CaffeineCoffeeDiabetes Mellitus

Clarifying the effects of caffeine on insulin and diabetes

Here’s the latest information from 2 studies from Dartmouth University in New Hampshire and Duke University in Durham, North Carolina.

The Dartmouth researchers evaluated the effect of 200 mg of caffeine taken twice a day for 7 days on glucose metabolism in 16 healthy volunteers.

  • Daily caffeine intake reduced insulin sensitivity.
  • The effect persists for at least a week and became evident within 12 hours.

At Duke, researchers compared the effects of a moderate dose of caffeine (500 mg/day) vs placebo. The study group included 10 habitual coffee drinkers. All had at least a 6-month history of type 2 diabetes treated with diet, exercise, and medicine, but no insulin.

  • Caffeine increased their sugar levels 8%.
  • Caffeine also inflated the rise in glucose after meals by 9% after breakfast, 15% after lunch and 26% after dinner.

The bottom line?
Dr. James Lane, the lead author of the second study says, “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.”

Avoiding caffeine improves the actions of insulin and improves diabetes control.

2/3/08 10:44 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.