Insulin action and insulin binding following pancreas transplantation

Insulin action and insulin specific binding to erythrocytes were examined in ten recipients of a pancreatic segment and renal graft (Group 1), in nine non-diabetic kidney recipients (Group 2) and in ten age- and weight-matched healthy control subjects (Group 3). All transplant recipients were normoglycaemic without need of insulin, received the same immunosuppression and had good renal graft function at 11-18 months post-transplantation, when the investigation was performed. Using the insulin clamp technique, insulin action was expressed as the metabolic clearance rate of glucose at insulin infusion rates of 1.0 (MCRsubmax) and 10.0 (MCRmax) mU.kg-1.min-1. In comparison with the healthy control subjects, fasting free insulin and C-peptide levels were significantly higher in Groups 1 and 2, but no differences between Groups 1 and 2 were found (p greater than 0.05). Mean values +/- SEM of MCRsubmax in Groups 1, 2 and 3 were 6.30 +/- 0.55, 6.09 +/- 0.69 and 10.52 +/- 1.10 ml.kg-1.min-1 respectively, and of MCRmax 12.65 +/- 0.78, 13.14 +/- 0.92 and 19.28 +/- 1.42 ml.kg-1.min-1 respectively. Insulin action was significantly decreased in Groups 1 and 2 at the low as well as the high insulin infusion rates but there was no difference between the two groups of recipients (p greater than 0.05). No differences in binding data (specific binding, number of binding sites per cell) were found. It is concluded that insulin resistance is common to all immunosuppressed organ recipient and is not related to the pancreas graft. The decrease maximal response to insulin and normal insulin binding to erythrocytes tend to suggest a post-receptor defect in insulin action.