Caffeine is a stimulant found naturally in a variety of seeds and leaves. The drug is consumed by over 90 percent of the world population, according to Rochester College, often in coffee, tea or soda. Although too much caffeine can cause nervousness, insomnia and anxiety, caffeine in moderation can be beneficial. The effect of caffeine on insulin has been the subject of numerous research studies.
Caffeine and Insulin Sensitivity
Research published in "Diabetes Care" in 2002 found that caffeine decreased insulin sensitivity in participants. Twelve healthy volunteers were administered caffeine or a placebo by researcher Gerben B. Keijzers and colleagues. The study found that caffeine decreased insulin sensitivity by 15 percent compared with a placebo. Another study published in "Diabetes" investigated caffeine's role in exercise and insulin. Researchers found that consumption of caffeine decreased whole body glucose by 30 percent. The study also demonstrated that caffeine reduces the beneficial effects of exercise on muscle insulin action.
Caffeine and High-Carbohydrate Meals
Caffeine may help reduce insulin sensitivity when taken with a high-carbohydrate meal. A study published in "British Journal of Nutrition" provided ten healthy male participants with either caffeinated coffee, decaffeinated coffee or water along with a high-sugar cereal. Three hours later, participants received a 75 g oral glucose tolerance test. The participants who consumed caffeine had high blood glucose and higher insulin levels than the groups who ingested decaffeinated coffee or water. Researcher Lesley L. Moisey and colleagues suggested that caffeine was helpful in managing insulin levels with high-sugar foods.
Caffeine and Type 2 Diabetes
A study published in "Diabetes Care" found that caffeine may raise blood sugar in people with type 2 diabetes. Glucose detection devices were implanted in the skin of ten participants with type 2 diabetes. Some participants were given a caffeine pill equal to four cups of coffee, while others were given a placebo pill. Dr. James Lane, a psychologist at Duke University Medical Center who led the study, found that drinking the equivalent of four cups of coffee per day or more raised blood sugar by 8 percent in people with diabetes compared with diabetic patients who consumed non-caffeinated drinks.
Caffeine and Insulin Resistance
Caffeine may impair blood glucose management and insulin sensitivity, according to a study published in the "American Journal of Clinical Nutrition." Researcher Lesley L. Moisey and colleagues studied ten healthy men in four randomized trials. The participants ingested caffeine or decaffeinated coffee followed by a high- or low-glycemic-index cereal one hour later. Researchers discovered that caffeinated coffee with either meal significantly impaired glucose management. However, further research is needed to determine if caffeine is a risk factor for insulin resistance.
References
- Rochester College: Caffeine
- "Diabetes Care"; Caffeine Can Decrease Insulin Sensitivity in Humans; Gerben B. Keijzers, et al.; Februrary 2002
- "Diabetes"; Caffeine-Induced Impairment of Insulin Action but Not Insulin Signaling in Human Skeletal Muscle Is Reduced by Exercise; Farah S.L. Thong, et al.; March 2002
- "British Journal of Nutrition"; Consumption of Caffeinated Coffee and a High Carbohydrate Meal Affects Postprandial Metabolism of a Subsequent Oral Glucose Tolerance Test in Young, Healthy Males; Lesley L. Moisey, et al.; March 2010
- "American Journal of Clinical Nutrition"; Caffeinated Coffee Consumption Impairs Blood Glucose Homeostasis in Response to High and Low Glycemic Index Meals in Healthy Men; Lesley L. Moisey, et al.; May 2008
- "Diabetes Care"; Caffeine Increases Ambulatory Glucose and Postprandial Responses in Coffee Drinkers With Type 2 Diabetes; James Lane, et al.; February 2008
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