A cup of coffee at breakfast may be making an individuals diabetes worse, report researchers who conducted a study to determine how caffeine impacts blood sugar control and insulin levels. Early studies done suggest, drinking two cups of instant coffee a day significantly impaired glucose tolerance in men with type 2 diabetes. More recent studies have associated caffeine with decreased insulin sensitivity in young adults without diabetes.
In a study done by investigators from Duke University standard tests for diabetes were given to 14 regular coffee drinkers with type 2 diabetes. First, the participants had a fasting blood sugar test, followed by the ingestion of a capsule containing caffeine or placebo. The fasting blood sugar test was then repeated to determine how caffeine affected blood sugar. Second, the participants were given an additional capsule with either caffeine or placebo along with a meal so researchers could see how caffeine taken with carbohydrates would impact their diabetes.
Results showed caffeine alone had no effect on blood sugar or insulin when compared with the placebo capsule. However, when taken with food, caffeine significantly raised blood sugar and had detrimental effects on insulin.
Researchers say their results raise concerns about the potential hazards of caffeine for patients with type 2 diabetes and possibly for individuals who are glucose intolerant or 'pre-diabetic.'