From Medscape Medical News
Fran Lowry
July 1, 2010 (Orlando, Florida) — A small proof-of-concept study in adult athletes with type 1 diabetes suggests that ingesting caffeine before exercise may reduce or prevent hypoglycemia. Results were presented here at the American Diabetes Association (ADA) 70th Scientific Sessions.
Currently, adult athletes with type 1 diabetes have very few tools they can use, said Ian W. Gallen, MD, consultant physician at Buckinghamshire Hospitals Trust, High Wycombe, United Kingdom, in a poster presentation.
"All they can do is reduce their shots of insulin or take extra food," said Dr. Gallen, who tries to help young athletes with type 1 diabetes perform better in their sports because of difficulties with hypoglycemia and poor performance."
Dr. Gallen studied 4 men and 1 woman (mean age, 38 years; mean body mass index, 27 kg/m2) who were on a multiple daily injection regimen with glargine-aspart. On study day 1, he measured their maximum oxygen consumption (VO2 max) to assess workload. On day 2, the subjects ingested caffeine, 5 mg/kg, or placebo tablets mixed with a drink, in random order, 2 hours after a meal and insulin injection. They then rested for 30 minutes.
After their rest, the subjects exercised on a stationary bicycle for 10 minutes at 50% VO2 max, and then for another 30 minutes at 70% VO2 max. Work output was measured by gas exchange to ensure that work output was fixed and arterialized blood samples were analyzed throughout the study.
The subjects then were crossed over to placebo or caffeine and the study was repeated.
On the day that the subjects received caffeine, their blood glucose levels stayed up and they did not need glucose, but when they received placebo, their blood glucose levels fell and they needed glucose, Dr. Gallen said.
When receiving placebo, subjects' blood glucose when they began to exercise was 10.3 ± 1.4 mmol/L and decreased to 8.0 ± 1.7 mmol/L during exercise. Two subjects required 20 g of oral glucose to avoid hypoglycemia.
When on caffeine, subjects' blood glucose level when they began to exercise was 13.1 ± 2.1 mmol/L and increased to 15.3 + 3.4 mmol/L during exercise. Glucose was not required for any subject when they were in the caffeine group.
Asked how caffeine augments blood glucose in this setting, Dr. Gallen explained that there is evidence that the counter-regulatory hormone response to exercise is reduced in type 1 diabetes, and caffeine could amplify this poor response, thus making it more normal.
He cautioned that this is a proof-of-concept study, and that larger trials need to be done. Also, the dose of caffeine used in this study was equivalent to twice the daily average for UK caffeine consumption and would not be a practical dose in the real world. Another study is planned with a lower dose of caffeine.
"This method would work very well for unplanned exercise late in the postprandial period when you can't change your shots," Dr. Gallen said. "It would save you having to take extra food and avoid unnecessary weight control."
M. Sue Kirkman, MD, of the American Diabetes Association in Alexandria, Virginia, agreed.
"Hypoglycemia is a big problem, especially with exercise. People can try to prevent it by eating a snack before they exercise or letting their blood sugar run a little higher before they exercise, but those aren't necessarily the healthiest things to do if you have trouble with your weight. If you are having to eat more, this defeats the purpose of exercising," she commented during an interview with Medscape Medical News.
"I think this study is intriguing because it shows that caffeine, which is readily available, can prevent the exercise-induced hypoglycemia in type 1 diabetes. However, it was a small study, just 5 people, and it would need further study, but it is interesting, and it does suggest that something as simple as drinking some coffee might help prevent what really can sometimes be a barrier to people exercising."
Dr. Gallen and Dr. Kirkman have disclosed no relevant financial interests.
American Diabetes Association 70th Scientific Session: Abstract 1184-P. Presented June 26, 2010.
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