Results from the long-term follow-up of participants in the landmark Diabetes Prevention Program (DPP) that enrolled patients between 1996 and 2001 were recently published. Metformin use over 15 years was compared to placebo in patients who were at high risk for developing diabetes. A new type 2 diabetes diagnosis was indicated using fasting glucose or 2-hour glucose tolerance as in the original study, or by measuring A1C. Patients who continued to take metformin had a 17% lower risk of developing diabetes or a 36% lower risk if diagnosed by A1C. Even stronger diabetes prevention effects were seen in some subgroups. Women with a history of gestational diabetes had a 41% lower risk compared to women who did not have gestational diabetes. Patients with higher baseline fasting glucose or A1C also benefited more from taking metformin.
Metformin is inexpensive and usually well tolerated. It should be considered for diabetes prevention, particularly for patients with an elevated baseline A1C and for women who had gestational diabetes.
• Diabetes Prevention Program Research Group. Diabetes Care 2019;42:601-608.