Diabetes Mellitus

Diabetes mellitus is a group of metabolic disorders characterized by chronic hyperglycaemia resulting from impaired insulin secretion, insulin action or both. To see why the disease behaves the way it does, start with what insulin normally does. Insulin is released by pancreatic beta cells after a meal, and it promotes glucose uptake in skeletal muscle and adipose tissue, suppresses hepatic glucose production, inhibits lipolysis and ketogenesis, supports protein synthesis and energy storage, and moves potassium into cells. When insulin is missing or ineffective, glucose stays in the blood while the cells behind it are starved of fuel. The body then breaks down fat, and without enough insulin to restrain it, that fat breakdown produces ketones. So the same single defect explains both the chronic problem (glucose-related organ damage) and the acute one (ketoacidosis). Between meals insulin secretion falls and glucagon helps maintain glucose availability. Other hormones raise glucose or reduce insulin sensitivity: cortisol, epinephrine and growth hormone. Incretin hormones such as GLP-1 enhance glucose-dependent insulin secretion and suppress glucagon, which is the basis for GLP-1 receptor agonist therapy. The practical...