Nutritional management of diabetes mellitus in dogs and cats

Diabetes mellitus (DM) is a major endocrine disorder in companion animals caused by an absolute or relative deficiency of insulin. Dogs primarily present with Type I DM (>95% of cases), characterized by immune-mediated beta-cell destruction requiring exogenous insulin. Conversely, cats predominantly develop Type II DM (>80% of cases), driven by peripheral insulin resistance, amyloid deposition in pancreatic islets, and glucose toxicity. Nutritional management plays a vital role in optimizing glycemic control alongside insulin therapy. Distinct physiological requirements demand species-specific dietary formulation: diabetic dogs benefit from high-fiber, complex carbohydrate-based diets (≥40% calories from starch) to slow postprandial glucose absorption, whereas diabetic cats thrive on high-protein (≥30% DM), low-carbohydrate regimens that reduce hepatic gluconeogenesis and postprandial hyperglycemia. Strict consistency in dietary composition, timing, and caloric control is mandatory. This article reviews the pathophysiology, classification, macronutrient guidelines, species differences, and dietary restrictions for managing canine and feline diabetes mellitus.