When blood sugar regulation fails, every organ system is at risk. Diabetes mellitus is a group of metabolic diseases characterized by chronically elevated blood glucose resulting from inadequate insulin production, impaired insulin action, or both.

Type 1 diabetes involves autoimmune destruction of insulin-producing cells and requires lifelong insulin. Type 2 diabetes is driven mainly by insulin resistance and relative insulin deficiency and is strongly linked to obesity and inactivity. Gestational diabetes appears during pregnancy. Diagnosis rests on fasting glucose, oral glucose tolerance testing, or glycated hemoglobin.

Management combines lifestyle measures, glucose monitoring, and medications that range from oral agents to insulin. Good control reduces risks of eye, kidney, nerve, and cardiovascular damage. Education in self-management is as important as any drug.

• Metabolic disease with chronic high blood glucose
• Results from insulin deficiency or resistance
• Includes type 1, type 2, and gestational forms
• Managed by lifestyle, monitoring, and medication