If your cat has been diagnosed with diabetes, your veterinarian has likely prescribed insulin to help manage this condition. You may have heard of insulin being used to manage human diabetes, but how does it work in cats? Let’s take a look at this essential hormone and its use in our diabetic felines.

What Is Insulin?

Insulin is a hormone naturally produced by the pancreas. It is responsible for controlling the amount of glucose, or sugar, in your cat’s bloodstream and promoting the uptake of glucose into cells. 

After your cat eats a meal, insulin is released from the pancreas to help the body use or store the glucose it gets from food. In cats with diabetes, the pancreas may still produce insulin but the body does not respond to it appropriately (insulin resistance), causing poor regulation of blood glucose levels. This is most similar to Type II diabetes in humans.

To treat diabetes in cats, we must supplement them with insulin by injection. There are multiple types of insulin for cats available that vary in their duration of action, concentration, and cost. 

What Does Insulin for Cats Look Like?

There are many insulin products available and they come in several forms. Most commonly, insulin comes in a multi-dose vial. Human insulin products may be sold in a dosing pen for more accurate dosing. Your veterinarian will demonstrate how to use the product prior to starting your cat’s insulin therapy.

How Does Insulin Work?

Insulin is a hormone that primarily targets liver, muscle, and fat cells. In a diabetic cat, insulin is administered after a meal. As the body breaks down the food into glucose, insulin signals these cells to uptake glucose into the cell, where it is either used as fuel for energy or stored for later use. This uptake of glucose into cells keeps your cat’s blood sugar regulated so that it does not become too high (hyperglycemia). 

What Is Insulin Used for In Cats?

Insulin is used to treat diabetes mellitus, a common condition in senior cats, particularly males. Risk factors for diabetes mellitus include obesity, physical inactivity, increasing age, history of glucocorticoid administration, pancreatitis, pregnancy, systemic infection, acromegaly, hyperadrenocorticism, and chronic kidney disease.

Cat Insulin vs. Human Insulin

There are only two insulin products that are FDA approved for use in cats. These are Vetsulin, a porcine insulin zinc suspension, and ProZinc, a protamine zinc recombinant human insulin. 

Aside from these two products, many human products are also used in cats. These include products such as Lantus, Toujeo, Humulin N, and Novolin N which are commonly used in human medicine. 

There is no single insulin that is suitable for all diabetic cats. Some cats may respond better to one insulin product than another. Your veterinarian will choose an insulin product based on its duration of action, your cat’s response to insulin therapy, and their own clinical experience with insulin products. 

How to Give Insulin to Cats

Insulin is administered by subcutaneous injection, which is an injection under the skin. Insulin syringes use a small, thin needle and most cats tolerate these injections very well. Your cat will need to have these injections 1-2 times daily for the rest of his or her life.

To administer the injection, start by giving your cat a small treat or a bit of food as a distraction. Use your non-dominant hand to gently lift a bit of loose skin from the nape of the neck. You’ll notice that this skin forms a triangle shape. Using your dominant hand, guide the needle into the center of the triangle. When the needle is in place, pull back slightly on the syringe plunger. You should experience a bit of negative pressure or a slight “pull” on the plunger – this means you are in the right position. Gently depress the plunger until you have fully administered the insulin, then gently pull back the syringe to remove the needle. Dispose of the entire syringe and needle in an appropriate hard-sided container. 

If you’re unsure if your cat received the entire contents of the syringe, do not attempt to re-dose your cat. You do not want to accidentally overdose your cat with insulin as this can lead to hypoglycemia, or dangerously low blood sugar. Instead, simply continue on with the regular dosing schedule as prescribed.

Side Effects of Insulin for Cats

The primary side effect of insulin is hypoglycemia, or low blood sugar. This can occur when an insulin dose is too high, resulting in too much glucose uptake from the bloodstream. Signs of low blood sugar in cats include:

• Hunger
• Anxiety
• Weakness
• Muscle twitching
• Disorientation
• Lethargy
• Loss of appetite
• Vomiting
• Hypothermia
• Seizure
• Diarrhea

Other side effects from insulin include local injection site reactions such as mild swelling, pain, bruising, or crusting at the site of insulin injection. It is recommended to rotate injection sites to help prevent this.

Reactions With Other Drugs and Medications

Certain drugs may alter an animal’s glucose tolerance and change their insulin requirements. These drugs include:

• Corticosteroids
• Thiazide diuretics
• Progestogens
• Amitraz
• Alpha-2 agonists
• Dexmedetomidine
• Xylazine

Certain drugs may increase the risk of hypoglycemia (low blood sugar) when given in conjunction with insulin. These drugs include:

• Anti-diabetic agents
• Salicylates
• Sulfonamide antibiotics
• MAOIs
• Fluoxetine
• Disopyramide
• Dibrates
• Propoxyphene
• Pentoxyfylline
• ACE inhibitors
• Angiotensin II receptor blocking agents
• Somatostatin analogs

Insulin Dosage for Cats

The dosage of insulin your cat needs will vary depending on your cat. Some cats require higher doses of insulin than others, and it can take some time to find the right dose. Your veterinarian will start by prescribing a low dose of insulin for your cat. After your cat has been on insulin for about 7-14 days, the dose may be adjusted based on your cat’s clinical signs or based on the results of a blood glucose curve. 

A blood glucose curve is a diagnostic procedure in which your cat’s blood sugar is measured every 2 hours, allowing your veterinarian to chart how your cat’s blood sugar fluctuates throughout the day. This allows your veterinarian to visualize how your cat’s body is reacting to the insulin. If your cat’s blood sugar is trending high, your cat’s insulin dose may be increased. If your cat’s blood sugar is dipping too low during the day, your cat’s insulin dose may be decreased. 

When starting insulin therapy, it is important to monitor your cat for signs of hypoglycemia, or low blood sugar. These signs can include weakness, loss of appetite, stumbling, blindness, altered mental state, vomiting, panting, slow heart rate, and collapse. These can be signs that your cat’s insulin dose is too high. If your cat exhibits these signs, contact your veterinarian right away. 

What If My Cat Misses a Dose of Insulin?

If your cat misses a dose of insulin, do not double the next dose or give an extra dose to make up for the missed dose. Doing so will put your cat at risk for hypoglycemia. Instead, simply skip the missed dose and continue on with the next dose as prescribed. If your cat misses multiple doses of insulin, contact your veterinarian for advice on how best to proceed.

Cost of Insulin for Cats

The cost of insulin for cats varies depending on the type of insulin your cat is prescribed. However, pet owners should expect to spend approximately $100-$150 per bottle of insulin. 

Insulin Storage Instructions

Insulin products are stored in the refrigerator at 36 to 46 degrees Fahrenheit and should be kept away from heat and sunlight. Do not freeze insulin or use insulin that has been frozen.