Coffee and Tea Consumption and Risk of Type 2 Diabetes in Older Australians

Background: The prospective relationship between coffee and tea consumption and the risk of developing type 2 diabetes mellitus (T2DM) is seldom assessed in older adults. This study investigated the association between coffee and tea consumption and the 10-year incidence of T2DM in older Australian adults. Method: Data were collected from participants aged 49 years or above at baseline of the Blue Mountains Eye Study (n = 1668). Coffee and tea intakes were assessed using a validated food frequency questionnaire. T2DM was ascertained by the self-reported history, fasting blood glucose ≥ 7.0 mmol/L, or self-reported use of diabetes medication. Associations were assessed using discrete-time logistic regression, adjusting for lifestyle and demographic factors. Results: Compared to no consumption, coffee intake of 1 cup/day was associated with a lower risk of developing T2DM (multivariate-adjusted HR: 0.46, 95% CI: 0.23, 0.91) in the 10-year follow-up period. However, consumption of 2–3 cups/day (HR: 0.66, 95% CI: 0.37, 1.18) or ≥4 cups/day (HR: 1.04, 95% CI: 0.52, 2.08) showed no significant association. Tea consumption at any level was not significantly associated with T2DM incidence. Results were similar after excluding participants with implausible energy intake. Conclusions: In older adults, moderate coffee intake (1 cup/day) was associated with lower T2DM incidence, while higher coffee consumption and tea intake at any level were not. The lack of a dose-dependent effect in coffee consumption warrants further investigation. These findings should be verified in larger studies, considering different coffee and tea types and potential age-related and genetic factors.