Coffee, decaffeinated coffee, and tea consumption in relation to incident type 2 diabetes mellitus: a systematic review with meta-analysis.

betes, respectively. We found an inverse log-linear rela- tionshipbetweencoffeeconsumptionandsubsequentrisk of diabetes such that every additional cup of coffee con- sumed in a day was associated with a 7% reduction in the excess risk of diabetes relative risk, 0.93 (95% con- fidence interval, 0.91-0.95)) after adjustment for poten- tial confounders. Conclusions:Owingtothepresenceofsmall-studybias, ourresultsmayrepresentanoverestimateofthetruemag- nitude of the association. Similar significant and inverse associationswereobservedwithdecaffeinatedcoffeeand tea and risk of incident diabetes. High intakes of coffee, decaffeinated coffee, and tea are associated with re- duced risk of diabetes. The putative protective effects of thesebeverageswarrantfurtherinvestigationinrandom- ized trials.