Diabetes mellitus is a syndrome of impaired carbohydrate, fat, and protein metabolism caused by either lack of insulin secretion or decreased sensitivity of the tissues to insulin. There are two general types of dia-betes mellitus:
1. Type I diabetes, also called insulin-dependent diabetes mellitus (IDDM), is caused by lack ofinsulin secretion.
2. Type II diabetes, also called nonâ€“insulin-dependent diabetes mellitus (NIDDM), is caused by decreasedsensitivity of target tissues to the metabolic effect of insulin. This reduced sensitivity to insulin is often called insulin resistance.
In both types of diabetes mellitus, metabolism of all the main foodstuffs is altered. The basic effect of insulin lack or insulin resistance on glucose metabolism is to prevent the efficient uptake and utilization of glucose by most cells of the body, except those of the brain. As a result, blood glucose concentration increases, cell utilization of glucose falls increasingly lower, and utilization of fats and proteins increases.