A recent article published in Diabetes Care, confirms that Metformin has long-term protective effects against diabetes development in adults at greatest risk, especially those with higher HbA1c levels and women who have had gestational diabetes.

“Whether metformin should be used for diabetes prevention requires a careful balance of benefits and risks,” Marinella Temprosa, PhD, assistant research professor in the department of epidemiology and biostatistics at George Washington University, and colleagues wrote.

These findings were obtained from a long-term follow-up of the Diabetes Prevention Program (DPP) and the Diabetes Prevention Program Outcomes Study (DPPOS). Participants were randomly assigned to placebo, a lifestyle intervention or 850 mg metformin twice daily. In a 15-year follow-up analysis, Temprosa and colleagues evaluated data from the placebo (n = 1,082; mean age, 50.3 years; 69% women) and metformin (n = 1,073; mean age, 50.9 years, 66.2% women) groups. Although oral glucose tolerance tests and fasting plasma glucose were used to diagnose diabetes in the two previous studies, the researchers included diagnosis by HbA1c in post hoc analysis.

At 15 years, the metformin group had lower diabetes incidence rates by 17% compared with placebo based on OGTT and FPG diagnosis, and 36% by HbA1c. When OGTT and FPG were used as diagnostic tools, the researchers wrote that participants with higher FPG levels at baseline experienced an even greater effect from metformin (P = .0004). They also noted that metformin lowered diabetes incidence by 41% in women who previously had gestational diabetes (HR = 0.59; 95% CI, 0.42-0.84). In contrast, with HbA1c as the diagnostic marker, there were “comparable beneficial effects across all of the subgroups,” the researchers wrote.

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