Minimal model analysis of insulin sensitivity and glucose-mediated glucose disposal in Type 1 (insulin-dependent) diabetic pancreas allograft recipients

Abstract

Decreased insulin sensitivity and glucose-dependent glucose disposal (glucose effectiveness) have been demonstrated in poorly-controlled Type 1 (insulin-dependent) diabetic patients. We have therefore examined the effects of successful pancreas transplantation that results in long-term physiologic normoglycaemia as measured by insulin sensitivity index and glucose effectiveness in 14 Type 1 diabetic recipients (Group 1) using the Bergman minimal model method. Their results were compared with those of five non-diabetic patients with kidney transplant alone (Group 2) and 10 healthy control subjects (Group 3). Mean plasma glucose levels were indistinguishable in Group 1 when compared to Groups 2 and 3. However, mean basal plasma insulin levels were two- and eight-fold greater in Group 1 (36 +/- 6 microU/ml) than in Group 2 (17 +/- 7 microU/ml) and Group 3 (4.5 +/- 0.6 microU/ml), respectively. Following intravenous glucose (t = 0 min) and tolbutamide (t = 20), peak incremental insulin levels were significantly (p less than 0.001) greater in Group 1 vs Groups 2 and 3. Mean insulin sensitivity index was 65% and 50% lower in Group 1 (2.89 +/- 0.45) and Group 2 (4.11 +/- 1.30), respectively, when compared to Group 3 (8.40 +/- 1.24 x 10(-1) min-1 (microU/ml)-1. In contrast, glucose effectiveness was similar in the three groups (Group 1, 2.48 +/- 0.26; Group 2, 2.05 +/- 0.21; and Group 3, 2.10 +/- 0.17 x 10(-2).min-1). We conclude that, despite prednisone-induced insulin resistance, normal glucose tolerance is achieved by hyperinsulinaemia and normalisation of glucose-dependent glucose disposal following pancreas-kidney transplantation in Type 1 diabetic patients.