DURHAM, NORTH CAROLINA. Drinking coffee with a meal may not be a good idea for patients with type 2 diabetes. Researchers at Duke University recently investigated the effects of caffeine ingestion on glucose and insulin control in a group of 14 type 2 diabetics (average age of 61 years) who were habitual coffee drinkers with an estimated daily caffeine consumption of 525 mg/day. The participants' average fasting glucose level was 7.5 mmol/L (134 mg/dL). The participants were tested on two different days within a 2- week period receiving either placebo capsules or capsules containing 125 mg of caffeine. After an overnight fast, they had blood samples drawn before and an hour after swallowing either two caffeine capsules or two placebo capsules. Subsequently, they ingested another caffeine or placebo capsule with a commercial liquid meal containing 75 mg carbohydrate. Additional blood samples were drawn one and two hours after the meal.
The researchers found no differences in glucose level or insulin response between the placebo and caffeine
consumers as far as the fasting levels were concerned. However, both glucose and insulin levels (area
under the curve) were elevated (by 21% and 48% respectively as compared to placebo) after consuming the
liquid meal accompanied by a caffeine capsule. This exaggerated response is not present among non-
diabetics. The researchers conclude that consumption of caffeinated beverages with meals could produce
higher average glucose levels in diabetics, thus increasing the risk of complications.