Drinking coffee before eating cereal - even a low-sugar cereal - can harm the body's blood sugar response and cause blood glucose levels to rise dramatically, say researchers from the University of Guelph.
In this new study, ten healthy men drank roughly two cups (500 ml) of caffeinated coffee, decaf, or water one hour before eating a low-sugar cereal (Kellogg's All Bran) or a moderately sweet cereal (Kellogg's Crispix). Blood samples were taken over several hours to check for caffeine levels, blood sugar and insulin response.
Men who drank caffeinated coffee before eating the low-sugar cereal had higher blood sugar levels than those who drank decaf before eating the sweeter cereal.
Compared to decaf drinkers, blood sugar levels in those who drank caffeinated coffee before eating the low sugar cereal were 250 percent higher a few hours after eating.
Researchers say it's the caffeine in coffee that alters the body's response to sugar. Caffeine increases insulin resistance, which makes blood sugar levels go higher than if no caffeine was consumed.
Insulin resistance, a pre-diabetic state, occurs when normal amounts of insulin are not enough to control blood sugar levels.
For people at risk for diabetes, drinking caffeinated coffee with any carbohydrate-rich food will produce a bigger surge in blood glucose which the body will try to compensate for by producing more insulin.
If you are at risk for diabetes, consider talking to a registered dietitian about managing your blood sugar levels.
This study was published in the May 2008 issue of the American Journal of Clinical Nutrition.
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