Cats develop diabetes when their bodies can no longer produce enough insulin or respond to it properly. The vast majority of diabetic cats have type 2 diabetes, the same form most common in humans, where cells gradually lose their sensitivity to insulin. An estimated 0.2% to 1.2% of domestic cats are affected, making it one of the most common hormonal disorders in cats.
Obesity Is the Biggest Driver
Excess body fat doesn’t just sit there. In overweight cats, fat tissue actively recruits immune cells called macrophages, which produce inflammatory signals. These signals interfere with insulin at a cellular level: they shut down genes that help cells respond to insulin, and they trigger fat cells to release fatty acids into the bloodstream. High circulating fatty acids further reduce insulin sensitivity in muscles and other tissues. The result is a vicious cycle where the pancreas has to pump out more and more insulin to keep blood sugar in check.
Over months or years, the pancreas can’t keep up with this escalating demand. The insulin-producing cells become exhausted, and a toxic protein called amyloid builds up in the pancreas, permanently damaging it. By the time a cat shows symptoms like increased thirst and weight loss, substantial pancreatic damage has often already occurred.
Indoor Lifestyle and Inactivity
A study comparing 96 diabetic cats with 192 healthy matched controls found that indoor confinement and low physical activity were both significant, independent risk factors for type 2 diabetes. Cats that lived entirely indoors and got little exercise were measurably more likely to develop the disease. This held true regardless of what type of food (wet or dry) the cats ate. The proportion of dry food in the diet, often blamed as a culprit, was not independently correlated with diabetes risk in this study.
This makes biological sense. Physical activity helps muscles absorb glucose from the blood, improving insulin sensitivity. Cats evolved as active hunters, and the combination of confinement, boredom, free-feeding, and minimal movement creates ideal conditions for weight gain and metabolic dysfunction.
What About Carbohydrates?
There’s a popular belief that high-carbohydrate diets cause diabetes in cats because they’re obligate carnivores. The reality is more nuanced than many pet food forums suggest. Cats lack certain liver enzymes and taste receptors found in omnivores, and their bodies run gluconeogenesis (making glucose from protein) more or less continuously. These differences fueled concern that carb-heavy diets would overwhelm feline metabolism.
However, studies measuring actual glucose metabolism show that cats can digest properly cooked carbohydrates at rates exceeding 90%, and they retain the ability to moderate their own glucose production. Research published in the Journal of the American Veterinary Medical Association concluded bluntly: “There is no evidence to conclude that high carbohydrate diets lead to diabetes mellitus in cats.” Even cats fed very high-carbohydrate diets in controlled studies did not develop pathological blood sugar levels.
That said, once a cat already has diabetes, low-carbohydrate diets (providing roughly 5% to 26% of calories from carbohydrates) do improve blood sugar control and increase the chances of remission. So carbs matter for managing the disease, even if they don’t appear to cause it on their own.
Breed and Genetic Risk
Some cats are genetically predisposed. Burmese cats are consistently overrepresented among diabetic cats in multiple studies across different countries, suggesting a hereditary component to their risk. Male cats and neutered cats of both sexes also develop diabetes at higher rates, likely due to the metabolic changes that come with reduced sex hormones and the weight gain that often follows neutering.
Most cats diagnosed with diabetes are middle-aged or older, typically over 7 years. Age-related decline in pancreatic function, combined with years of gradual weight gain, makes older cats particularly vulnerable.
Medications That Can Trigger Diabetes
Certain drugs push cats into a diabetic state by directly opposing insulin’s effects. Corticosteroids (commonly prescribed for allergies, asthma, and inflammatory bowel disease) and progestins (synthetic hormones sometimes used for behavioral issues) are the main offenders. These medications increase insulin resistance, and in a cat that’s already borderline, this can tip the balance into full-blown diabetes. In some cases the diabetes resolves after the medication is stopped, but in others the pancreatic damage becomes permanent.
Hidden Underlying Diseases
A significant proportion of cats with hard-to-control diabetes actually have an underlying condition called acromegaly, where a pituitary tumor causes the body to overproduce growth hormone. Growth hormone directly opposes insulin, creating severe, treatment-resistant diabetes. Two separate studies found acromegaly to be surprisingly common among diabetic cats, particularly those needing unusually high insulin doses.
Chronic pancreatitis, where ongoing low-grade inflammation slowly destroys pancreatic tissue, is another hidden contributor. Because pancreatitis in cats is notoriously subtle (cats rarely vomit or show obvious pain the way dogs do), it can smolder for years, quietly eroding the organ’s ability to produce insulin.
How Diabetes Gets Diagnosed
Diagnosis isn’t as simple as a single blood test. Cats are notorious for developing “stress hyperglycemia,” where a vet visit alone can spike blood sugar to diabetic-looking levels. A cat’s kidneys start spilling glucose into the urine when blood sugar exceeds roughly 250 to 300 mg/dL, so finding sugar in the urine is one clue. But confirming true diabetes usually requires a fructosamine test, which measures average blood sugar over the previous one to two weeks and isn’t affected by a stressful car ride.
Remission Is Possible With Early Action
Unlike dogs, many diabetic cats can actually go into remission, meaning they no longer need insulin injections. A large study of 174 cats treated with insulin and home blood sugar monitoring found that 47% achieved remission, with a median time of about 93 days. Early, aggressive treatment gives the pancreas a chance to recover before amyloid deposits cause irreversible damage. Cats diagnosed and treated promptly, switched to a low-carbohydrate diet, and brought to a healthy weight have the best odds of eventually coming off insulin entirely.
The window matters. Cats that have been diabetic for months without treatment have less functional pancreatic tissue left to salvage, making remission less likely the longer the disease goes unmanaged.