Caffeinated beverages are not good for patients with type 2 diabetes, based on the findings of a small study reported in Diabetes Care (August 2004). A study of 14 regular coffee drinkers showed a link between caffeine at mealtime and increased glucose and insulin levels. The participants had had type 2 diabetes for at least 6 months, took medications for the disease, but did not require insulin.
For the study, the researchers evaluated how much caffeine the participants drank over a week. Also, the participants were given 2 125-mg caffeine capsules or a placebo, which were taken with a commercial liquid meal (BoostR) that has 75 g of carbohydrates. The patient's blood glucose levels were measured before and after taking the caffeine pills. The results showed that caffeine did not affect glucose and insulin levels after fasting. Yet, the participants who drank the liquid and then took a caffeine pill experienced a 21% rise in glucose and a 48% increase in insulin levels, compared with the participants taking the placebo. The researchers concluded that diabetics should lower or eliminate caffeine in their diets.