Insulin secretory profiles and C-peptide clearance kinetics at 6 months and 2 years after kidney-pancreas transplantation.

Glucose, insulin secretion, and insulin secretory pulses were measured by deconvolution of peripheral C-peptide concentrations in 10 IDDM recipients of a combined kidney-pancreas allograft 6 mo post-transplantation and were compared with 10 matched nondiabetic control subjects. Seven of the 10 recipients were restudied 2 yr post-transplantation. To control for immunosuppressive therapy, 6 patients with a kidney allograft also were studied. Pancreatic insulin secretion rates were evaluated over a 24-h period with three mixed meals. Six months post-transplantation, fasting (5.3 +/- 0.1 vs. 5.3 +/- 0.1 mM), average 24-h (6.0 +/- 0.1 vs. 5.7 +/- 0.1 mM), and meal-related (6.1 +/- 0.3 vs. 5.8 +/- 0.2 mM) plasma glucose levels were not different in control subjects and recipients, respectively. Total 24-h insulin secretion rates were similar between the two groups (150 +/- 15 vs. 182 +/- 24 nmol.m-2.24 h-1). However, post-transplantation, the relationship between basal and meal-stimulated insulin secretion was altered with increased basal insulin secretion (52.2 +/- 6.4 vs. 97.4 +/- 12.5 pmol.m-2.min-1, P less than 0.004) and reduced meal-related secretion. The proportion of total 24-h insulin secretion comprised by basal secretion was 44 +/- 4% in the control subjects vs. 73 +/- 5% in recipients. The number of ultradian oscillations of insulin secretion identified in each 24-h period by pulse analysis was similar in control subjects and recipients (11.9 +/- 0.9 vs. 10.4 +/- 0.5 oscillations/24 hr).(ABSTRACT TRUNCATED AT 250 WORDS)