Diabetes mellitus is a group of metabolic diseases characterized by high blood sugar levels, which result from defects in insulin secretion, or action, or both.
Diabetes mellitus, commonly referred to as diabetes, means "sweet urine." Elevated levels of blood glucose (hyperglycemia) lead to spillage of glucose into the urine, hence the term sweet urine.
Normally, blood glucose levels are tightly controlled by insulin, a hormone produced by the pancreas. Insulin lowers the blood glucose level. When the blood glucose elevates (for example, after eating food), insulin is released from the pancreas to normalize the glucose level.
In patients with diabetes mellitus, the absence or insufficient production of insulin causes hyperglycemia.
Diabetes mellitus is a chronic medical condition, meaning it can last a lifetime.