Effects of dietary salt intake restriction on blood glucose levels: a meta-analysis of crossover study

BACKGROUND/OBJECTIVES: To identify modifiable risk factors for type 2 diabetes mellitus and explore the relationship between diet sodium intake and blood glucose levels. MATERIALS/METHODS: Based on inclusion and exclusion criteria, we extracted, analyzed, and assessed the available crossover studies of dietary salt intake restriction and insulin resistance in PubMed, Web of Science, MEDLINE, Embase, Wanfang, and CNKI databases. RESULTS: We included 6 studies with 8 sets of data, covering 485 subjects. I(2) statistics results showed insignificant heterogeneity among all data (I(2) = 39.2% < 50%). Thus, a fixed-effect model was adopted for the final pooled effect size. Weighted mean difference and its 95% confidence interval (CI) value was 0.193 (95% CI, 0.129–0.257), and the test of the overall effect showed P < 0.001. The results revealed that the blood glucose levels in the subjects in the low-salt intake group were significantly higher than those in the normal or high-salt intake groups. We also found no significant change occurred after the removal of any study through sensitivity analysis, which confirmed that the outcome we calculated was prudent and credible. The quantitative Egger’s test (P = 0.109 > 0.05) indicated that insignificant publication bias existed. CONCLUSION: This meta-analysis highlights the relationship between dietary sodium intake and blood glucose levels. Our findings show that higher blood glucose levels might be expected in hypertensive or normal people with low-salt consumption compared to those with normal or high-salt consumption, although these differences were not clinically significant. TRIAL REGISTRATION: PROSPERO Identifier: CRD42021256998