Effect of lifestyle interventions on glucose regulation among adults without impaired glucose tolerance or diabetes: A systematic review and meta-analysis

This study systematically assessed the effectiveness of lifestyle interventions on glycemic indicators among adults (P18 years) without IGT or diabetes. Randomized controlled trials using physical activity (PA), diet (D), or their combined strategies (PA + D) with follow-up P12 months were systematically searched from multiple electronic-databases between inception and May 4, 2016. Outcome measures included fasting plasma glucose (FPG), glycated hemoglobin (HbA1c), fasting insulin (FI), homeostasis model assessment-estimated insulin resistance (HOMA-IR), and bodyweight. Included studies were divided into lowrange (FPG < 5.5 mmol/ L or HbA1c < 5.5%) and high-range (FPG P5.5 mmol/ L or HbA1c P5.5%) groups according to baseline glycemic levels. Seventy-nine studies met inclusion criteria. Random-effect models demonstrated that compared with usual care, lifestyle interventions achieved significant reductions in FPG (-0.14 mmol/ L [ 95% CI, -0.19, -0.10]), HbA1c (-0.06% [-0.09, -0.03]), FI (% change: -15.18% [-20.01, -10.35]), HOMA-IR (% change: - 22.82% [-29.14, -16.51]), and bodyweight (% change: -3.99% [-4.69, -3.29]). The same effect sizes in FPG reduction (0.07) appeared among both low-range and high-range groups. Similar effects were observed among all groups regardless of lengths of follow-up. D and PA + D interventions had larger effects on glucose reduction than PA alone. Lifestyle inter-ventions significantly improved FPG, HbA1c, FI, HOMA-IR, and bodyweight among adults without IGT or diabetes, and might reduce progression of hyperglycemia to type 2 diabetes mellitus.