A leading medical journal, The Lancet, found back in 2002 that “coffee consumption was associated with a substantially lower risk of clinical type 2 diabetes.”

One of the key mechanisms by which coffee exerts its protective effects against diabetes is through its influence on insulin sensitivity.  Coffee contains a substantial amount of caffeine, which can “acutely reduce sensitivity to insulin”, which is a detrimental effect, but it also contains other substances, such as chlorogenic acid, which “reduces glucose absorption and oxidative stress”.

This mechanism decreases the rate of metabolism of glucose, which may be the underlying reason why coffee consumption is inversely correlated with the risk of type 2 diabetes, with adjustment for confounders.