Increased Endogenous Insulin Secretion in Diabetic Patients after Insulin Therapy

Abstract

It is not infrequently observed that the insulin dose required for the control of diabetes is markedly reduced in the course of insulin therapy. It might be due to either the reduction in insulin antagonists, or the augmentation of endogenous insulin secretion. The present investigation was undertaken to evaluate the influence of insulin treatment on the insulin secretory capacity of diabetic patients.
Seven adult-onset diabetic subjects, not having been treated with insulin, were studied. Their FBS values were over 220mg % and they had no other diseases which might affect carbohydrate metabolism. To these patients, MC lente insulin (Monotard, Novo) was administered until their diabetic metabolism was controlled. The periods of insulin therapy varied from 14 to 32 days, After these periods, the serum 125I-insulin binding rate of the patients did not show a significant increase.
The observation of the diurnal cycles in the blood glucose and IRI levels and 100g OGTT were performed before therapy and on the third and fourth day after the withdrawal of insulin injections after control was achieved. IRI responses to the three daily meals which had been found almost absent or very low before therapy, were significantly ameliorated. The total integrated IRI area in its diurnal cycle was increased from 98.9±23.7 to 186.1±37.7μh/m/(p<0.05). In 100g OGTT, the lowered blood sugar levels and increased IRI responses were demonstrated after therapy in a similar manner to those of the diurnal cycles. However, IRI responses to meals or glucose loadings were not markedly ameliorated after insulin t' erapy in cases with diabetes of a long duration.
It is concluded that endogenous insulin secretion could be increased in diabetic patients by metabolic control with exogenous insulin injections so long as the insulin secretory capacity is at least partially preserved.