Effects of Glutamine on Glycemic Control During and After Exercise in Adolescents With Type 1 Diabetes

Abstract

OBJECTIVETo investigate if oral glutamine ameliorates exercise and postexercise nighttime hypoglycemia in type 1 diabetic adolescents.RESEARCH DESIGN AND METHODSTen adolescents (15.2 ± 1.4 years [SD], A1C 6.9 ± 0.9%) on insulin pumps were studied. The subjects were randomized to receive a glutamine or placebo drink pre-exercise and at bedtime (0.25 g/kg/dose). A 3:00 p.m. exercise session consisted of four 15-min treadmill/5-min rest cycles. Pre-exercise blood glucose was 140–150 mg/dl and was monitored throughout the night. Studies were randomized crossover over 3 weeks.RESULTSBlood glucose levels dropped comparably (52%) during exercise on both days. However, the overnight number of hypoglycemic events was higher on glutamine than placebo (≤70 mg/dl, P = 0.03 and ≤60, P = 0.05). The cumulative probability of nighttime hypoglycemia was increased on glutamine days (80%) versus placebo days (50%) (P = 0.02).CONCLUSIONSGlutamine increased the cumulative probability of postexercise overnight hypoglycemia compared with placebo in adolescents with type 1 diabetes. Whether glutamine may enhance insulin sensitivity postexercise requires further study in type 1 diabetes.

Does oral glutamine improve insulin sensitivity in adolescents with type 1 diabetes?

“…Consistent with an earlier preliminary report [17], the present study demonstrates that GLN supplementation acutely increases the likelihood of postexercise, overnight hypoglycemia in adolescents with T1D. These data demonstrate that after strenuous exercise, GLN decreases glucose production or increases glucose utilization in T1D.…”

“…BG was titrated (129 ± 37 mg/dL) before exercise at 1500 h. Children were randomized to receive a drink containing either GLN (0.25 g • kg −1 •dose −1 ) or PL (calorie- and nitrogen-free) before exercise, at bedtime, and at 0530 h the following morning. The dose (0.75 g • kg −1 • 24 h −1 ) was chosen to match doses used in clinical trials in other settings [11–13] and found to affect BG in our earlier study [17]; such doses are of the same order of magnitude as endogenous GLN production (348 μmol • kg −1 • h −1 , i.e., 1.2 g • kg −1 • d −1 ) [18]. …”

“…The exercise sessions consisted of four consecutive 15-min treadmill cycles with 5-min rest breaks, for a total of 75 min as previously described [17]. BG concentration was checked during each rest period and 30 min after exercise.…”

“…Recent studies suggest GLP-1 reduces endogenous glucose production through mechanisms independent of insulin [15] and GLP-1 improved insulin sensitivity in rodents [16]. Lower nighttime blood glucose concentrations after afternoon exercise sessions in adolescents with T1D who received oral GLN compared with placebo (PL) have been observed [17]. As adolescents with T1D have no significant endogenous insulin production, we hypothesized that GLN had a role in modulating insulin sensitivity.…”

Glutamine Supplementation in Sick Children: Is It Beneficial?

“…A recent randomized crossover pilot study in children with type 1 diabetes has investigated whether oral Gln could improve hypoglycaemia during exercise and overnight after exercise [229]. Ten adolescents (mean age 15.2 ± 1.4 y) on insulin pumps were randomized to receive a drink containing Gln or placebo preexercise and at bedtime (0.25 g/kg/dose).…”