Effect of glutamine on glucose metabolism in children with Duchenne muscular dystrophy

Background & aims: Glutamine is a potent gluconeogenic precursor and stimulates insulin secretion. Glutamine's effect on glucose metabolism in Duchenne muscular dystrophy (DMD) has never been studied. To determine plasma glucose and insulin concentrations measured during and after glutamine administration in DMD boys. We hypothesized that glutamine can modulate whole body glutamine glucose metabolism in DMD, a genetically determined disease. Methods: As secondary endpoints of a randomized crossover trial in 30 prepubertal DMD boys, we measured fasting blood glucose, insulin and the Homeostasis Model Assessment (HOMA) index after daily oral glutamine (0.5 g kg(-1) d(-1)) for 4 months versus placebo. In a separate time series trial in 6 prepubertal DMD boys, we measured the same endpoints as well as plasma glutamine and whole body glucose turnover (Ra,glc) (primed continuous i.v. infusion of D-[6,6-D-2]glucose), while participants received acute oral glutamine (0.5 g kg(-1) d(-1)) continuously for 5 h. Results: In the randomized trial, baseline measurements of HOMA correlated with age (r = 0,51, p = 0.007) and percent fat estimated by bioelectrical impedance analysis (BIA) (r = 0.39, p = 0.047). After 4 months glutamine supplementation, we observed no treatment or order effect on HOMA or insulin. During acute glutamine for 5 h (time series trial), plasma glutamine doubled and was associated with lincreased plasma insulin concentration (10.42 +/- 2.54 vs 7.32 +/- 1.86, p = 0.05) with no effect on plasma glucose, HOMA or Ra,glc. Conclusions: Acute glutamine transiently stimulates insulin secretion in DMD boys, which could be mediated by plasma glutamine concentrations. Fasting insulin concentration and HOMA might provide quantifiable indices of disease progression. (C) 2012 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.