Caffeine Increases Blood Sugar in Type 2 Diabetes


Is it time to kick the caffeine habit?

It looks that way if you have type 2 diabetes. According to a recently published study, people with type 2 diabetes who drink the equivalent of four cups of coffee or more a day may experience an 8 percent rise (vs. non-caffeine days) in blood glucose levels.

Java junkies

Dr James Lane, a psychologist at Duke University Medical Center, in Durham, North Carolina, and colleagues, conducted the study which is published in the February issue of Diabetes Care. Lane notes that coffee is “such a common drink in our society that we forget that it contains a very powerful drug: caffeine.”

Caffeine: the drug test

To see the effects of caffeine on blood sugar, patients included in the study could not be on insulin; rather, people were chosen only if they were trying to manage their type 2 diabetes through a healthy eating lifestyle, exercise, and other medications. In the double-blind study, subjects were given caffeine capsules equal to 4 cups of coffee alternating every other day with a placebo. All consumed a nutritional breakfast drink, but were on their own for lunch and dinner.

The results demonstrated the patients’ average daily blood glucose levels went up by 8 per cent on the caffeine days. After meals the blood sugar levels jumped even higher: 9 per cent after breakfast, 15 per cent after lunch, and 26 per cent after dinner.

How does caffeine cause this rise in blood sugar?

“It could be that caffeine interferes with the process that moves glucose from the blood and into muscle and other cells in the body where it is used for fuel. It may also be that caffeine triggers the release of adrenaline — the fight or flight — hormone that we know can also boost sugar levels,” said Lane.

A new prescription for diabetics: healthy eating and healthy drinking

Future research may decisively confirm that managing blood sugar is easier in patients with type 2 diabetes who give up caffeine. In the meantime, doctors may prescribe the elimination of caffeine for good measure.

“It’s not easy,” Lane acknowledges, “but it doesn’t cost a dime, and there are no side effects.”

“Caffeine Increases Ambulatory Glucose and Postprandial Responses in Coffee Drinkers With Type 2 Diabetes.” James D. Lane, Mark N. Feinglos, and Richard S. Surwit. Diabetes Care 31: 221-222.

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