Diabetes affects a surprisingly wide range of animals, from household pets like dogs and cats to wild dolphins, primates, and even reptiles. The disease works differently across species, though. Some animals develop a condition nearly identical to human Type 1 diabetes, others mirror Type 2, and a few have evolved metabolic quirks that make them uniquely vulnerable to sugar in ways most mammals are not.
Dogs: Mostly Type 1
At least 50% of diabetic dogs have Type 1 diabetes, where the immune system destroys the insulin-producing cells in the pancreas. Another 28% of cases result from extensive pancreatic damage, most likely from chronic pancreatitis. Notably, there is no published evidence that true Type 2 diabetes occurs in dogs at all, or that obesity is a direct risk factor for canine diabetes. This sets dogs apart from most other species on this list.
The symptoms look much like they do in humans: increased thirst, frequent urination, a bigger appetite despite losing weight. If the disease progresses to diabetic ketoacidosis, a dangerous complication, dogs become weak and lethargic, stop eating, and may vomit.
Genetics play a major role in which dogs are affected. A study in the Journal of the American Veterinary Medical Association found that Samoyeds have nearly 12 times the odds of developing diabetes compared to mixed-breed dogs. Miniature Schnauzers come in close behind at roughly 10 times the risk. Miniature Poodles, Pugs, and Toy Poodles round out the high-risk group, each with three to four times the average odds. If you own one of these breeds, it’s worth knowing the early signs.
Cats: Type 2 and Sometimes Reversible
Type 2 diabetes is the most common form in cats, making feline diabetes more metabolically similar to the human epidemic than canine diabetes is. Overweight, sedentary indoor cats are the typical patients. Their bodies still produce insulin but can’t use it effectively, or don’t produce enough to keep up with demand.
One hopeful difference from dogs: cats can sometimes go into remission. Diabetic remission means a cat no longer needs insulin injections and maintains normal blood sugar on its own. A systematic review found that remission has been documented with a variety of insulin types and dietary approaches, though no single factor reliably predicts which cats will achieve it. Reducing dietary carbohydrates appears promising but hasn’t been confirmed with strong clinical trials. The evidence overall is moderate to poor, largely because well-designed studies are lacking.
Hormonal conditions can also push cats into diabetes. Nearly 80% of cats with Cushing’s disease (where the body overproduces cortisol) develop concurrent diabetes, often with significant insulin resistance. In dogs, that overlap is much smaller, around 10%. The excess cortisol drives blood sugar up by increasing glucose production in the liver while simultaneously blocking insulin’s effects in tissues throughout the body.
Horses: Insulin Resistance, Not Classical Diabetes
Horses don’t typically develop diabetes in the way dogs and cats do. Instead, they develop equine metabolic syndrome, a condition centered on insulin dysregulation. The core problem is a disturbed relationship between circulating glucose and insulin. After eating carbohydrate-rich feeds or pasture grasses high in sugar, affected horses secrete excessive amounts of insulin. Their tissues may also respond poorly to the insulin that’s circulating, creating a feedback loop.
The condition alters fat metabolism too, with elevated blood triglycerides, increased leptin (a hormone linked to appetite and fat storage), and decreased adiponectin (a protein that helps regulate glucose). A visible “cresty neck” and general obesity are common in affected horses, but neither is required for diagnosis, and lean horses can have insulin dysregulation as well. The most dangerous consequence is laminitis, a painful and potentially crippling inflammation of the tissues inside the hoof.
Degus: Built to Fail on Sugar
Degus, small rodents native to Chile that are increasingly popular as pets, are one of the most diabetes-prone animals known. The reason is biochemical: degu insulin is only 1% to 10% as biologically active as the insulin of most other mammals. Their bodies evolved on a diet of tough, fibrous plants naturally low in sugars and starches, so they never needed potent insulin signaling.
