Association Study of Fasting Blood Glucose and Salt Sensitivity of Blood Pressure in Community Population: The EpiSS Study

Background: Some populations showed heterogeneous elevated blood pressure (BP) responses to relatively high salt intake, which is the phenomenon generally referred as salt sensitivity of blood pressure (SSBP). We aimed to evaluate whether the fasting blood glucose (FBG) could be an independent risk factor, and dose-dependent associated with the SSBP in community population. Methods: This study is based on the baseline survey of systemic epidemiology of salt sensitivity study. Subjects were classified into salt sensitive (SS) and salt resistant (SR) groups according to BP changes during the modified Sullivan’s acute oral saline load (ΔBP 1 ) and diuresis shrinkage (ΔBP 2 ) test. Multivariate logistic regression and multivariate linear regression were used to evaluate associations between FBG with SS or BP changes. Results: A total of 2051 participants were included in the analyses with 581 (28.33%) for SS. The median level of FBG and frequency of diabetes were significantly higher in SS group than those in SR group (5.55 vs. 5.39 mmol/L, P =0.003; 19.62% vs. 14.49%, P =0.005). Multiple logistic analyses showed a positive association between FBG and SS prevalence, for every interquartile range increase in FBG, the OR ( 95%CI ) for SS was 1.140 (1.069, 1.215). Consistently, multivariate linear regression analyses showed that FBG was independently and positively associated with mean arterial pressure change (ΔMAP 1 ) ( β =0.421; 95%CI , 0.221, 0.622), systolic BP change ( β =0.589; 95%CI , 0.263, 0.914) and diastolic BP change ( β =0.340; 95%CI , 0.149, 0.531) during saline load, respectively. Compared to the lowest FBG quartile (Q 1 ), the OR ( 95%CI ) for SS in Q 3 and Q 4 were 1.342 (1.014, 1.776) and 1.577 (1.194, 2.084), respectively ( P for trend ≤ 0.001). Compared to subjects with normal fasting glucose, the β ( 95%CI ) for ΔMAP 1 was 0.973 (0.055, 1.891) in subjects with impaired fasting glucose, and was 1.449 (0.602, 2.296) in patients with diabetes ( P for trend ≤ 0.001). Stratified analyses showed significant and stronger associations between FBG with SSBP in youngers, females, hypertensives, non-diabetics, non-current smokers and non-current drinkers. Conclusions: Our findings suggest FBG is an independent, dose-dependent risk factor for SSBP, and prevention of SS focusing on controlling FBG elevation in the early stage is important.