Endocrine Abstracts

Introduction: Monotherapy failure in diabetes mellitus type 2 occurs early in the course of disease. Evaluation of the primary pathogenetic mechanism is of primary importance in choosing the optimal combination therapy.

Objectives: To investigate influence of meal stimulated C-peptide levels and HOMA B, as markers of residual insulin secretion on the efficasy of adding metformin to sulphonylurea therapy in subjects with metabolic syndrome, type 2 diabetes and sulphonylurea failure.

Method: In the group of thirty subjects with diabetes type 2, metabolic syndrome and SU monotherapy failure, metformin was added on (SU+MET) for the six months. During the six months following-up, fasting (FPG), postprandial (PPG), mean daily plasma glucosae (MPG) and glycosylated hemoglobin (A1C) were evaluated. Fasting and stimulated C- peptide levels after standard meal test (300 kcal) were measured at start; absolute and relative increase of C-peptide (delta CP, delta CP%), and HOMA B were calculated. Correlation between markers of residual insulin secretion at start and glycaemic control after six months of SU+MET therapy were evaluated by using Pearson correlation coefficient.

Results: Glycaemic control after six months of SU+MET therapy was significantly improved (FPG 7.89 vs 11.61 mmol/l, P<0.01; PPG 12.61 vs 11.12 mmol/l, P<0.01; MPG 9.32 vs 11.78 mmol/l; A1C 7.81 vs 9.73%, P<0.01), but target values were not reached. Stimulated C-peptide levels inversely correlated high singnificantly, with all parameters of glycaemic control (r −0.479 to −0.791; P< 0.01). HOMA B significantly correlated only with A1C (r=−0.382; P<0.05). However, fasting C- peptide levels were found not to correlate with parametars of glycaemic control.

Conculsion: Not only presence of metabolic syndrome, but also evaluation of residual insulin secretion are necessary in the choosing the best combination therapy in type 2 diabetic subjects. Standard meal stimulated C- peptide level is a simply and useful marker of residual insulin secretion.