High coffee consumption could be associated with a reduced risk of type 2 diabetes, suggest Dutch researchers in a letter in this week's issue of The Lancet.
While caffeine is known to reduce sensitivity to insulin (the hormone responsible for the metabolism of glucose), other components of coffee such as magnesium and chlorogenic acid could offer some health benefits they write.
Rob van Dam and colleagues from the Dutch national Institute for Public Health and the Environment in Bilthoven, Netherlands, assessed the effect of varying coffee consumption on the development of Type 2 diabetes in around 17,000 Dutch adults.
They report that individuals with high coffee consumption - those who drank seven or more cups of coffee a day - were 50 per cent less likely to develop Type 2 diabetes compared with less frequent coffee drinkers (two cups a day or less), even when confounding factors such as smoking, alcohol consumption and body mass were taken into account.
Rob van Dam commented: "Caffeine acutely lowers insulin sensitivity, but long-term effects are unknown. In an intervention study, increased coffee consumption for 14 days reduced fasting plasma glucose, whereas substitution of regular coffee for decaffeinated coffee for 20 days did not affect plasma glucose. That study did not include a control group, but the results suggested that components of coffee other than caffeine could be beneficial for glucose metabolism."
He continued: "In view of the widespread use of coffee and the large health burden of Type 2 diabetes, our finding of an inverse association between coffee consumption and risk of Type 2 diabetes could have important public-health implications."
He added that further studies were needed to assess possible adverse effects on other health aspects before coffee could be strongly advocated.