The effect of a low versus high sodium diet on blood pressure in diabetic patients: A systematic review and meta-analysis of clinical trials

There have been numerous clinical trials that have investigated the effect of sodium intake on blood pressure in diabetic patients. The purpose of this systematic review and meta-analysis was to evaluate the clinical trial studies performed on the effect of low sodium diet (LSD) versus high sodium diet (HSD) on blood pressure in diabetic patients. PubMed, Scopus, and Web of Science were systematically searched from database inception to July 10, 2021. Both type 1 and 2 diabetes was considered. Overall, there were 15 studies included in this meta-analysis. The weighted (WMD) mean difference with 95% confidence interval (CI) was calculated using a random-effects model. Risk of bias in the studies was assessed based on the Cochrane collaboration tool and the quality of all the studies was considered as good. Overall, LSD significantly reduced SBP (systolic blood pressure) (WMD: -3.79 mmHg, 95% CI: -6.02, -1.56) and DBP (diastolic blood pressure) (WMD: -1.62 mmHg, 95% CI: -2.84, -0.40), in comparison with HSD, in diabetics. However, LSD had no significant effect on MAP (mean arterial pressure) in comparison with HSD (WMD: -1.81, 95%CI: -5.49, 1.87). Although subgroup analysis could not attenuate heterogeneity in SBP, subgroup analysis in DBP based on duration (<= 1 week: WMD: -2.35, 95%CI: -3.69, -1.00, I-2 = 48.9%, p = 0.081, >1 week: WMD: -1.04, 95% CI: -2.83, 0.76, I-2 = 74.7%, p = 0.003) and study design (cross-over: WMD: -1.94, 95% CI: -2.71, -1.17, I-2 = 32.1%, p = 0.183, parallel: WMD: -2.17, 95% CI: -6.48, 2.13, I-2 = 82.4%, p = 0.001) successfully detected sources of heterogeneity. LSD significantly reduced SBP and DBP, however, had no effect on MAP, in comparison with HSD.