Paper of the Month – February 2016

Zaharieva DP, Miadovnik LA, Rowan CP, Gumieniak RJ, Jamnik VK, Riddell MC. Effects of acute caffeine supplementation on reducing exercise-associated hypoglycaemia in individuals with Type 1 diabetes mellitus.
Diabet Med. 2015 Jul 14. doi: 10.1111/dme.12857.

From the authors: Overall, regular exercise is good for people living with diabetes. However, people with type 1 diabetes, who must take insulin for survival, often find that prolonged aerobic exercise causes blood sugar levels to drop to dangerously low levels (called hypoglycemia). Severe hypoglycemia dramatically decreases exercise performance and may result in disorientation, loss of consciousness and even convulsions and death. Caffeine is a central nervous system stimulant that also appears to have potent effects on energy metabolism during rest and during exercise (see Zaharieva et al., Appl Physiol Nutr Metab 2013 for a review). Caffeine acts centrally to block the action of adenosine on its receptor and prevents the onset of drowsiness and can increase exercise endurance performance. Caffeine also stimulates certain portions of the autonomic nervous system to increase blood glucose rate of appearance by the liver and reduce glucose rate of disappearance into skeletal muscle. Caffeine also increases the body’s reliance on lipid as fuel.

This study tested the hypothesis that the metabolic actions of caffeine would help prevent exercise-induced low blood sugar in patients with type 1 diabetes. Thirteen volunteers (8 females; 5 males) with type 1 diabetes consumed either a caffeine supplement (6mg/kg body mass) or placebo 15 minutes before 45 minutes of moderate-intensity treadmill running (~60% VO2max). Compared with placebo, caffeine intake reduced the rate of decline in blood glucose concentrations during the exercise and in early recovery. It worked equally well in males and in females. However, in late recovery during sleep the evening after exercise, caffeine intake was associated with more late-onset hypoglycemia. This study is the first to explore the short and long-term effects of caffeine intake on exercise metabolism and recovery in type 1 diabetes. In summary, caffeine intake at this dose appears to confer modest protection against exercise-induced hypoglycemia but may increase post exercise- late onset hypoglycemia risk.