Two classes of oral hypoglycemic drugs directly improve insulin action: biguanides (only metformin is currently available) and thiazolidinediones (TZDs). In the absence of contraindications, metformin is considered the first choice for oral treatment of type 2 diabetes (table 1). A 2006 consensus statement from the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD), updated in 2009 and 2012, proposed that metformin therapy (in the absence of contraindications) be initiated, concurrent with lifestyle intervention, at the time of diabetes diagnosis [1-3].
The pharmacology, efficacy, and side effects of metformin for the treatment of diabetes will be reviewed here. A general discussion of initial treatment of type 2 diabetes and the role of metformin in the prevention of diabetes, in the treatment of polycystic ovary syndrome, and in gestational diabetes are reviewed separately.
●(See "Initial management of blood glucose in adults with type 2 diabetes mellitus".)
●(See "Prevention of type 2 diabetes mellitus", section on 'Metformin'.)
●(See "Metformin for treatment of the polycystic ovary syndrome".)