US Pharm. 2008;33(7):HS-16. 

Researchers at Duke University have discovered that caffeine taken in even moderate doses could impair glucose control in patients with type 2 diabetes. According to James D. Lane, PhD, of Duke University, a small study showed that when patients with type 2 diabetes drank the equivalent of four cups of coffee a day, their blood glucose levels were 8% higher on average. His results were published in Diabetes Care.

Dr. Lane suggests that  patients with type 2 diabetes cut coffee out of their diet to see if this better controls their blood sugar levels. "Caffeine is so widely consumed in our society that we tend to forget or ignore the fact that it is a drug that does have widespread effects in the body," said Dr. Lane.

Dr. Lane and his colleagues hypothesize that the caffeine may affect blood glucose in patients with type 2 diabetes in two ways. The first theory is that caffeine impairs the transport of glucose out of the bloodstream and into the cell. A second theory is that, because it promotes the release of adrenaline, caffeine stimulates the liver to continue to release glucose even after a meal.

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