Diabetes in Cats

cat with vet

When my family and I lived in North Carolina, we had minivacations on the Outer Banks. One night, as we were leaving a restaurant, we saw a little kitten trying to hide under a bush. Of course, we coaxed him out. He was a stray with fleas, ear mites, and a round little belly. He got his first bath in a hotel bathtub and rode the three hours home with nary a peep. We named him Flip because we found him under a restaurant called Flipperz. A week later a hurricane hit that area of the Outer Banks, but that’s another story.

Flip was a pretty good cat and maintained his rotund shape no matter what he was fed. He was a small, fluffy basketball! When he was about eight years old, we moved to Madison. He and our other cats adjusted to the new home and all seemed well. We were then happy to discover that Flip was losing weight. We assumed more exercise in a bigger house and the weight loss diet were finally working. He went from chubby to normal to skinny before I started thinking the weight loss wasn’t appropriate. He was hungry all the time and eating at least as much as the other cats.

While I hate to admit this to a large audience, I’m not a good litter box cleaner. We have two very large litter boxes and scoop only twice a week. Thus, there’s always a lot of urine in each box. I started to notice that the litter clumps had become much bigger, and there were more concretions of litter rather than clumps. What was going on?

Cats are masters at hiding illness. They sleep a lot, so it can be difficult to tell if they’re lethargic, running a fever, or in pain. And if food is left out all the time, it takes a while to notice if one cat in a household isn’t eating much. Until their collar falls off because it’s loose, weight loss can be missed.

It eventually dawned on me that something was going on with Flip. He was always the first one to his food bowl, and we were giving him between-meal snacks because he was begging so much. I noticed him at the water bowl more frequently than the other cats. He hung around on the main floor rather than going upstairs to sleep. His normal routines were just off. Into the cat carrier he went to spend a day at the office with mom.

When weighing Flip, I found he had lost about three pounds. Since I hadn’t changed his diet and he wasn’t exercising much, it was definitely significant. Blood was drawn, urine and feces obtained, and all sent off to the lab. There were a number of things that could be causing Flip’s symptoms.

Unexpected Weight Loss

Veterinarians consider several causes, including diet change, an overactive thyroid gland, kidney failure, lymphoma (or other cancer), chronic pancreatitis, diabetes mellitus, intestinal parasites, and inflammatory bowel disease.

Increased Drinking and Urination

We think about a urinary tract infection, crystals in the urine, increased drinking due to a salty diet, fever, overheating, diabetes, and kidney disease.

Increased Appetite

Could be from an overactive thyroid gland, the pancreas not producing digestive enzymes, a more palatable diet, intestinal parasites, or diabetes.

It was important to get all the samples to get a complete picture of what was going on internally in Flip. When the results returned, the diagnosis was diabetes mellitus. As most people know, diabetes occurs when the body cannot use glucose (the main source of energy for the cells in the body) normally. Glucose levels in the blood are primarily controlled by insulin, which is made by the pancreas. Normally, as food passes through the intestines during digestion, glucose is absorbed into the blood and delivered to all the cells in the body. Insulin is needed for the glucose to get out of the blood and into the cells. When there isn’t enough insulin, glucose builds up in the blood stream—this is called hyperglycemia. When the blood glucose reaches a certain level, the sugar overflows into the urine, taking lots of water with it. Thus, diabetic pets drink a lot of water and urinate large amounts frequently.

Since the glucose can’t get into the cells without insulin, the cells don’t function normally, and the tissues starve. This leads to the body breaking down fat and muscle, which is converted in the liver to sugar. This breakdown of fat and muscle leads to weight loss.

Unfortunately, insulin injections are the only way to treat pets for diabetes. I started Flip on twice-a-day insulin injections, which didn’t bother him at all. Diabetes in cats is often due to obesity and a high carbohydrate diet, which can cause insulin resistance—the cells in the body don’t respond to insulin like they should. I also fed Flip a canned food diet that was very low in carbohydrates and high in protein.

Flip responded very well to treatment, and his glucose level stabilized. He stopped being so ravenous, put on weight, and the litter box output went back to normal. Then, a couple months later, he seemed lethargic again—he just wasn’t active. I checked his glucose level and found it very low. Because of the change in diet and getting the diabetes under control with insulin, he went into diabetic remission. His body was producing and responding to his insulin again. I stopped the insulin injections and kept him on the diet, and he stayed in remission for about six months. Just long enough for me to decide I could throw away that expensive vial of insulin in the refrigerator.

I knew he was no longer in remission because he started having the same signs of diabetes. We restarted his insulin injections, and he stayed diabetic the rest of his life.

Diabetes is treatable but can be expensive and requires injections about every 12 hours. It’s estimated that about 1 percent of cats are diabetic, but I think the percentage is a bit higher for indoor cats—they tend to be overweight or obese because they don’t get as much exercise. To help decrease your cat’s risk of diabetes, the most important thing is to keep them at a normal body weight. You should be able to easily feel their ribs, and there shouldn’t be a big paunch hanging down off their stomach. Your favorite veterinarian can help you determine the best food to feed your cat and the correct amount to help keep them at an ideal weight.

Yearly checkups are also very important so you can monitor for weight loss and other changes. If you notice your cat losing weight quickly, drinking more, or you’re finding litter box scooping more onerous, please make an appointment to see your vet. The sooner diabetes is diagnosed and treated, the more likely your cat could go into remission.

Photograph by Brenda Eckhardt

Lori Scarlett, DVM, is the owner and veterinarian at Four Lakes Veterinary Clinic. For more information, visit fourlakesvet.com .