If you have type II diabetes, drinking coffee or tea could be making it worse. Drinking four or more cups of coffee or tea could be raising blood sugar levels by an average of 8 per cent over the day, researchers have discovered.
The effect varied during the day, depending on when caffeine was consumed. Coffee at breakfast time raised blood sugar levels by nine per cent, at lunch by 15 per cent, and after an evening meal by 26 per cent.
The discovery ties in with earlier research that discovered coffee increases the body's resistance to insulin, the hormone that manages the response to glucose levels in the blood. While this is not a problem in healthy people, it seems to interfere with the process that moves glucose from the blood and into muscle and other cells in the diabetic.
Caffeine may also trigger the release of adrenaline, which can also raise blood sugar levels.
The study results certainly aren't the final word. It involved just 10 patients and over a short period of just 72 hours.
(Source: Diabetes Care, 2008; 31: 221-2).