As if jumpy nerves and yellow teeth weren't enough, U.S. researchers have discovered one more reason to kick caffeine.
In a study of coffee drinkers with Type 2 diabetes, Duke University psychologist James Lane found that caffeine boosted blood sugar levels by an average of 8 per cent.
Dr. Lane and his team employed a cutting-edge glucose monitor embedded beneath stomach skin, which allowed them to scrutinize subjects during their daily routines.
"This is a first," Dr. Lane said. "We've never been able to see the effects we found in the lab in the real world before."
Study participants, all of whom usually drink two or more coffees a day, swallowed capsules containing the caffeine equivalent of four eight-ounce cups of coffee.
Compared with results from a placebo, the glucose monitors registered significant surges in sugar, especially following meals: 9 per cent after breakfast, 15 per cent after lunch and 26 per cent after dinner.
The 10 participants could not consume any other form of caffeine during the study.
The findings will be published in the February issue of Diabetes Care.
"Our study suggests that one way to lower blood sugar is to simply quit drinking coffee," said Dr. Lane, who's been examining caffeine's effects on health for 25 years.
The researchers couldn't say for sure why caffeine increases glucose levels. Dr. Lane suggests that adrenalin and other stress hormones released when coffee enters the body could go on to stimulate glucose secretion in the liver.
Considering his findings, Dr. Lane says that guidelines warning diabetes patients against caffeine may not be far off.
"The general population should definitely be more aware of the effects of caffeine as a powerful drug."
