Effect of Different Dietary Approaches in Comparison with High/Low-Carbohydrate Diets on Systolic and Diastolic Blood Pressure in Type 2 Diabetic Patients: A Systematic Review and Meta-Analysis

Dietary modification is an effective method for preventing and managing hypertension. Therefore, we conducted a systematic review and meta-analysis to assess the effects of different dietary approaches for comparing high- and low-carbohydrate diets on systolic and diastolic blood pressure (SBP and DBP, respectively) in patients with type 2 diabetes mellitus (T2DM). We carried out a comprehensive literature search using PubMed, the Cochrane Library, Web of Science, and Scopus without any language and time restrictions until April, 2019. We carried out a meta-analysis using both fixed and random effects models where appropriate and used the I(2) index to evaluate heterogeneity. We identified 16 eligible studies, with a total of 1,610 participants. The overall pooled net effect of different dietary approaches on SBP and DBP were −2.29 mmHg [95% confidence interval (CI): −3.49 to −1.1] and −1.03 mmHg (95% CI: −1.77 to −0.29), respectively, compared with high-carbohydrate diets. Indeed, diets high in monounsaturated fatty acids more effective in reducing both SBP and DBP than high-carbohydrate diets, whereas high-protein diets were not effective. Furthermore, we found that different dietary approaches, such as low-fat diets, did not reduce SBP or DBP to a greater extent than low-carbohydrate diets. Overall, the results of our meta-analysis show that diets high in monounsaturated fatty acids are more effective in reducing both SBP and DBP than diets high in carbohydrate, whereas other dietary approaches were not effective.