After 15 years, use of metformin among women who’ve had gestational diabetes was associated with a 41% lower risk of developing type 2 diabetes, compared with an 11% reduced risk among women with no history of gestational diabetes, researchers reported. These latest findings come from the Diabetes Prevention Program (DPP) and its extension phase. This contrasts with an overall effect of metformin in reducing the risk of type 2 diabetes by 18% in the study cohort as a whole. Dr. David Nathan who was the study lead presented the results at the 77th ADA Scientific Sessions and stated that, “The overall results reinforce the long-lasting efficacy of metformin in reducing the development of diabetes and support its more widespread use as a prevention measure in those at high risk.” In the original analysis, metformin reduced the risk of future diabetes by 51% in women with a history of gestational diabetes. Two other subgroups of patients also seemed to gain greater benefit from metformin — those younger than 60 years of age and those with a BMI >35 kgm2. At the conclusion of the DPP, the placebo was stopped, and all patients were offered a slightly different lifestyle intervention. In addition, metformin continued to be provided to the people in the original metformin group. This extension phase — known as the Diabetes Prevention Program Outcomes Study (DPPOS) — was started in 2003 and is still ongoing, with 88% of the original volunteers still participating. Over time, the 31% reduction in diabetes risk initially seen with metformin waned to 18% by 10 years and has remained stable, so “an 18% reduction is the overall result, compared with people in the original placebo group,” Dr. Nathan pointed out. One of the clinical implications includes, considering which of their patients should receive metformin, clinicians should now be more likely to prescribe it to women with a history of gestational diabetes, who were shown in this study to have the biggest impact in terms of diabetes reduction. Dr. Nathan in conclusion added that, lifestyle modification should always be tried first. — American Diabetes Association (ADA) 2017 Scientific Sessions