When kept as pets or in laboratories and fed even slightly more carbohydrates than their wild diet provides, degus rapidly develop high blood sugar. Chronic exposure to fruit sugars causes full-blown diabetes accompanied by kidney damage and cataracts. For degu owners, this means avoiding fruit, sugary treats, and standard rodent pellets designed for rats or hamsters. A hay-based diet with limited fresh vegetables is essential.
Primates: A Natural Mirror of Human Diabetes
Several primate species develop spontaneous diabetes that closely resembles human Type 2. Black Celebes macaques are the most striking example: among mature animals, at least 50% show mild to moderate blood sugar problems, and about 10% are overtly diabetic at any given time. Cynomolgus macaques develop spontaneous diabetes at a rate of 1 to 2%, while rhesus macaques tend to become diabetic in middle age (around 15 years old and beyond), particularly if they become obese. Squirrel monkeys also show a relatively high frequency of glucose intolerance.
These primates develop diabetes along a progression that looks strikingly familiar: weight gain in middle age, rising insulin resistance, and eventually the inability of the pancreas to keep up. This makes them valuable research models, but it also means that primates in zoos and sanctuaries face real diabetes risk if their diets include too much fruit or processed food.
Dolphins: Diabetes They Can Switch Off
Bottlenose dolphins display metabolic responses consistent with Type 2 diabetes, including sustained high blood sugar and high insulin levels after eating. Their fasting insulin levels mimic those found in humans with insulin resistance. After both high-protein and high-sugar meals, dolphins show prolonged blood sugar elevation alongside changes in blood chemistry that parallel human diabetes markers: elevated platelets, shifts in liver enzymes, decreased uric acid, and a trend toward metabolic acidosis.
The fascinating part is that dolphins appear to toggle this diabetes-like state on and off. After an overnight fast, their metabolic markers normalize. With daily feeding, the diabetic pattern returns. Researchers believe this may be an evolutionary adaptation to a high-protein, fish-based diet that requires managing large glucose loads differently than land mammals do. Dolphins with iron overload (hemochromatosis) show even higher post-meal insulin levels, suggesting the system can tip toward dysfunction, much as it does in humans.
Reptiles and Birds
True diabetes has rarely been documented in reptiles and remains poorly understood. High blood sugar is uncommon in reptiles as a clinical finding, and when it does appear, it’s more often related to other metabolic conditions, systemic illness, or normal physiological variation tied to season, feeding status, or body condition than to pancreatic disease.
That said, spontaneous diabetes does occur. Over 35 years of practice, one veterinary specialist documented cases in reptiles that showed destruction of insulin-producing cells in the pancreas, sometimes from amyloid deposits and sometimes from severe inflammation. One notable case involved a red-eared slider turtle with a blood glucose level of 830 mg/dL (normal for most reptiles is far lower), which presented lethargic and refusing food for three weeks.
Diabetes in birds is documented in veterinary literature but studied far less than in mammals. The pancreatic anatomy of birds differs from mammals in ways that may affect how the disease develops. Reptile and bird pancreases organize their insulin-producing and glucagon-producing cells differently, which likely contributes to the distinct metabolic patterns seen across these groups.
Why the Type Varies by Species
The split between Type 1 and Type 2 across species comes down to evolutionary pressures and pancreatic biology. Dogs, whose immune systems readily attack their own insulin-producing cells, lean toward Type 1. Cats, primates, and dolphins, whose problems center on insulin resistance and overworked pancreatic cells, lean toward Type 2. Degus represent a third category entirely: an animal whose insulin molecule is so structurally different from other mammals’ that it simply cannot handle dietary sugar, regardless of immune function or obesity.
Hormonal diseases create yet another pathway. Cushing’s disease, acromegaly (excess growth hormone), and other endocrine conditions can cause secondary diabetes in dogs, cats, horses, and ferrets by flooding the body with hormones that oppose insulin’s effects. In cats especially, the overlap between Cushing’s disease and diabetes is remarkably high, making hormonal screening an important part of managing a newly diabetic cat that doesn’t respond well to insulin.