Caffeine, a stimulant found in beverages and foods including coffee, tea, soft drinks and chocolate, works by blocking adenosine, a brain chemical that slows your body down. This results in more energy and alertness. Although caffeine increases energy, it may also raise blood sugar levels.
Type 2 Diabetics
Scientists at the University of Guelph in Canada investigated the impact of caffeine ingestion on oral glucose tolerance test results in type 2 diabetic men. Participants ingested caffeine or a placebo and, three hours later, consumed 75 g of glucose. Researchers discovered that those in the caffeine group had higher blood glucose levels after consuming 75 g of glucose than those who had a placebo. The findings were published in the October 2004 issue of the “Journal of Nutrition.”
Healthy People
Caffeine may also increase blood sugar levels in healthy men, according to a study conducted by researchers at the University of Guelph in Canada. Subjects received caffeinated coffee or a placebo with a high or low glycemic index cereal. A high glycemic index cereal digests fast, whereas a low glycemic index cereal digests slowly. Researchers found that those in the caffeinated coffee group experienced greater increases in blood glucose levels after eating either cereal, compared with those who had a placebo, according to research reported in the May 2008 issue of the “American Journal of Clinical Nutrition.”
Additional Research
In yet another study, researchers at the University of Guelph in Canada studied the effects of caffeinated coffee on glucose levels in healthy young men. They assigned subjects to one of the following groups: caffeinated coffee, decaffeinated coffee, or water. Each beverage was consumed with a high glycemic meal and, three hours later, subjects ingested 75 g of glucose. Researchers found that those in the caffeinated coffee group had higher glucose levels after consuming 75 g of glucose than those in the other groups, according to research published in the March 2010 issue of the “British Journal of Nutrition.”
Side Effects
If you decide to ingest caffeine, keep in mind that excess caffeine consumption, defined as more than 500 to 600 mg, can lead to side effects, including insomnia and nervousness, according to the Mayo Clinic. If you’re pregnant or taking medications, consult your health care provider before ingesting caffeine.
References
- "Journal of Nutrition"; Caffeine Ingestion Before an Oral Glucose Tolerance Test Impairs Blood Glucose Management in Men With Type 2 Diabetes; L.E. Robinson, et al.; October 2004
- "American Journal of Clinical Nutrition"; Caffeinated Coffee Consumption Impairs Blood Glucose Homeostasis in Response to High and Low Glycemic Index Meals in Healthy Men; L.L. Moisey, et al.; May 2008
- "British Journal of Nutrition"; Consumption of Caffeinated Coffee and High Carbohydrate Meal Affects Postprandial Metabolism of a Subsequent Oral Glucose Tolerance Test in Young, Healthy Males; L.L. Moisey et al.; March 2010
- MayoClinic.com; Caffeine: How much is too much?; March 2011
