Effects of Mediterranean-style diet on glycemic control, weight loss and cardiovascular risk factors among type 2 diabetes individuals: a meta-analysis

BACKGROUND/OBJECTIVES: Studies suggest that the Mediterranean-style diet (MSD) may improve glucose metabolism in patients with type 2 diabetes (T2D), but the results are inconsistent. We conducted a meta-analysis of randomized controlled trials (RCTs) to explore the effects of MSD on glycemic control, weight loss and cardiovascular risk factors in T2D patients. SUBJECTS/METHODS: We performed searches of EMBASE, Cochrane Library and PubMed databases up to February 2014. We included RCTs that compared the MSD with control diets in patients with T2D. Effect size was estimated as mean difference with 95% confidence interval (CI) by using random effect models. RESULTS: The meta-analysis included nine studies with 1178 patients. Compared with control diets, MSD led to greater reductions in hemoglobin A1c (mean difference, -0.30; 95% CI, -0.46 to -0.14), fasting plasma glucose (-0.72 mmol/l; CI, -1.24 to -0.21), fasting insulin (-0.55 mu U/ml; CI, -0.81 to -0.29), body mass index (-0.29 kg/m(2); CI, -0.46 to -0.12) and body weight (-0.29 kg; CI, -0.55 to -0.04). Likewise, concentrations of total cholesterol and triglyceride were decreased (-0.14 mmol/l; CI, -0.19 to -0.09 and -0.29 mmol/l; CI, -0.47 to -0.10, respectively), and high-density lipoprotein was increased (0.06 mmol/l; CI, 0.02 to 0.10). In addition, MSD was associated with a decline of 1.45 mm Hg (CI, -1.97 to -0.94) for systolic blood pressure and 1.41 mm Hg (CI, -1.84 to -0.97) for diastolic blood pressure. CONCLUSIONS: The present meta-analysis provides evidence that MSD improves outcomes of glycemic control, body weight and cardiovascular risk factors in T2D patients.