Association between Coffee Consumption and Renal Impairment in Korean Women with and without Diabetes: Analysis of the Fourth Korea National Health and Nutrition Examination Survey in 2008

BACKGROUND Recent studies suggest that coffee consumption has an influence on kidney function. This study investigated the relationship between habitual coffee consumption and renal impairment in Korean women, in consideration of diabetic status. METHODS This study involved 2,673 women aged 35 to 84 years who had participated in the Fourth Korea National Health and Nutrition Examination Surveys, conducted in 2008. Habitual coffee consumption was classified into three categories: less than 1 cup per day, 1 cup per day, and 2 or more cups per day. Renal function impairment was defined as an estimated glomerular filtration rate less than 60 mL/min/1.73 m(2) by the Modification of Diet in Renal Disease equation. RESULTS The prevalence of diabetes and renal function impairment was higher in women who drank < 1 cup of coffee per day. Compared with drinking < 1 cup of coffee per day, the odds ratio (OR) for renal function impairment was significantly lower (OR, 0.59; 95% confidence interval [CI], 0.37 to 0.95; P = 0.03) in those who habitually drank ≥ 2 cups per day after adjusting for multiple confounding factors. When data were stratified according to the presence of diabetes, coffee consumption ≥ 2 cups of coffee per day showed an inverse association with renal function impairment in only diabetic women (OR, 0.14; 95% CI, 0.02 to 0.88; P = 0.04), compared with consumption < 1 cup of coffee per day. CONCLUSION In a representative sample of Korean women, coffee consumption was significantly associated with a decreased risk of renal impairment especially in middle and elderly-aged diabetic women.