Drinking 12 or more cups of coffee daily was associated with a significant reduction in the incidence of type 2 diabetes over nearly 8 years, compared with consuming no coffee, according to the findings of a study published online.
The study looked at self-reported coffee intake among men and women aged 45-74 years who had participated in the 4,579-person Strong Heart Study, an investigation of cardiovascular disease among 13 American Indian tribes/communities. Participants in that study had baseline data collected during 1989-1992 and were followed for an average of 7.6 years.
Participants in the current analysis were the 1,141 men and women who had normal fasting glucose at baseline, wrote Dr. Ying Zhang of the Oklahoma University Health Sciences Center, Oklahoma City, and associates (Nutr. Metab. Cardiovasc. Dis. 2010 Feb. 18 [doi: 10.1016/j.numecd.2009.10.020
The 92 (8.1%) participants who reported drinking at least 12 cups of coffee daily had a 67% lower risk (hazard ratio, 0.33) of developing type 2 diabetes during the follow-up period than non–coffee drinkers, even after adjustment for age, gender, smoking, alcohol use, family history of diabetes, physical activity, and body mass index.
In fact, coffee consumption was significantly related to diabetes risk only among those people who drank 12 or more cups daily, they noted.
Hazard ratios for developing diabetes were 0.93, 0.87, 0.72, and 0.78 for those with daily intake of 1-2 cups, 3-4 cups, 5-7 cups, and 8-11 cups, respectively, the investigators found.
The findings support those from several other studies showing a link between caffeine intake and diabetes development, but this is one of the few investigations that focused on a population known to have a high incidence of diabetes and that had normal glucose tolerance at baseline.
Additional studies are needed on the various elements in coffee, such as antioxidants, phenol chlorogenic acid, magnesium, and caffeine, that may be involved in the biologic mechanisms linking coffee consumption and diabetes risk reduction, they said.
The investigation was limited by a lack of available dietary data on the participants. High coffee consumption may be a marker for dietary patterns and factors related to diabetes risk but not measured in this study, Dr. Zhang and associates noted.
Further study is needed to determine if the association between coffee consumption and diabetes development found in this study is causal or the result of such unmeasured confounders. Also, the potential benefits of consuming 12 or more cups of coffee daily should be weighed against potential detrimental effects on blood pressure levels and sleep patterns, the investigators said.
The study was supported by grants from the National Heart, Lung, and Blood Institute.
Coffee consumption was significantly related to diabetes risk only among those people who drank 12 or more cups daily.
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