The impact of major dietary patterns on glycemic control, cardiovascular risk factors, and weight loss in patients with type 2 diabetes: A network meta‐analysis

OBJECTIVE: To comprehensively compare the differences between major dietary patterns in improving glycemic control, cardiovascular risk, and weight loss for patients with type 2 diabetes. METHOD: We systematically searched PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) to identify randomized controlled trials (RCTs) that compared the efficacy of Mediterranean, low-carbohydrate, and/or low-fat dietary patterns for patients with type 2 diabetes. Studies that compared any one of those diets with regular diet were also included. The risk of bias in eligible RCTs was evaluated according to the Cochrane Handbook. The primary outcome was glycemic control. Secondary outcomes included weight loss and cardiovascular risk factors. A network meta-analysis was performed using R-3.3.2. RESULTS: Ten RCTs involving five dietary patterns met the eligibility criteria. The findings revealed that compared to low-fat diet, Mediterranean diet showed beneficial effects in glycemic control (HbA1c [%]: MD = -0.45, 95% CI = -0.55 to -0.34; fasting plasma glucose [mmol/L]: MD = -1.24 95% CI = -1.57 to -0.91, respectively; weight loss [kg]: MD =-1.18, 95% CI = -1.99 to -0.37; waist circumference [cm]: MD = -0.73, 95% CI = -1.26 to -0.19), and cardiovascular risk factors (HDL-cholesterol [mmol/L]: MD = 0.07, 95% CI = 0.04 to 0.11; total cholesterol [mmol/L]: MD = -0.17, 95% CI = -0.26 to -0.08; triglycerides [mmol/L]: MD = -0.21, 95% CI = -0.27 to -0.16). Network meta-analysis showed that high-carbohydrate diet improved HDL-cholesterol (mmol/l) (MD = 1.04, 95% CI = 0.39 to 1.68) when compared with regular diet. The differences were not statistically significant in other indirect comparison groups for other outcomes. CONCLUSIONS: A mediterranean diet showed beneficial improvements in glycemic control, weight loss, and cardiovascular risk factors in people with type 2 diabetes.