| Abstract: | Peripheral insulin action and cellular insulin binding were studied in 10 newly detected, obese, black, Southern African women with Type 2 diabetes mellitus before and after midterm oral sulphonylurea therapy and in five obese, non-diabetic controls. Glucose disposal (assessed by the euglycaemic insulin clamp technique) was significantly reduced in diabetic patients compared to control subjects (4.4 ± 0.5 vs 6.4 ± 0.5 mg kg-1 min-1, p < 0.05), and increased after 1 and 3 months of sulphonylurea therapy to 6.8 ± 0.6 mg kg-1 min-1 (p = 0.01) and 6.3 ± 0.7 mg kg-1 min-1 (p = 0.04), respectively. The major change in the binding kinetics of insulin to peripheral monocytes was an increase in the mean receptor concentration in the diabetic patients which was significant after 3 months of therapy (0.2 ± 0.08 to 0.6 ± 0.01 nM, p = 0.05). The basal plasma C-peptide concentration was significantly lower in the diabetic patients than in the controls and remained so following sulphonylurea therapy, despite significant reductions in fasting glucose and HbA-1 concentrations. We conclude that newly diagnosed, obese, black Southern Africans with Type 2 diabetes showed diminished peripheral glucose disposal which increased following sulphonylurea therapy. This was accompanied by an increase in insulin receptor concentration but not with changes in basal insulin secretion. |
