Review of Metformin Use for Type 2 Diabetes Prevention

Context: Prediabetes is prevalent and significantly increases lifetime risk of progression to type 2 diabetes. This review summarizes the evidence surrounding metformin use for type 2 diabetes prevention. Evidence acquisition: Articles published between 1998 and 2017 examining metformin use for the primary indication of diabetes prevention available on MEDLINE. Evidence synthesis: Forty articles met inclusion criteria and were summarized into four general categories: (1) RCTs of metformin use for diabetes prevention (n=7 and n=2 follow-up analyses); (2) observational analyses examining metformin use in heterogeneous subgroups of patients with prediabetes (n=9 from the Diabetes Prevention Program, n=1 from the biguanides and the prevention of the risk of obesity [BIGPRO] trial); (3) observational analyses examining cost effectiveness of metformin use for diabetes prevention (n=11 from the Diabetes Prevention Program, n=1 from the Indian Diabetes Prevention Program); and (4) real-world assessments of metformin eligibility or use for diabetes prevention (n=9). Metformin was associated with reduced relative risk of incident diabetes, with the strongest evidence for use in those at highest risk (i.e., aged <60 years, BMI ≥35, and women with histories of gestational diabetes). Metformin was also deemed cost effective in 11 economic analyses. Recent studies highlighted low rates of metformin use for diabetes prevention in real-world settings. Conclusions: Two decades of evidence support metformin use for diabetes prevention among higher-risk patients. However, metformin is not widely used in real-world practice, and enhancing the translation of this evidence to real-world practice has important implications for patients, providers, and payers.