The effects of Mediterranean diet on cardiovascular risk factors, glycemic control and weight loss in patients with type 2 diabetes: A meta- analysis

Abstract To explore the impact of the Mediterranean diet on cardiovascular risk factors, glycemic control and weight loss in patients with type 2 diabetes(T2D) by a meta-analysis of randomized controlled trials (RCTs). We systematically searched PubMed, Cochrance Library, EMBASE and four Chinese databases to identify RCTs that compared the Mediterranean diet with control diets in patients with T2D up to December 2021. The Risk of Bias of the included studies was assessed using the version 2 of the Cochrane risk-of-bias tools for randomized trials (ROB 2). Seven RCTs with 1371 patients met the eligibility criteria and entered into the meta-analysis. Compared to control diets, the beneficial effects of Mediterranean diet were not statistically significant in high-density lipoprotein (MD = 2.33; 95% CI: -0.27 to 4.92), low-density lipoprotein (MD -2.34; 95% CI -5.67 to 0.99) and total cholesterol (MD = 2.92; 95% CI: -0.84 to 6.67). But Mediterranean diet led to reduce the level of systolic blood pressure (MD = -1.20; 95% CI: -2.21 to -0.19) and diastolic blood pressure (MD = -4.17; 95% CI: -7.12 to -1.22). Meanwhile, Mediterranean diet showed beneficial effects in glycemic control (HbA1[%]:MD = -0.39, 95% CI: -0.58 to -0.20; fasting plasma glucose: MD = -15.12 mg/dl, 95% CI: -24.69 to -5.55mg/dl) and weight loss (BMI: MD = -0.71, 95% CI: -1.30 to -0.78; MD = -1.69; 95% CI: -3.35 to -0.02) compared to the control diets. The meta-analysis provided evidence the Mediterranean diet showed the beneficial improvements in blood pressure glycemic control and weight loss, but the effect of Mediterranean diet on lipid profile was not significant, which needed further verification.