Lifestyle programs show no significant diabetes incidence reduction in 14 studies of at-risk individuals

BACKGROUND: Prediabetes is a precursor of type 2 diabetes mellitus (T2DM), and lifestyle modifications are key preventive strategies. Primary care is central to prevention efforts, including screening, diagnosis, and follow-up. PURPOSE: This systematic review and meta-analysis aimed to evaluate the effectiveness of lifestyle interventions delivered in primary care to patients at elevated risk of developing T2DM. DATA SOURCES: We searched Medline and Embase from inception to 28 March 2024. STUDY SELECTION: We screened 639 records and included 14 eligible studies of lifestyle-based diabetes prevention programs. Eligible participants had prediabetes or high diabetes risk scores, and interventions were delivered in primary care. DATA EXTRACTION: Outcomes included diabetes incidence, glycemic and anthropometric indicators, physical activity, and diet. DATA SYNTHESIS: Pooled mean differences (MD) were estimated using inverse variance methods; leave-one-out cross-validation (LOOCV) addressed heterogeneity (>50%). Meta-analysis found no significant effects on diabetes incidence (relative risk 0.82; 95% CI 0.65-1.02), and pooled MD on HbA1c (MD -0.41, 95% CI -0.94 to 0.12), fasting glucose, 2-h glucose, body weight, BMI, waist circumference (MD -1.13, 95% CI -2.40 to 0.13), or systolic and diastolic blood pressure. LOOCV identified one study driving heterogeneity in several outcomes. LIMITATIONS: English-only publications may reduce generalizability. CONCLUSIONS: This review found no significant differences in diabetes incidence or other key indicators of T2DM, with certainty of evidence varying from moderate to low. Future studies should test integrated screening, referral, and social support strategies in routine care for high-risk groups.