|October 25, 2006 — Coffee consumption reduces the risk for type 2 diabetes by 60% compared with those who do not drink coffee, according to the results of a large prospective study reported in the November issue of Diabetes Care.|
"Several recently published cohort studies suggest a significant reduced risk of type 2 diabetes in coffee drinkers," write Besa Smith, MPH, from the University of California San Diego in La Jolla, and colleagues. "The purpose of this study was to investigate the association between coffee intake and incident diabetes based on an oral glucose tolerance test (OGTT) and examine coffee habits in those with impaired glucose separately from those with normal glucose at baseline."
From 1984-1987 until 1992-1996, the investigators followed up 910 adults aged 50 years or older without diabetes at baseline. Average follow-up was 8 years after assessment of coffee intake. Logistic regression models were adjusted for sex, age, physical activity, body mass index, smoking, alcohol, hypertension, and baseline fasting plasma glucose.
Compared with those who never drank coffee, past and current coffee drinkers had a lower risk for incident diabetes (odds ratio [OR], 0.38; 95% confidence interval [CI], 0.17 - 0.87; and OR, 0.36; 95% CI, 0.19 - 0.68, respectively). The 317 participants who had impaired glucose at baseline and who were past or current coffee drinkers also had reduced risk for incident diabetes (OR, 0.31; 95% CI, 0.11 - 0.87; and OR, 0.36; 95% CI, 0.16 - 0.83, respectively).
"This study confirms a striking protective effect of caffeinated coffee against incident diabetes and extends these findings to incident diabetes based on OGTT independent of multiple plausible confounders," the authors write. "The quantity of coffee consumed daily (cup-years) did not predict diabetes risk in either those with normal or impaired glucose at baseline."
Study limitations include a predominantly middle-class, white population limiting generalizability; possible survival bias; and self-reported coffee consumption subject to recall bias.
"Given the increasing prevalence of obesity, IGT [impaired glucose tolerance], and diabetes, and the fact that the majority of adults in most of the Westernized world drink coffee daily, a coffee benefit could have widespread impact," the authors conclude. "Further investigation is warranted."
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