Dietary Salt Intake and Mortality in Patients With Type 2 Diabetes

  1. George Jerums, MD1
  1. 1Endocrine Centre, Heidelberg Repatriation Hospital, Austin Health and the University of Melbourne, Victoria, Australia
  2. 2Mater Hospital, Queensland, Australia
  3. 3Division of Diabetes Complications, Baker IDI Heart and Diabetes Institute, Central Victoria, Australia
  4. 4Department of Intensive Care Medicine, The Queen Elizabeth Hospital & Health Service, Woodville, South Australia
  1. Corresponding author: George Jerums, ah-endo{at}unimelb.edu.au.

Abstract

OBJECTIVE Many guidelines recommend that patients with type 2 diabetes should aim to reduce their intake of salt. However, the precise relationship between dietary salt intake and mortality in patients with type 2 diabetes has not been previously explored.

RESEARCH DESIGN AND METHODS Six hundred and thirty-eight patients attending a single diabetes clinic were followed in a prospective cohort study. Baseline sodium excretion was estimated from 24-h urinary collections (24hUNa). The predictors of all-cause and cardiovascular mortality were determined by Cox regression and competing risk modeling, respectively.

RESULTS The mean baseline 24hUNa was 184 ± 73 mmol/24 h, which remained consistent throughout the follow-up (intraindividual coefficient of variation [CV] 23 ± 11%). Over a median of 9.9 years, there were 175 deaths, 75 (43%) of which were secondary to cardiovascular events. All-cause mortality was inversely associated with 24hUNa, after adjusting for other baseline risk factors (P < 0.001). For every 100 mmol rise in 24hUNa, all-cause mortality was 28% lower (95% CI 6–45%, P = 0.02). After adjusting for the competing risk of noncardiovascular death and other predictors, 24hUNa was also significantly associated with cardiovascular mortality (sub-hazard ratio 0.65 [95% CI 0.44–0.95]; P = 0.03).

CONCLUSIONS In patients with type 2 diabetes, lower 24-h urinary sodium excretion was paradoxically associated with increased all-cause and cardiovascular mortality. Interventional studies are necessary to determine if dietary salt has a causative role in determining adverse outcomes in patients with type 2 diabetes and the appropriateness of guidelines advocating salt restriction in this setting.

  • Received September 6, 2010.
  • Accepted December 30, 2010.

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  1. Diabetes Care
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