Long-term metabolic function of pancreas transplants and influence of rejection episodes

Pancreas grafts, when not rejected, can sustain an insulin-independent state in type I diabetic recipients for indefinite periods. To what extent the metabolic control achieved approaches that of normal individuals, the relationships between graft endocrine and exocrine function, the effect of reversible rejection episodes on subsequent graft function, and the correlation between the results of serial tests of graft function were determined by studies at 1 month, 1 year, and 2 years in a cohort of 39 recipients (29 females, 10 males; mean age (+/- SD), 33 +/- 5 years; mean duration of diabetes, 22 +/- 6 years) of bladder-drained pancreas transplants performed between November 1984 and December 1988. Fifteen patients received a pancreas transplant alone, 8 a pancreas after a kidney, and 16 a simultaneous pancreas/kidney transplant. Graft endocrine function was tested by a 24-hr metabolic profile of blood glucose levels before meals, at 1 and 2 hr after meals, and during the night (14 values in all), by intravenous and oral blood glucose tolerance tests, and by glycosylated hemoglobin levels (HA1 and HA1c). Graft exocrine function was assessed by urine amylase activity (U/hr). The results of the tests in the recipients were subjected to paired comparisons between timepoints and at each timepoint to the results of the same tests in 55 normal nondiabetic control individuals. The means of the mean 24-hr profile glucose (mg/dl) values were significantly lower (P less than 0.05) at 1 and 2 years posttransplant (116 +/- 27 and 115 +/- 15, respectively) than at 1 month (128 +/- 31) in the recipients, but the mean of the mean values in the normal controls (100 +/- 7) was even lower (P less than 0.05). Mean values of individual timepoints during the profile were significantly lower for 6 of the 14 values in the controls than in the recipients. The mean IVGTT K value of the normal controls (-1.9 +/- 0.4%) was significantly lower than the 1-month and 2-year values of the recipients (-1.5 +/- 0.5% and -1.3 +/- 0.6%, respectively), but the comparison with the 1-year value (-1.6 +/- 0.6%) was not significant. The mean glucose levels at zero minutes and between 120 and 300 min of the OGTTs were significantly lower at both 1 and 2 years than at 1 month in the recipients, and the values in the control group were also significantly lower than in the recipients at 1 month but not at 1 and 2 years.