Coffee bad for diabetics, study suggests

Drinking coffee appears to hamper efforts by people with type 2 diabetes to control their blood sugar levels, and can exaggerate the blood sugar rise which occurs after each meal, according to new research.

By continuously monitoring the blood sugar levels of 10 patients with the disease, researchers found that the stimulant amplified the increase in glucose levels after mealtimes. If blood sugar levels are not controlled, people with type 2 diabetes often go on to develop complications such as heart disease.

The 10 volunteers had a small glucose monitor embedded under the skin in their abdomen. To control the amount of caffeine the participants received, the team gave them pills containing caffeine equivalent to around four cups of coffee in one day or similar looking placebos.

When the volunteers consumed caffeine their average daily sugar levels went up by 8%. "We're not sure what it is about caffeine that drives glucose levels up," said Dr James Lane, at Duke University in North Carolina, who led the study, published in Diabetes Care.

There are currently no guidelines to diabetics to avoid caffeine. "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."

Lane's research appears to contradict a Finnish study in 2004 which found that people who drink more coffee are less likely to develop type 2 diabetes.