Depletion of glutathione, an important antioxidant present in red cells, has been reported in type 1 diabetes, but the mechanism of this depletion has not been fully characterized. Glutathione depletion can occur through decreased synthesis, increased utilization, or a combination of both. To address this issue, 5-h infusions of L-[3,3-2 H 2 ]cysteine were performed in 16 diabetic adolescents divided into a well-controlled and a poorly controlled group and in eight healthy nondiabetic teenagers as control subjects (HbA 1c 6.3 ؎ 0.2, 10.5 ؎ 0.6, and 4.8 ؎ 0.1%, respectively). Glutathione fractional synthesis rate was determined from 2 H 2 -cysteine incorporation into blood glutathione. We observed that 1) erythrocyte cysteine concentration was 41% lower in poorly controlled patients compared with well-controlled patients (P ‫؍‬ 0.009); 2) erythrocyte glutathione concentration was ϳ29% and ϳ36% lower in well-controlled and poorly controlled patients compared with healthy volunteers; and 3) the fractional synthesis rate of glutathione, although similar in well-controlled and healthy subjects (83 ؎ 14 vs. 82 ؎ 11% per day), was substantially higher in the poorly controlled group (141 ؎ 23% per day, P ‫؍‬ 0.038). These findings suggest that in diabetic adolescents, poor control is associated with a significant depletion of blood glutathione and cysteine, due to increased rates of glutathione utilization. This weakened antioxidant defense may play a role in the pathogenesis of diabetes complications. Diabetes

Background: Metabolic syndrome (MS)-related comorbidities in obesity, such as hypertension, dyslipidemia, and glucose intolerance, are increasingly recognized in children, predisposing them to early cardiovascular disease.

A method is described whereby the concentrations and 2H isotope enrichment of glutathione (GSH) and cysteine can be simultaneously determined in a single gas chromatography-mass spectrometry run following derivatization as their N,S-ethoxycarbonyl methyl esters. Improvements of the derivatization protocol and the use of a short gas chromatography column combined with single-ion monitoring allow for rapid quantification of these parameters with acceptable precision and reproducibility (coefficient of variation less than 5%). The method makes possible their quantitative measurement in very small volumes (50 microL) of human umbilical cord blood, and is thus suitable for determining the cysteine and GSH concentrations and 2H isotope enrichments in blood samples from neonates or in other conditions in which sample size is restricted. It is shown that the fractional synthesis rate of human umbilical erythrocyte lysates in vitro is several-fold greater than that measured in vivo.