Diabetes Mellitus
Diabetes mellitus
Also known as: IDDM, NIDDM, Transient diabetes mellitus
CatDogUrgency: Moderate
Diabetes mellitus
Also known as: IDDM, NIDDM, Transient diabetes mellitus
In short
Diabetes mellitus is a common metabolic disorder in dogs and cats characterized by high blood sugar and glucose in the urine. While dogs almost always require lifelong insulin therapy, cats often experience a form of the disease that can sometimes go into remission with prompt, appropriate care.
TL;DR. Diabetes mellitus is a common metabolic condition where the body cannot properly regulate blood sugar, leading to increased thirst, urination, appetite, and weight loss that requires careful, lifelong management.
Diabetes mellitus affects both dogs and cats, but the underlying disease mechanisms differ between the two species.
Diabetes mellitus is a common metabolic disorder that affects how your pet's body converts food into energy. When a dog or cat digests food, their body breaks it down into glucose (sugar), which enters the bloodstream. Glucose is the primary fuel source for the body's cells. To enter these cells and provide energy, glucose requires a hormone called insulin, which is produced by the pancreas.
In a healthy pet, the pancreas releases insulin in response to rising blood sugar levels. In a diabetic pet, this system fails. This failure occurs due to either an absolute deficiency of insulin (the pancreas produces little to no insulin) or a relative deficiency (the body's cells become resistant to insulin, or the pancreas cannot produce enough to overcome the resistance). Without adequate insulin action, glucose builds up in the bloodstream, leading to persistent fasting hyperglycemia (high blood sugar) and glycosuria (sugar spilling over into the urine).
There is a significant difference in how this disease manifests in dogs compared to cats. In dogs, diabetes is almost always type 1 (insulin-dependent). In this form, the insulin-producing beta cells in the pancreas are permanently destroyed. As noted in a leading veterinary internal medicine reference:
"Virtually all dogs with diabetes have type 1 insulin-dependent diabetes mellitus (IDDM) at the time of diagnosis. Type 1 diabetes is characterized by hypoinsulinemia, essentially no increase [in insulin secretion]."
Conversely, cats more commonly develop type 2 diabetes (non-insulin-dependent or insulin-resistant diabetes). In cats, the pancreas still has some ability to produce insulin, but the body's tissues are resistant to it. Feline diabetes is often associated with obesity, chronic inflammation of the pancreas, or other hormonal imbalances. Crucially, because some pancreatic function remains, feline diabetes can sometimes be transient, meaning the cat may enter diabetic remission and temporarily or permanently stop needing insulin injections if treated early and aggressively.
The underlying causes of diabetes differ by species. In dogs, the destruction of pancreatic beta cells is typically an immune-mediated process, where the dog's own immune system mistakenly attacks and destroys these cells. Genetics play a major role, and certain breeds are far more susceptible than others.
In cats, the development of diabetes is closely linked to lifestyle and underlying physical changes in the pancreas. According to a standard veterinary internal medicine textbook:
"Common histologic abnormalities in cats with diabetes mellitus include islet-specific amyloidosis, β-cell vacuolation and degeneration, and chronic pancreatitis."
Amyloidosis refers to the abnormal deposition of a protein called amyloid in the pancreatic islets, which gradually destroys the insulin-producing cells. Obesity is a massive risk factor in cats, as excess fat tissue releases inflammatory chemicals that cause severe insulin resistance. Additionally, the use of certain medications, such as glucocorticoids (steroids) or progesterone-like drugs, can trigger or worsen diabetes in both species by blocking the action of insulin.
The signs of diabetes mellitus are directly related to the high concentration of glucose in the blood and its loss through the urine. When blood glucose levels exceed a certain threshold, the kidneys can no longer reabsorb it, and glucose spills into the urine. Glucose is osmotically active, meaning it pulls large amounts of water with it, leading to increased urination and subsequent dehydration, which drives increased thirst.
A plantigrade posture, where a cat walks flat on its hocks, is a classic sign of diabetic nerve damage.
If diabetes goes untreated or uncontrolled, it can progress to a life-threatening crisis called Diabetic Ketoacidosis (DKA). When cells cannot use glucose, the body breaks down fats at an extreme rate, producing acidic compounds called ketones. As a leading textbook explains:
", lethargy, anorexia, vomiting) ensue as ketonemia and metabolic acidosis develop and worsen, with the severity of these signs directly related to the severity of the metabolic acidosis and the nature of concurrent disorders that are often present."
If your diabetic pet begins vomiting, refuses food, becomes extremely weak, or has sweet, chemical-smelling breath, this is a medical emergency that requires immediate veterinary intervention.
Diagnosing diabetes mellitus is straightforward and relies on demonstrating two key findings simultaneously: persistent high blood sugar and sugar in the urine.
Your vet will perform the following diagnostic tests:
Urinalysis is a critical step in diagnosing diabetes, confirming the presence of glucose and checking for ketones.
