[Insulin metabolism in obese children tested by oral and intravenous glucose loading]

Authors performed 0.5 g/kg intravenous and 1.75 g/kg p.os glucose tolerance tests in 25 alimentary obese children. C-peptide and Immunoreactive Insulin determinations were performed in every case. The average ratio of the two peptide during i.v. loads was calculated, too. Results were compared with the data of 6 children with ideal body weight respectively, whose results were obtained in similar circumstances. They find that i.v. glucose load produces different degrees in detected by C-peptide insulin secretion in normal as well as in obese children and the secretion rate is practically permanent till the end of the test in both groups. The low C-peptide/insulin ratio during i.v. glucose tolerance test in obese children indicates insulin resistance and explains decreased glucose tolerance. The "early-phase insulin release" detected in insulin curves of i.v. glucose load is resulted not only by the insulin reservoir capacity of beta-cells, but also by the insulin excretion capacity of the liver and the receptor activity of target cells. There is no connection between maximum glucose level responses to i.v. load and maximum C-peptide and insulin responses, whereas increases in maximum C-peptide response are parallel with those of in weight. C-peptide responses, being different in degree and experienced during the two types of tolerance test, support the "incretin" phenomenon. This mechanism may be important in the development of beta-cell hyperfunction which has been proved in obesity.