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

Abstract

Objective: The decline in insulin sensitivity (SI) associated with puberty increases the difficulty of achieving glycemic control in adolescents with type 1 diabetes (T1D). The aim of this study was to determine whether glutamine supplementation affects blood glucose by enhancing SI in adolescents with T1D.

Methods: Thirteen adolescents with T1D (HbA1C 8.2 ± 0.1%) were admitted to perform afternoon exercise (four 15-min treadmill/5-min rest cycles of exercise) on two occasions within a 4-wk period. They were randomized to receive a drink containing either glutamine (0.25 g/kg) or placebo before exercise, at bedtime, and early morning in a double-blind, crossover design. Blood glucose was monitored overnight, and a hyperinsulinemic-euglycemic clamp was performed the following morning.

Results: Blood glucose concentration dropped comparably during exercise on both days. However, the total number of nocturnal hypoglycemic events (17 versus 7, P = 0.045) and the cumulative probability of overnight hypoglycemia (50% versus 33%, P = 0.02) were higher on the glutamine day than on the placebo day. During clamp, glucose infusion rate was not affected by glutamine supplementation (7.7 ± 1 mg • kg-1 • min-1 versus 7.0 ± 1; glutamine versus placebo; P = 0.4).

Conclusions: Oral glutamine supplementation decreases blood glucose in adolescents with T1D after exercise. Insulin sensitivity, however, was unaltered during the euglycemic clamp. Although the mechanisms involved remain to be elucidated, studies to explore the potential use of glutamine to improve blood glucose control are needed.

Keywords: Amino acids; Exercise; GLP-1; Hyperinsulinemic-euglycemic clamp clamp; Hypoglycemia; Stable isotopes.

Conflict of interest statement

The authors have no conflicts of interest to declare.

Copyright © 2016 Elsevier Inc. All rights reserved.

Figures

Fig. 1

Protocol design to assess the effect of glutamine on insulin sensitivity in children with type 1 diabetes.

Fig. 2

Cumulative probability of nighttime hypoglycemia (BG ≤70 mg/dL) if the same adolescent with type 1 diabetes mellitus took glutamine or placebo before afternoon exercise and at bedtime.

Fig. 3

GIR during high-dose hyperinsulinemic-euglycemic clamp after participant received glutamine or placebo. Individual changes are depicted by lines joining individual data points. GIR, glucose infusion rate.