diabetes mellitus

Imagine the bloodstream as a delivery system carrying sugar (glucose) to every cell, and insulin as the key that unlocks the cell door so the sugar can enter and be used for energy. In diabetes mellitus, either there is no key, or the locks have grown stiff and stop responding. Sugar piles up in the blood instead of getting into the cells, leaving the body energy-starved despite a sweet flood in the vessels.

Medically, diabetes mellitus is a group of metabolic disorders united by chronic hyperglycemia, resulting from defective insulin secretion, defective insulin action, or both. The name comes from Greek and Latin: ‘diabetes’ (to pass through, for the heavy urination) and ‘mellitus’ (honey-sweet, because the urine contains spilled-over glucose). The main forms are type 1, type 2, gestational, and various monogenic and secondary types.

Diagnosis rests on objective thresholds: a fasting plasma glucose of 7.0 mmol/L (126 mg/dL) or higher, a 2-hour value of 11.1 mmol/L (200 mg/dL) or higher on an oral glucose tolerance test, an HbA1c of 6.5% or higher, or a random glucose of 11.1 mmol/L with classic symptoms. Left uncontrolled, persistent hyperglycemia damages small and large blood vessels, producing the eye, kidney, nerve, heart, and circulatory complications that make diabetes a leading cause of disability worldwide.