In observational studies, habitual coffee consumption has been linked to a lower risk of type 2 diabetes. We hypothesized that the mechanism may be related to delayed effects on postprandial glycemia. The aim of this study is to investigate the glycemic and insulinemic effects of consumption of caffeinated and decaffeinated coffee, sweetened and unsweetened, tea and sucrose, 1 h prior to a high carbohydrate meal. On separate occasions in random order, lean young healthy subjects (n = 8) consumed a potato-based meal 1 hour after consumption of 250 mL of black coffee (COF), black coffee sweetened with 10 g of sucrose (COF+SUC), decaffeinated coffee (DECAF), black tea (TEA), 10 g sucrose (SUC) or hot water (CON). Fingerprick blood samples were taken at regular intervals over 2 h and the glucose and insulin responses quantified as area under the curve. Compared to CON, COF caused a 28% increase in postprandial glycemia (p = 0.022). In contrast, COF+SUC decreased glycemia compared with either COF (-38%, p