High coffee, tea intake may reduce chances of developing type 2 diabetes

Moral of the story: Drinking coffee and tea reduces chances of developing type II (late onset) diabetes

Source: AMA Morning Rounds 12/15/09;  Arch Intern Med. 2009;169(22):2053-2063.

High coffee, tea intake may reduce chances of developing type 2 diabetes.

Bloomberg News (12/15, Gibson) reports that, according to a study published in the Archives of Internal Medicine, "drinking four cups of coffee, decaf, or tea daily can reduce the chances of getting type 2 diabetes by about 25 percent to 35 percent." Harvard University "researchers reviewed 18 studies of almost 500,000 people" and discovered that "for each cup of coffee people drank, their likelihood of getting diabetes dropped by seven percent."

        "Even better results were found for bigger coffee and tea consumers -- drinking three to four cups a day was associated with about a 25% reduced diabetes risk, compared with those who drank between none and two cups day," the Los Angeles Times (12/15, Stein) reports. In addition, investigators found "positive results with decaf coffee and tea." Specifically, those "who drank more than three to four cups of decaf a day had about a one-third lower risk than those who didn't drink any," while "tea drinkers who consumed more than three to four cups a day had about a one-fifth lower diabetes risk than non-tea drinkers."

        HealthDay (12/14, Gordon) and MedPage Today (12/14, Fiore) also covered the story.

Coffee, Decaffeinated Coffee, and Tea Consumption in Relation to Incident Type 2 Diabetes Mellitus
A Systematic Review With Meta-analysis
Rachel Huxley, DPhil; Crystal Man Ying Lee, PhD; Federica Barzi, PhD; Leif Timmermeister; Sebastien Czernichow, MD, PhD; Vlado Perkovic, MD, PhD; Diederick E. Grobbee, MD, PhD; David Batty, PhD; Mark Woodward, PhD



Background  Coffee consumption has been reported to be inversely associated with risk of type 2 diabetes mellitus. Similar associations have also been reported for decaffeinated coffee and tea. We report herein the findings of meta-analyses for the association between coffee, decaffeinated coffee, and tea consumption with risk of diabetes.
Methods  Relevant studies were identified through search engines using a combined text word and MeSH (Medical Subject Headings) search strategy. Prospective studies that reported an estimate of the association between coffee, decaffeinated coffee, or tea with incident diabetes between 1966 and July 2009.
Results  Data from 18 studies with information on 457 922 participants reported on the association between coffee consumption and diabetes. Six (N = 225 516) and 7 studies (N = 286 701) also reported estimates of the association between decaffeinated coffee and tea with diabetes, respectively. We found an inverse log-linear relationship between coffee consumption and subsequent risk of diabetes such that every additional cup of coffee consumed in a day was associated with a 7% reduction in the excess risk of diabetes relative risk, 0.93 [95% confidence interval, 0.91-0.95]) after adjustment for potential confounders.
Conclusions  Owing to the presence of small-study bias, our results may represent an overestimate of the true magnitude of the association. Similar significant and inverse associations were observed with decaffeinated coffee and tea and risk of incident diabetes. High intakes of coffee, decaffeinated coffee, and tea are associated with reduced risk of diabetes. The putative protective effects of these beverages warrant further investigation in randomized trials.

Author Affiliations: The George Institute for International Health, The University of Sydney, Sydney, Australia (Drs Huxley, Lee, Barzi, Czernichow, Perkovic, Batty, and Woodward and Mr Timmermeister); Department of Public Health, Avicenne Hospital, University of Paris 13, Paris, France (Dr Czernichow); The Julius Center for Health Sciences and Primary Care, Utrecht University Medical Center, Utrecht, the Netherlands (Dr Grobbee); Medical Research Council Social & Public Health Sciences Unit, University of Glasgow, Glasgow, Scotland (Dr Batty); and Mount Sinai School of Medicine, New York, New York (Dr Woodward).