Managing diabetes mellitus requires a consistent daily routine, dietary adjustments, and, in almost all cases, medication.
Insulin therapy is the cornerstone of managing diabetes. Because dogs have an absolute deficiency of insulin, they must receive insulin injections to survive. Cats also benefit most from immediate insulin therapy, which helps relieve "glucose toxicity" (a state where high blood sugar further damages the remaining pancreatic beta cells) and increases the chances of remission.
Insulin is administered via tiny, under-the-skin (subcutaneous) injections, typically twice a day, immediately after meals. Your vet will teach you how to give these injections, which most pets tolerate very well.
In dogs, managing insulin can become more challenging over the first few months of therapy. As a standard internal medicine reference notes:
"However, glycemic control becomes more difficult and insulin doses usually increase within 3 to 6 months of the start of treatment as residual functioning β cells are destroyed and endogenous insulin secretion declines."
Oral antidiabetic medications are generally not effective in dogs because dogs do not have functioning beta cells to stimulate. However, in cats with type 2 diabetes, oral medications may occasionally be considered if insulin therapy is absolutely impossible for the owner to perform, though they are less effective than insulin. These include:
Diet is a critical component of treatment. Diabetic dogs thrive on high-fiber, complex-carbohydrate diets that slow the absorption of glucose from the intestines. Diabetic cats, on the other hand, require a high-protein, ultra-low-carbohydrate diet, which mimics their natural carnivorous needs and helps reduce insulin resistance.
In cats, prompt diagnosis and treatment can lead to a resolution of the diabetic state. A leading reference describes this phenomenon:
"The clinician makes a correct diagnosis of diabetes mellitus; insulin therapy, discontinuation of insulin antagonistic drugs, and treatment of insulinantagonistic disorders improve hyperglycemia and insulin resistance; glucose toxicity resolves; β-cell function improves; insulin secretion returns; and an apparent IDDM state resolves."
If your cat enters remission, they may no longer require daily insulin injections, though they will still need a strict low-carbohydrate diet and close monitoring.
With dedicated care, diabetic pets can live happy, comfortable lives.
In dogs, the mean survival time is approximately 3 years from the time of diagnosis. However, this statistic is heavily influenced by the initial stabilization period. Dogs that survive the first 6 months of treatment can easily maintain an excellent quality of life for longer than 5 years with proper, consistent care.
While long-term survival statistics for cats are highly variable and depend on concurrent diseases, many diabetic cats live for several years post-diagnosis, especially those that achieve diabetic remission.
Even with good management, long-term complications can arise. In dogs, cataracts and subsequent blindness are very common and often unavoidable. Additionally, diabetic dogs are at a higher risk for developing high blood pressure. A study cited in a leading textbook notes:
"...the prevalence of hypertension to be 46% in 50 insulin-treated diabetic dogs... The development of hypertension was associated with the duration of diabetes and an increased albumin/creatinine ratio in the urine."
Your vet will regularly monitor your diabetic pet's blood pressure and kidney function to catch and manage these complications early.
Because canine diabetes is primarily an autoimmune disease, it is not currently preventable. However, keeping your dog at a healthy weight and ensuring they receive prompt treatment for any underlying hormonal diseases can help.
In cats, diabetes is highly preventable. Maintaining your cat at a lean, healthy body weight through a high-quality diet and regular exercise is the single most effective way to prevent insulin resistance. Additionally, avoiding the long-term or unnecessary use of corticosteroid medications can significantly reduce the risk of triggering diabetes in both dogs and cats.
Managing a diabetic pet requires vigilant monitoring. You should contact your veterinarian if you notice:
Seek emergency veterinary care immediately if your pet exhibits:
Genetics play a strong role in the development of diabetes. If you own one of the following breeds, you should be especially vigilant for the early signs of increased thirst and urination:
Regular veterinary checkups and routine blood and urine screenings are highly recommended for these breeds, especially as they enter their senior years.
Treatment must be prescribed by a licensed veterinarian based on your pet. Specific drug doses are intentionally not shown here.
Diabetes mellitus is a common metabolic disorder in dogs and cats characterized by high blood sugar and glucose in the urine. While dogs almost always require lifelong insulin therapy, cats often experience a form of the disease that can sometimes go into remission with prompt, appropriate care.
Polydipsia、Polyphagia、Polyuria、Weight loss、Blindness、Cataracts、Lethargy、lack of grooming behavior
Glycosuria、Persistent fasting hyperglycemia、Serum fructosamine concentration、Serum pancreatic lipase immunoreactivity、Urine reagent test strips
Treatment must be prescribed by a licensed veterinarian based on your pet. Specific drug doses are intentionally not shown here.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
Peqaboo’s AI helps you track symptoms, understand lab reports, and know when to see a vet.
Get the Peqaboo app