(NaturalNews) Coffee-loving diabetics, watch out! Although some studies have shown that coffee drinking may actually help prevent or regulate diabetes, the evidence seems to suggest that caffeine actually worsens diabetic symptoms. In fact, caffeine appears to outweigh all the benefits that coffee would otherwise provide.
Researchers from Duke University have conducted several studies into the effects of caffeine on people with type 2 diabetes. One such study, published in the journal Diabetes Care in 2004, looked at 11 men and three women who regularly drank the equivalent of about four cups of coffee per day.
Participants were either given caffeine in the form of gelatin capsules mixed with dextrose, or were given a placebo pill of dextrose alone. Those in the experimental group received 250 mg of caffeine, taken with water. An hour later, they were given another 125 mg of caffeine along with a commercial liquid meal containing 75 mg of carbohydrates.
The researchers found that while caffeine did not affect fasting levels of glucose or insulin response, it did worsen diabetic symptoms after the meal compared with the placebo. When taken with food, caffeine increased blood levels of insulin by 48 percent and increased blood sugar by 21 percent relative to the placebo.
Caffeine increases daily blood sugar
In 2008, the same researchers published a follow-up study in the journal Diabetes Care. They placed continuous blood sugar monitors on 10 participants, all of whom had type two diabetes and averaged four cups of coffee per day. Instead of drinking coffee, the participants were assigned to take one 250 mg caffeine capsule at breakfast and another at lunch; this totaled an amount of caffeine equivalent to that the participants normally consumed. On a separate day, the participants were instead assigned to take placebo pills.
When the participants took caffeine, their average daily blood sugar levels were 8 percent higher than on days they took a placebo. As in the first study, their blood sugar levels also spiked higher immediately following meals when they had taken caffeine.
"These are clinically significant blood-sugar elevations due to caffeine," researcher James D. Lane said.
Lane noted that the increase in blood sugar seen from caffeine was equivalent to the decrease gained from diabetes drugs - suggesting that drinking caffeine might actually cancel out the effect of diabetes medication.
"For people with diabetes, drinking coffee or consuming caffeine in other beverages may make it harder for them to control their glucose," he said.
In a seeming contradiction, some studies have actually shown that high coffee consumption may decrease a person's risk of diabetes. According to diabetes researcher Rob van Dam, this is due to other chemicals that naturally occur in coffee; unfortunately, the beneficial effect of these compounds seems to be canceled out by caffeine.
"We did do one study where we put caffeine in decaf coffee, and still we saw the same exaggeration of glucose after meals in people with diabetes," van Dam said. "So it seems those other compounds in coffee certainly don't eliminate the caffeine effect we have seen."