Pet Connections

How Sweet It Isn’t – Diabetes in Cats and Dogs

As you probably already know, diabetes has something to do with blood glucose (a sugar) and insulin. After we eat and food is digested, the glucose and other nutrients enter the bloodstream to be delivered to our cells. Cells need energy to survive and perform their various functions. These nutrients also provide building blocks for the manufacture of proteins, lipids, and carbohydrates that the body needs. The major source of energy for cells is glucose, but it is too big to enter cells without help from glucose transporters. Here’s where insulin comes in. Insulin binds to a receptor on the cell membrane, triggering the glucose transporters to move into place. So, for everything to work properly, we need insulin along with enough functional receptors that trigger enough glucose transport proteins to be placed in the cell membrane.

When things go wrong with any of these, diabetes mellitus results. Type I diabetes is caused by a lack of insulin being secreted by the pancreas. Like in people with type I diabetes, it is probably caused by the immune system attacking the cells that make the insulin. Dogs get this type. Type II diabetes results from a decreased response to insulin, usually due to fewer insulin receptors. The vast majority of diabetic cats have this type. Regardless of the type, diabetes prevents the glucose from being used as energy, leaving the cells to find alternative sources. These sources are fats and proteins.

Fats and proteins can be used in the short term, but the buildup of acidic compounds, called ketone bodies, occurs over time. If diabetes remains undiagnosed and untreated, diabetic ketoacidosis (DKA) can result. Dogs and cats in DKA present with lethargy, anorexia, vomiting, weakness, and gait abnormalities due to the acid buildup and associated electrolyte imbalances. Although all the body’s cells suffer from these changes, the most concerning is when muscle cells in the heart or blood vessels do not perform properly. If blood pressure drops too low, oxygen cannot be delivered, and all the organs will fail.

The good news is that proper diagnosis and treatment of diabetes can prevent DKA. If you have a pet who is eating, drinking, and urinating more as well as losing weight, diabetes should be a concern. Because diabetes prevents cells from using glucose, this important energy source goes out with the urine. Consequently, animals with diabetes will lose weight and have a ravenous appetite. Diabetics also urinate large volumes because the glucose in the urine takes water out with it. Loss of too much water causes more thirst and, hence, increased drinking. Nerves may also be affected, and some diabetic cats walk “flatfooted” due to neuropathy.

Bloodwork and a urinalysis will be necessary to make the diagnosis of diabetes. As expected, we are looking for a high blood glucose as well as glucose in the urine. Sometime blood fructosamine is measured to assess the average blood glucose levels from the past week or so. Once we know a pet is diabetic, treatment and follow-up monitoring can begin. Most diabetic animals will be treated with insulin injections. Diet changes are often recommended as well. This is especially important with cats, since a lower carbohydrate diet (often an all-canned food diet), can make a difference in their response to therapy. Cats can even go into remission for periods of time and not need insulin. This is why monitoring is so important. 

Monitoring a diabetic pet’s appetite, approximate water consumption/urine output, and weight are all very important. Weight stabilizes and eating, drinking, and urine output all decrease as diabetes becomes controlled. Periodic blood glucose levels are also important to monitor, but we have to remember that stress will falsely elevate our results, especially in cats. We get around this by having the pet parent monitor the blood glucose at home by pricking the tip of the ear (like a human pricks a finger). If we need frequent readings on diabetic cats, we apply a device that monitors the glucose with the use of a cell phone, just like in people! This greatly reduces the stress and gives us good data, so we know how to adjust the insulin amounts.

I have had many feline patients on insulin for many years. For both dogs and cats, our goal is to keep the clinical signs of diabetes controlled while being careful to prevent hypoglycemia. Even if giving injections seems scary, I have always been successful in teaching people how to administer them. Even my mother who never even picked up a cat before I started taking in strays, became an expert insulin injector. Just putting down a plate of yummy, canned food was typically enough of a distractor, and Tiger didn’t even know he got a shot. So don’t fret if you find out your furry family member has diabetes. A little insulin and some tasty food go a long way.


December 14, 2023
December 14, 2023