Coffee is among the most commonly consumed beverages in The Netherlands. Caffeine can acutely lower insulin sensitivity, but it is not clear whether tolerance for this effect develops after long-term regular intake. Furthermore, it is plausible that the effects of coffee are different from those of caffeine. Coffee contains hundreds of substances and there are indications that certain components may partly counter-act the effect of caffeine or may have independent beneficial effects. Intake of the coffee components chlorogenic acid, quinides, lignans, and trigonelline improved glucose metabolism in animal studies. Habitual coffee consumption has been studied in relation to the risk of diabetes mellitus type 2 in 12 cohort studies in Europe, the USA, and Japan. Generally, high coffee consumption was associated with a substantially lower risk of type-2 diabetes. The findings were similar for caffeinated and decaffeinated coffee, suggesting that the non-caffeine components of coffee may be responsible. Identification of these coffee components may lead to the development or selection of coffee types with improved effects on health.