October 29, 2010 — Serum potassium level is an independent predictor of incident type 2 diabetes mellitus, according to results from the Atherosclerosis Risk in Communities (ARIC) Study reported in the October 25 issue of the Archives of Internal Medicine.
"Serum potassium levels affect insulin secretion by pancreatic β-cells, and hypokalemia associated with diuretic use has been associated with dysglycemia," write Ranee Chatterjee, MD, MPH, from the Johns Hopkins University in Baltimore, Maryland, and colleagues. "We hypothesized that adults with lower serum potassium levels and lower dietary potassium intake are at higher risk for incident diabetes mellitus (DM), independent of diuretic use."
ARIC is an ongoing, prospective cohort study initiated in 1986. The investigators analyzed data from 12,209 participants enrolled in ARIC who had 9 years of in-person follow-up and 17 years of telephone follow-up. The hazard ratio (HR) of incident diabetes mellitus associated with baseline serum potassium levels was estimated with use of multivariate Cox proportional hazard models,
Incident diabetes mellitus developed in 1475 participants during 9 years of in-person follow-up. Serum potassium level was inversely associated with the risk for incident diabetes, based on multivariate analyses. Compared with adults who had a high-normal serum potassium level (5.0 - 5.5 mEq/L), those with serum potassium levels less than 4.0 mEq/L, 4.0 to less than 4.5 mEq/L, and 4.5 to less than 5.0 mEq/L had an adjusted HR of incident diabetes of 1.64 (95% confidence interval [CI], 1.29 - 2.08), 1.64 (95% CI, 1.34 - 2.01), and 1.39 (95% CI, 1.14 - 1.71), respectively.
During an additional 8 years of telephone follow-up, those with a serum potassium level of less than 5.0 mEq/L had a persistently increased risk for self-reported diabetes mellitus, with HRs of 1.2 to 1.3. In unadjusted models but not in multivariate models, dietary potassium intake was significantly associated with the risk for incident diabetes.
"Serum potassium level is an independent predictor of incident DM in this cohort," the study authors write. "Further study is needed to determine if modification of serum potassium could reduce the subsequent risk of DM."
Limitations of this study include single measurement of serum potassium level at baseline visit, use of an unreliable measure of fasting insulin level, different methods of diabetes ascertainment for the in-person visit data and the telephone follow-up data, and observational design unable to prove causality.
"The association between increased risk of DM and low serum potassium levels seen in this cohort should be assessed in other populations," the study authors conclude. "Finally, clinical trials should be developed to assess if increasing serum potassium, through medications, pharmacologic supplementation, or increased dietary intake — all relatively simple interventions — could indeed reduce the risk of incident DM."
The National Heart, Lung, and Blood Institute, the National Institute of Diabetes, Digestive, and Kidney Diseases (NIDDK), the National Institutes of Health, and the NIDDK Diabetes Research and Training Center funded this study. The study authors have disclosed no relevant financial relationships.
Arch Intern Med. 2010;170:1745-1751. Abstract
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