• Detemir (Levemir)

• Lente (Vetsulin)

• Protamine zinc insulin (PZI) (Prozinc)

• Glargine (Lantus, Basaglar)

Each of these insulin forms is slightly different. Each has advantages and disadvantages.

A veterinarian will choose an insulin for your cat based on several factors:

• Cost

• How long they maintain blood sugar levels

• Effectiveness

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Bear in mind that the best way to find the right insulin for your cat may be trial and error.

What is insulin used for in cats?

Insulin is used to treat feline diabetes. A cat with diabetes doesn’t produce enough insulin to control their blood sugar on their own. There are a couple of reasons why this may happen.

In some cats, the pancreas doesn’t make enough insulin. In other cases, a cat’s body makes enough insulin but doesn’t use it effectively. Regardless, cats with diabetes struggle to move sugar from the bloodstream into their body’s cells.

Untreated diabetes has many harmful effects, including:

• Weight loss

• Dehydration

• Vomiting

• Lethargy

• Weakness

Fortunately, insulin injections can regulate your cat’s blood sugar, preventing these harmful effects.

What is the dosage of insulin for cats, and how is it given?

A veterinarian will determine the best insulin type and dosage for your cat. A cat’s starting insulin dose is typically based on two factors:

• A cat’s body weight

• The type of insulin prescribed

Insulin shots are given twice a day under a cat’s skin. Cat owners give these injections to their cat at home. It can feel tricky at first, so make sure you ask your cat’s veterinary team to show you how to inject your cat. These steps may help:

1. Give your cat insulin with food. Eating causes an increase in your cat’s blood sugar. Insulin counteracts this increase.

2. Gently lift the skin on your cat’s torso, creating a tent.

3. Inject the insulin by holding the syringe parallel to your cat’s body.

4. Give the next shot in 12 hours. Remember to feed your cat at the same time.

Your veterinarian will monitor your cat’s response and adjust the dosage. It’s normal for a cat’s dosage to be adjusted several times.

Also, make sure your cat eats before taking insulin. If they don’t eat when it’s time to give insulin, your vet may recommend a different dosage.

Monitoring a cat on insulin

You will need to monitor your cat’s blood sugar levels regularly. Common forms of diabetes monitoring include:

• Blood glucose curve (blood tests done at home or in a veterinary hospital)

• Continuous glucose monitoring

• Fructosamine level (via blood testing)

Based on the results of monitoring, a veterinarian may increase or decrease your cat’s insulin dose. Dose adjustments are common in the first several months of therapy. Over time, however, you and a veterinarian will find the right dose, and your cat will likely remain on a steady insulin dose long term.

What are the most common side effects and serious risks of insulin for cats?

The most common side effect and serious risk associated with insulin for cats is hypoglycemia or low blood sugar. Insulin’s job is to lower blood sugar levels. But too much insulin can cause a dangerous dip in blood sugar.

Signs of hypoglycemia in cats include:

• Lethargy

• Weakness

• Vomiting

• Incoordination

• Seizures

• Loss of consciousness

Hypoglycemia is a medical emergency. If you see these signs, offer your cat food immediately. If your cat refuses to eat, give them sugar in the form of honey or corn syrup. If your cat won’t swallow these, try placing some on their gums. Then immediately take your cat to a veterinarian or an emergency veterinary hospital.

Do not put your hands in your cat’s mouth or force food or liquid if they are having a seizure.

In rare cases, cats may have an allergic reaction to insulin. Signs include:

• Hives

• Skin inflammation

• Shortness of breath

If your cat shows signs of an allergic reaction to insulin, contact a veterinarian right away.

Does insulin interact with any other cat medications?

Medications that may affect your cat’s insulin needs include:

• Heart medications such as ACE (angiotensin-converting enzyme) inhibitors and beta blockers

• Bronchodilators, such as albuterol and terbutaline

• Corticosteroids, such as prednisolone and dexamethasone

• Diuretics

• Fluoxetine (Prozac)

• Sedatives such as acepromazine and chlorpromazine

• Sulfonamide antibiotics such as sulfadimethoxine and sulfamethoxazole

These medications may increase or decrease your cat’s insulin requirements. Tell your veterinarian about any medications or supplements your cat takes before they prescribe insulin. This includes prescriptions, over-the-counter medications, and supplements.

What should you do if your cat misses a dose of insulin?

If you’re not sure if your cat received an insulin dose, do not repeat the injection. It’s safer for your cat to miss an insulin injection than to receive two injections too close to each other.

If you definitely missed giving your cat a dose of insulin, skip the missed dose and give your cat’s next insulin injection as scheduled. Insulin doses should always be given 12 hours apart and with food. It’s safest not to give a missed dose at a later time.

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Written by:

Catherine Barnette, DVM

Catherine Barnette, DVM, is a small animal veterinarian with 14 years of experience providing preventive care, medical workups, and surgical services in a number of general veterinary practices. She also served on her county's board of health for several years and taught biology laboratories for college students.

Edited by:

Renée Fabian, MA

Renée Fabian is the senior pet health editor at GoodRx. She’s worked for nearly 10 years as a journalist and editor across a wide range of health and well-being topics.

Reviewed by:

Ghanasyam Bey, DVM

Ghanasyam Bey, DVM, is from Cleveland, Ohio, and attended Princeton University for undergraduate studies. After a year of biology research at Duke University, he attended Ohio State College of Veterinary Medicine.

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