PREVENT-DM Comparative Effectiveness Trial of Lifestyle Intervention and Metformin

Although the Diabetes Prevention Program and other clinical trials demonstrated the efficacy of intensive lifestyle interventions (ILI) and metformin to prevent type 2 diabetes, no studies have tested their comparative effects in pragmatic settings. This study was designed to compare the real-world effectiveness of ILI, metformin, and standard care among Hispanic women (Latinas) with prediabetes.

RCT.

Ninety-two Latinas, who had a mean hemoglobin A1c of 5.9%, BMI of 33.3 kg/m², and waist circumference of 97.4 cm (38.3 inches), were recruited from an urban community and randomly assigned to ILI, metformin, or standard care using 1:1:1 allocation. Data were collected from 2013-2015 and analyzed in 2016.

The 12-month ILI was adapted from the Diabetes Prevention Program's ILI and delivered by community health workers (promotoras) over 24 sessions. Metformin participants received 850 mg twice daily. Those randomized to standard care continued their regular medical care.

Weight and secondary outcomes (waist circumference, blood pressure, hemoglobin A1c, fasting plasma glucose, insulin, and lipids) were assessed at baseline and 12 months.

ILI participants demonstrated significantly greater mean weight loss (-4.0 kg, 5.0%) than metformin (-0.9 kg, 1.1%) and standard care participants (+0.8 kg, 0.9%) (p<0.001). The difference in weight loss between metformin and standard care was not significant. The ILI group experienced a greater reduction in waist circumference than standard care (p=0.001), and a marginal improvement in hemoglobin A1c compared with metformin and standard care (p=0.063).

In the first comparative effectiveness trial of diabetes prevention treatments, a 12-month ILI produced significantly greater weight loss than metformin and standard care among Latinas with prediabetes. These data suggest that ILI delivered by promotoras is an effective strategy for preventing diabetes in this high-risk group, which may be superior to metformin. Future pragmatic trials involving larger samples should examine differences in diabetes incidence associated with these treatments.