C-peptide and glucagon profiles in minority children with type 2 diabetes mellitus

The present study was conducted to determine the extent of insulin deficiency and glucagon excess in the hyperglycemia of type 2 diabetes in children. The incidence of type 2 diabetes mellitus in children and adolescents has increased substantially over the past several years. Because insulin and glucagon action both regulate blood glucose concentration, we studied their responses to mixed meals in children with type 2 diabetes. Subjects were 24 patients with type 2 diabetes compared with 24 controls, aged 9--20 yr (predominantly African-Americans), matched for body mass index and sexual maturation. All of those with diabetes were negative for antibodies to glutamic acid decarboxylase. Plasma glucose, glucagon, and serum C-peptide concentrations were measured at 0, 30, 60, 90, and 120 min after a mixed liquid meal (Sustacal) ingestion (7 mL/kg body weight; maximum, 360 mL). The area under the curve (AUC) was calculated by trapezoidal estimation. The incremental C-peptide (Delta CP) in response to the mixed meal was calculated (peak -- fasting C-peptide). The plasma glucose AUC was significantly greater in patients than in controls (mean +/- SEM, 1231 +/- 138 vs. 591 +/- 13 mmol/L x min; P < 0.001). The Delta CP was significantly lower in those with diabetes than in controls (1168 +/- 162 vs. 1814 +/- 222 pmol/L; P < 0.02). Glucagon responses did not differ between the two groups. Hyperglycemia is known to inhibit glucagon secretion. Therefore, our patients with substantial hyperglycemia would be expected to have decreased glucagon responses compared with controls and are thus relatively hyperglucagonemic. Patients were divided into poorly and well controlled subgroups (glycosylated hemoglobin A(1c), > or =7.2% and or =1 yr; short term,