Hyperglycaemia in pets

What It Is

Hyperglycaemia means a blood glucose reading came back higher than normal on bloodwork, not something visible at home. Cats show a strong stress response: the excitement of a car ride and vet visit alone can push glucose up temporarily, a pattern well known enough to have its own name, stress hyperglycaemia. Dogs show this effect less dramatically, so a high reading in a dog more often reflects a genuine problem. A single number rarely tells the whole story.

Common Causes

Diabetes mellitus, where the body cannot produce or properly use insulin, is the leading cause of persistent hyperglycaemia in dogs and cats. Stress is a major factor in cats and can produce readings just as high as true diabetes on one test. Cushing's disease and steroid medications raise glucose as a side effect. Pancreatitis, obesity-related insulin resistance, and recent food intake can each nudge glucose upward without indicating chronic disease.

When It Is an Emergency

A very high reading combined with vomiting, lethargy, rapid breathing, or unusually sweet-smelling breath suggests diabetic ketoacidosis, a life-threatening complication needing immediate hospital care. A pet already diagnosed with diabetes that suddenly stops eating or becomes weak should be seen the same day rather than waiting for a scheduled recheck, since the balance between food and insulin can shift quickly.

What the Vet Will Do

To separate a stress spike from true diabetes, the vet often repeats the glucose test once the pet has calmed down, or runs a fructosamine test, which reflects average blood sugar over the preceding two to three weeks. A urinalysis checks for glucose and ketones, both supporting evidence for diabetes. If diabetes is confirmed, further bloodwork looks for contributing conditions such as pancreatitis or Cushing's disease.

Home Care and Prevention

A consistent feeding and exercise schedule makes blood sugar far more predictable and easier to manage with insulin. Maintaining a healthy body weight lowers the risk of diabetes developing, particularly in overweight cats. Watching for early increased thirst and urination allows diabetes to be caught before it progresses to ketoacidosis. Sticking closely to the vet's monitoring schedule gives the most reliable picture of control.