Association Between Coffee Consumption and Glucose Metabolism Markers in Korean Adults

Background/Objectives: Studies examining the association between coffee consumption and glucose metabolism markers have reported inconsistent findings, and few have considered coffee type. We investigated the association between coffee consumption and glucose metabolism markers in Korean adults. Methods: A cross-sectional analysis was conducted using data from the Korea National Health and Nutrition Examination Survey (2019-2021), including 7453 adults aged 19-64 years. Coffee consumption was assessed using a 24 h dietary recall and categorized as black coffee or coffee with sugar and/or cream (non-drinkers, ≤1 cup/day, 2 cups/day, and ≥3 cups/day). Multivariable logistic regression models were used to assess the associations with glucose metabolism markers, including the homeostasis model assessment of insulin resistance (HOMA-IR). Results: The mean age of participants was 40.6 years (standard error: 0.19). After full adjustment for covariates, in women, consuming two or more cups of black coffee per day was inversely associated with elevated HOMA-IR (2 cups/day: OR = 0.73, 95% CI: 0.56-0.96; ≥3 cups/day: OR = 0.66, 95% CI: 0.44-0.99) and fasting insulin levels (2 cups/day: OR = 0.70, 95% CI: 0.54-0.91; ≥3 cups/day: OR = 0.64, 95% CI: 0.43-0.93), compared to no consumption, showing a significant linear trend (p-trend ≤0.01 for all cases). By coffee type, women who consumed more black coffee had lower odds of elevated HOMA-IR and fasting insulin levels (p-trend ≤0.02). In men or those consuming coffee with sugar and/or cream, no significant associations with glucose metabolism markers were observed. Conclusions: Our findings indicate that consuming two or more cups of black coffee per day is inversely associated with insulin resistance in Korean women.