Low daily salt intake is correlated with albuminuria in patients with type 2 diabetes

Both high and low salt intakes have been reported to be associated with an increased risk of cardiovascular events. The aim of this study was to investigate the relationship between daily salt intake and albuminuria, a marker of diabetic nephropathy and cardiovascular disease, in patients with type 2 diabetes. We classified 270 patients with type 2 diabetes, who were not receiving antihypertensive medication into four groups according to their daily salt intake (<8, 8-10, 10-12 and >12 g per day). We investigated the relationship between daily salt intake and the logarithm of urinary albumin excretion (UAE). A multivariate linear regression analysis was used to evaluate whether daily salt intake independently correlated with the logarithm of UAE. In addition, we assessed the contribution of the variables, including age, sex, duration of diabetes, body mass index, systolic blood pressure, hemoglobin A(1C), low-density lipoprotein cholesterol, triglycerides, serum creatinine, alcohol intake, smoking status and square of (daily salt intake-10) on albuminuria, defined as a UAE>30 mg g(-1) of creatinine, using a multiple logistic regression analysis. The logarithm of the UAE was lowest in the third quartile of daily salt intake. The multivariate linear regression analysis demonstrated that the logarithm of the UAE was significantly correlated with the quadratic term of daily salt intake centered at 10 g per day (β=0.170, P=0.008). The multivariate logistic regression analysis demonstrated that the odds ratio (95% confidence interval) of albuminuria was 3.996 (1.295-12.327; P=0.016) in patients whose daily salt intake was less than 8 g per day compared with patients whose daily salt intake was 10-12 g per day. In conclusion, low daily salt intake was correlated with albuminuria in patients with type 2 diabetes, who were not receiving antihypertensive medication.