Metformin Drug Classification
Metformin is classified as a biguanide antihyperglycemic agent. 1
Primary Classification
- Metformin belongs to the biguanide class of medications, which represents its fundamental chemical and pharmacological classification 2, 1
- The FDA drug label specifically describes metformin as "the antihyperglycemic agent metformin, which is a biguanide" 1
Mechanism of Action
The biguanide classification reflects metformin's specific mechanisms:
- Decreases hepatic glucose output as its primary mechanism 2
- Enhances primarily hepatic and muscle insulin sensitivity without directly affecting β-cell function 2
- Does not promote insulin secretion, distinguishing it from sulfonylureas and meglitinides 2
Clinical Context
Understanding metformin's classification as a biguanide is clinically important because:
- Biguanides work differently than other oral antidiabetic drug classes (sulfonylureas, thiazolidinediones, DPP-4 inhibitors, SGLT2 inhibitors, GLP-1 receptor agonists) 2
- This classification explains why metformin carries low hypoglycemia risk compared to insulin secretagogues 2
- The biguanide mechanism accounts for metformin's weight-neutral or weight-loss effects, unlike sulfonylureas or thiazolidinediones that cause weight gain 2
Important Safety Consideration
- The biguanide class carries a theoretical risk of lactic acidosis, which is why metformin is contraindicated in patients with impaired renal function, hepatic disease, or hypoxemic conditions 2