HUMAN C-PEPTIDE .3. DYNAMICS OF SECRETION OF BETA-CELLS IN ADULT DIABETICS FOLLOWING GLIBENCLAMIDE-GLUCOSE IV (HUMAN C-PEPTIDE-III)

Adult diabetics were divided into 4 groups according to therapy before and after a therapeutic trial with diet and glibenclamide: I: insulin before - insulin afterwards, II: tablets - insulin, III: insulin - tablets and IV: tablets - tablets. The secretion capacity of the beta-cells, determined by C-peptide was examined in 6 healthy subjects and in 10 diabetics of each group following an i.v. glibenclamide-glucose load. A decreased insulinogenic reserve showing itself in a reduced and delayed rise of immunomeasurable C-peptide (IMCP) was found in all diabetics. However, the secretion of IMCP lasted longer in the diabetics requiring tablets than in the healthy subjects. The average values for the increment of IMCP and the integrated stimulation areas were much more considerable in the patients treated with tablets (III+IV) than in the insulin-dependent patients (I+II). An analysis of variance was performed for the diabetics depending on insulin, on the one hand, and the patients depending on tablets on the other. Between groups I and II the group average values for IMCP are significantly different while differences in the time course of the IMCP mean values of both groups are accidental. Neither the group average values of IMCP nor the time course of the IMCP mean values show significant differences between groups III and IV. The time course of IMCP was described by a regression polynomial of 2nd degree in insulin-dependent diabetics and a polynomial of 4th degree in diabetics depending on tablets; the corresponding curves differ considerably as to extent and steepness of their rise. Prediction of suitable diabetes therapy from an i.v. glibenclamide-glucose load based on blood glucose evaluation up to now is easier and more reliable since C-peptide levels are known. A development of the residual beta-cell function from the stage in groups III and IV via group II to the stage in group I is likely to be the natural course of adult diabetes. © 1978 Springer-Verlag.