Metabolic effect of islet B-cell function in insulin-treated diabetes

Abstract

We studied the relationship between endogenous insulin secretion and fasting levels of plasma free fatty acids (FFA), plasma acetoacetate plus plasma 3-hydroxybutyrate (total ketone bodies), blood glucose, and HbAl in 132 diabetic outpatients treated with conventional insulin regimens. Patients were divided into four groups according to plasma C-peptide concentration after intravenous stimulation with glucagon: one group with C-peptide stimulation <0.06 nmol/1, one group with C-peptide stimulation 0.06<0.32 nmol/1, one group with C-peptide stimulation 0.32-<0.60 nmol/1, and one group with C-peptide stimulation 0.60 nmol/1. According to clinical criteria the prevalence of insulin-dependent diabetes mellitus was approximately 90% in patients with C-peptide stimulation <0.32 nmol/1, approximately 25% in patients with C-peptide stimulation from 0.32-<0.60 nmol/1, and approximately 10% in patients with C-peptide stimulation ×0.60 nmol/1. All metabolic variables were significantly higher in patients without detectable C-peptide in plasma when compared to values found in patients with C-peptide stimulation from 0.06-<0.32 nmol/1. These two patient groups also had similar peripheral plasma free insulin levels and were comparable according to age, sex, and body mass index. In a subgroup of 25 patients with C-peptide stimulation <0.06 nmol/1 matched according to sex and HbAl value with 25 patients with C-peptide stimulation from 0.06-<0.32 nmol/1 the higher values of FFA and fasting blood glucose were still found among patients of the former group. In conclusion, preserved C-peptide secretion protects against elevations in overnight fasting values of FFA, ketone bodies, and blood glucose in insulin treated diabetic outpatients. The protection effect against ketogenesis and hyperglycaemia may, in part, be due to a direct effect of portal insulin on the liver.

Key Words:

• endogenous insulin secretion
• C-peptide
• free fatty acids
• glycosylated haemoglobin
• insulin treated diabetes
• ketone bodies
• metabolic control
• Hans J. Gjessing