Monozygotic twins with congenital adrenal hyperplasia: long-term endocrine evaluation and gene analysis.

Monozygotic female twins with congenital adrenal hyperplasia due to 21-hydroxylase deficiency are described and evaluated over the first 6 years of life. Despite appropriate steroids, NaCl, and fludrocortisone therapies, there was significant fluctuation in the suppression of adrenal steroid secretion. Advanced bone maturation in both was noted. For the first time, molecular genetic analysis was performed and documented that the twins were compound heterozygotes for two different mutations: the maternal allele carried the 8-bp deletion mutation, whereas the paternal allele carried the 1172N missense mutation. Parental DNA samples confirmed that the mutations were on different alleles.

Beta-cell response to intravenous glucagon in African-American and Hispanic children with type 2 diabetes mellitus.

The incidence of type 2 diabetes mellitus (DM) in children and adolescents has substantially increased over the past decade. The present study was conducted to evaluate the beta-cell response to intravenous glucagon (a non-glucose secretagogue) in children with type 2 DM. Twenty pediatric patients with type 2 DM were compared to 15 control subjects matched for body mass index and sexual maturation. The patients' ages ranged between 10 and 19 years. The duration of DM ranged from 1 to 5 years. Nine patients were on insulin treatment and 11 were on diet alone (3 patients) or metformin (8 patients). The criteria for type 2 DM were absent islet cell (IA-2) and glutamic acid decarboxylase (GAD65) antibodies and a fasting serum C-peptide level of > or = 0.23 nmol/l. Plasma glucose and serum C-peptide levels were determined in the fasting state and six minutes after an intravenous injection of 1 mg of glucagon. The fasting and stimulated plasma glucose levels and the fasting serum C-peptide levels (1.02 +/- 0.43 vs 0.79 +/- 0.26 nmol/l, p < 0.05) were higher in the patients with DM compared to weight-matched control subjects. While the absolute C-peptide responses to glucagon were not different between the two groups, the stimulated C-peptide to glucose ratios were significantly lower in the patients with DM compared to controls (0.039 +/- 0.026 vs 0.062 +/- 0.033, p < 0.05). Patients with DM treated with diet or oral therapy had significantly greater basal and stimulated C-peptide concentrations, incremental C-peptide, and C-peptide to glucose ratios than patients on insulin treatment. Both the fasting and the stimulated C-peptide levels were inversely correlated with the duration of DM (r = -0.53, p < 0.05). HbA1c at one year follow-up was inversely correlated with glucagon-stimulated C-peptide levels at the time of the study (r = -0.658, p < 0.01) and positively correlated with the duration of diabetes (r = 0.671, p = 0.002). The apparently normal serum C-peptide levels measured after glucagon challenge in these children with type 2 DM reflect their higher glucose levels. The lower stimulated C-peptide to glucose ratios in these children with type 2 DM compared to normal controls demonstrate their diminished beta-cell response to intravenous glucagon, a non-glucose secretagogue. Among the patients with DM, a higher glucagon-stimulated serum C-peptide response was associated with diet/metformin treatment, a shorter duration of DM and predicted improved glycemic control up to one year later. Thus, the fasting and glucagon-stimulated serum C-peptide levels provide an estimate of the potential insulin secretory capacity of the beta-cell and may predict glycemic control in pediatric type 2 DM.