Diabetes mellitus
- Clinically significant glucose intolerance
- Chronic disease caused by absolute or relevant deficiency of insulin and therefore disorders of carbohydrate metabolism
- Occurs in most species, most commonly in dog and cat
Aetiology
Can be caused by
- Absolute deficiency of insulin
- Antagonism of insulin by hormones from the adrenal and thyroid glands, anterior pituitary causing high levels of blood glucose
- Complication of pancreatic fibrosis
- Insulin binding antibodies, insulinase and plasma antagonists imbalance
- Chronic insulin resistance results in hyperinsulinism leading to islet exhaustion
Clinical signs
- Hyperglycaemia
- Polyuria
- Polydypsia
- Polyphagia
- Weight loss
- Muscle wasting (but some animals may present obese)
- Hepatomegaly
- Cataracts (dogs)
- Later stages when becoming ketoacidotic
- Dehydration
- Depression
- Inappetance
- Vomiting
- Diarrhoea
- Ketotic breath
- Ketonuria
- Metabolic acidosis
- Reduced cardiac output (due to loss of water and sodium), reduced blood pressure and renal flow causing circulatory collapse, coma and death
Pathology
- Pancreas appers normal or reduced in size due to fibrosis
- In cats, amyloidosis is sometimes present in the islets
- Fatty change is consistently present in the liver and kidneys
- The lens in the eye is often opaque due to deposition of sorbitol causing it to swell (glucose is converted into sorbitol once the glycolytic pathway is saturated)