Serum and dietary potassium and risk of incident type 2 diabetes mellitus: The Atherosclerosis Risk in Communities (ARIC) study

Abstract

Background: Serum potassium levels affect insulin secretion by pancreatic β-cells, and hypokalemia associated with diuretic use has been associated with dysglycemia. 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.

Methods: We analyzed data from 12 209 participants from the Atherosclerosis Risk in Communities (ARIC) Study, an ongoing prospective cohort study, beginning in 1986, with 9 years of in-person follow-up and 17 years of telephone follow-up. Using multivariate Cox proportional hazard models, we estimated the hazard ratio (HR) of incident DM associated with baseline serum potassium levels.

Results: During 9 years of in-person follow-up, 1475 participants developed incident DM. In multivariate analyses, we found an inverse association between serum potassium and risk of incident DM. Compared with those with a high-normal serum potassium level (5.0-5.5 mEq/L), adults with serum potassium levels lower than 4.0 mEq/L, 4.0 to lower than 4.5 mEq/L, and 4.5 to lower than 5.0 mEq/L had an adjusted HR (95% confidence interval [CI]) of incident DM of 1.64 (95% CI, 1.29-2.08), 1.64 (95% CI, 1.34-2.01), and 1.39 (95% CI, 1.14-1.71), respectively. An increased risk persisted during an additional 8 years of telephone follow-up based on self-report with HRs of 1.2 to 1.3 for those with a serum potassium level lower than 5.0 mEq/L. Dietary potassium intake was significantly associated with risk of incident DM in unadjusted models but not in multivariate models.

Conclusions: Serum potassium level is an independent predictor of incident DM in this cohort. Further study is needed to determine if modification of serum potassium could reduce the subsequent risk of DM.

Figure 1

Adjusted relative hazards for incident diabetes by serum potassium at baseline. Relative hazards are adjusted for age, sex, race, center, BMI, waist circumference, serum magnesium, calcium, and creatinine levels, physical activity levels, parental history of diabetes, presence of hypertension, systolic blood pressure (average of 2^nd and 3^rd measurements), fasting glucose, fasting insulin, income, use of beta-blockers, use of diuretics, and use of ACE-I. Bars indicate 95% confidence interval. Results are plotted at the medians of the potassium categories (3.8, 4.2. 4.7, and 5.2 mEq/L).

Figure 2

Adjusted relative hazards of incident diabetes by potassium category for participants on diuretics and not on diuretics. Relative hazards are adjusted for age, sex, race, center, BMI, waist circumference, serum magnesium, calcium, and creatinine levels, physical activity level, parental history of diabetes, presence of hypertension, systolic blood pressure (average of 2^nd and 3^rd measurements), fasting glucose, fasting insulin, income, use of beta-blockers and use of ACE-I. Bars indicate 95% confidence interval. Results are plotted at the medians of the categories (3.8, 4.2. 4.7, and 5.2 mEq/L).