A researcher who studies coffee said the new study has some limitations. For one, it looks at effects over one day, rather than over the long term, said Rob van Dam, a research scientist at Harvard School of Public Health. For another, "it should be noted that effects of caffeine in capsules cannot be directly translated to effects of caffeinated coffee, as studies have previously found less pronounced effects of caffeinated coffee on blood glucose levels as compared with caffeine in isolation," he added.
What to do? Keep coffee consumption under control, Lane suggested. "It would be worthwhile for people with diabetes who drink coffee to try quitting for a time and see if their glucose improves," Lane said. "It's a simple thing that might make their diabetes better."
Decaf may also do the trick. Indeed, van Dam said a previous study showed decaffeinated coffee actually reduced spikes in glucose levels after people ate sugary food. "It may thus be useful for persons with diabetes to try switching from caffeinated to decaffeinated coffee and see whether this improves their glycemic control, he said.
Learn more about diabetes from the National Institutes of Health.
SOURCES: James Lane, Ph.D., professor, medical psychology, Duke University, Durham, N.C.; and Rob van Dam, Ph.D., research scientist, Harvard School of Public Health, Boston; February 2008, Diabetes Care
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