Diabetes Mellitus in Dogs

Key Takeaways

Diabetes mellitus, or diabetes, is a common hormonal disorder of dogs, primarily caused by low or absent levels of insulin in the bloodstream. 

• The main symptoms associated with diabetes mellitus include excessive food intake, thirst, and urination, and weight loss despite a good appetite

• Secondary conditions that may occur with diabetic dogs include hypoglycemia, cataracts, and diabetic ketoacidosis

• Symptoms associated with these secondary conditions may include lethargy, wobbliness, seizures, blindness, and lack of appetite

• Diabetes mellitus is diagnosed by measuring consistently high glucose levels in the blood or urine

• Treatment usually consists of daily, life-long insulin injections

• Dietary management is also an important aspect in controlling diabetes

• Prognosis is good as long as monitoring and management requirements are met

A Closer Look: What is Diabetes Mellitus in Dogs?

Diabetes occurs when there is insufficient insulin in the body. As insulin is required for glucose uptake into tissues, low levels of insulin leads to high levels of circulating glucose in the bloodstream. Glucose (sugar) is normally the first energy source used by cells and tissues. When lack of insulin makes glucose unavailable, fats and proteins are metabolized to meet energy requirements. Excessive breakdown of fats produces high levels of ketones, which give the breath a strong odor similar to fingernail polish remover. 

Diabetes mellitus is one of the most common hormone disorders in dogs. It is a serious disease that can lead to secondary conditions, including the life-threatening condition, diabetic ketoacidosis, if left untreated. 

With early detection and treatment, dogs have a good prognosis. Treatment can be cumbersome as daily injections and repeated veterinary visits are for monitoring and medication adjustments are required. When treatment is delayed, secondary conditions are more likely and medical management becomes more complicated.

Risk Factors

Diabetes is typically diagnosed in middle-aged dogs. Additional risk factors for the development of diabetes in dogs include: 

• Intact females 

• Certain breeds (Cocker spaniels, Samoyeds, miniature schnauzers, Cairn terriers, and Yorkshire terriers) 


Excessively high levels of circulating glucose can negatively impact vision by disrupting the clarity of the lens. This disruption of lens clarity leads to cataracts and blindness in almost all unregulated diabetic patients. 

Other common conditions that develop as a result of high circulating glucose levels include: 

Urinary tract infections • Skin and ear infections

Insulin injections are the cornerstone of therapy for diabetes, but dosing must be precise.  Low blood sugar (hypoglycemia) is the most common complication of treatment for diabetes, presenting with symptoms such as:

Weakness/sleepiness • Dull mental state; being poorly responsive • Wobbliness (ataxia)

• Loss of consciousness • Seizures 

Hypoglycemia warrants immediate veterinary consultation as it can be fatal.

In uncontrolled, advanced stages of diabetes, a potential severe, life-threatening complication is diabetic ketoacidosis. These patients often appear lethargic, are unwilling to eat, and require immediate veterinary attention.

Possible Causes

Causes of diabetes include: 

• Immune-mediated destruction of the insulin-producing cells in the pancreas (often genetically-linked)

Pancreatitis • Hyperadrenocorticism (Cushing’s disease) • Pregnancy

Main Symptoms

The primary symptoms of diabetes mellitus are

Increased thirst • Increased hunger • Increased urinationWeight loss

Testing and Diagnosis

Diabetes is diagnosed based on symptoms and blood glucose levels after fasting. Glucose may also be detected in the urine when blood levels are consistently high. 

Tests a veterinarian may perform to diagnose diabetes, as well as detect other commonly associated conditions, include: 

• Physical exam • Blood work • Urinalysis

Steps to Recovery

Unlike humans, all dogs require insulin injections for treatment for diabetes. After the correct type and dose of insulin are determined by a veterinarian, injections can be easily administered from home with instruction. Injections are typically administered twice daily, after a meal.

It is important not to alter the insulin type or dose without veterinary consultation as there are different types of insulins, and insulin doses are patient-dependent. Dietary management is also important in diabetic patients to avoid spikes in glucose throughout the day. A high fiber diet and minimizing treat intake may be recommended to regulate blood sugar levels. 

Diabetes is associated with increased incidence of urinary tract infection, and any source of infection interferes with glucose metabolism. Ongoing diagnostics and treatment for associated conditions are an additional consideration in successful diabetes management. 

The management and treatment of diabetes mellitus is life-long. From determining the dose of insulin required, to intermittent blood glucose monitoring (in-clinic or at home), and potential readjustment of insulin dose in the future, multiple follow-up visits are required.


Many factors, including genetics, likely contribute to the development of diabetes in dogs. Preventing risk factors such as obesity, spaying female dogs, and having regular veterinary visits to detect diabetes early may help prevent the severity of disease.

Is Diabetes Mellitus Common in Dogs?

Diabetes mellitus is common in dogs.

Typical Treatment

• Insulin injections • Dietary management • Weight management • Spaying female dogs

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