Multiple 24-Hour Urinary Sodium and Potassium Excretions and Type 2 Diabetes Incidence

High sodium and low potassium intake, well-established dietary risk factors for hypertension, may induce insulin resistance and increase the risk of type 2 diabetes. However, previous research based on self-reported intakes is inconclusive. We examined the association of sodium and potassium intake, assessed by multiple 24-h urine samples, with subsequent risk of developing type 2 diabetes.

We included 3,173 adults without major chronic diseases from three prospective cohorts. Sodium and potassium excretions were assessed using two to four 24-h urine collections per participant. We used Cox proportional hazards models to estimate hazard ratios (HR) for type 2 diabetes, adjusting for major confounding factors, including total energy intake and BMI.

Among 3,173 participants (mean age 62.2 ± 10.0 years, 69% women), diabetes developed in 161 over a median of 13.6 years. Risk of diabetes was 2.66 (95% CI 1.57-4.51) times higher in participants in the highest versus the lowest quartile of sodium excretion. Each 1,000 mg/day increase in sodium excretion was associated with a 32% (HR 1.32; 95% CI 1.16-1.52) higher risk of diabetes, whereas potassium excretion was not associated with diabetes risk (HR 0.87; 95% CI 0.69-1.11). Each unit increase in the sodium-to-potassium ratio was associated with a 26% higher risk of diabetes (95% CI 1.10-1.45).

Higher sodium intake and a higher sodium-to-potassium ratio were associated with a higher risk of type 2 diabetes. Although these findings suggest that adopting a low-sodium diet may reduce diabetes risk, the associations may partly reflect residual confounding despite comprehensive covariate adjustment.