Randomized controlled trials have shown the efficacy of lifestyle interventions or metformin for reducing diabetes conversion among individuals with impaired glucose tolerance (IGT). The American Diabetes Association (ADA) and the International Diabetes Federation recommend stepwise diabetes prevention (lifestyle modification plus metformin when risk remains elevated) for individuals with any form of prediabetes, defined as isolated IGT (iIGT), isolated impaired fasting glucose (iIFG), or IFG+IGT. However, no large diabetes prevention trial has compared the effects of diabetes prevention across the prediabetes spectrum, and no study has tested the effectiveness of the stepwise diabetes prevention recommendations.
The incredible diabetes burden reflects our failure to translate proven evidence for prevention into action on a wider scale. Worldwide, 415 million people have diabetes, and this number will reach 642 million by 2040. Most individuals with diabetes, 75%, live in low- and middle-income countries (LMICs), where the condition has especially marked effects on health and economic prosperity.
The Diabetes Community Lifestyle Improvement Program (D-CLIP) is a randomized controlled, diabetes prevention trial in adults with iIGT, iIFG, or IFG+IGT in which standard of care is compared with a culturally tailored lifestyle education curriculum based on the U.S. Diabetes Prevention Program (DPP) plus stepwise addition of metformin when needed. D-CLIP was conducted in Asian Indians, a population at elevated risk for developing diabetes even at younger ages and lower BMIs and possibly with dual susceptibility to insulin resistance and early β-cell dysfunction. In this study we tested the effectiveness of guideline-based, stepwise diabetes prevention by comparing the incidence of diabetes between control and intervention participants and by determining whether intervention effects differ across baseline prediabetes type, HbA1c level, age, sex, BMI level, or family history of diabetes.