Metformin

Biguanide

Drug Class: Biguanide
Mechanism of Action (MOA): ↓ hepatic gluconeogenesis and ↑ peripheral insulin sensitivity (does not stimulate insulin secretion).
Black Box Warning: Lactic acidosis (rare) — risk rises with renal impairment, hypoxia, IV contrast, and sepsis.
Clinical Notes: First-line for type 2 DM; weight-neutral, no hypoglycemia as monotherapy. GI upset and B12 deficiency. Hold around iodinated contrast.
Source: FDA label (DailyMed)