Insulin secretory patterns and blood glucose homeostasis after islet allotransplantation in IDDM patients: comparison with segmental- or whole-pancreas transplanted patients through a long term longitudinal study

IDDM patients undergoing islet, segmental pancreas or whole pancreas allotr ansplantation were studied at regular intervals after surgery (3-6 months, 1, 2, 3 and 4 years) to evaluate glycometabolic control (24 h metabolic pro file, OGTT) and serum free insulin response to insulinogenic stimuli (argin ine, IVGTT). Patients received the same immunosuppressive therapy, based on cyclosporin, steroids and azathioprine. Islet transplanted patients showed : 1) an early peak of insulin secretion after arginine, that was maintained up to 4 years; 2) an early, but low peak of insulin secretion after IVGTT, which was lost at 3 years, despite evidence that islets were still functio ning (insulin independence with normal HbA1c levels); 3) a diabetic-like re sponse to OGTT at 3 months, which improved at 2 years (IGT response); 4) fa sting euglycemia with mild and reversible post-prandial hyperglycemia durin g the 24 h metabolic profile, which was maintained for up to 2 years. Insul in secretory patterns of islet transplanted patients were similar to segmen tal pancreas transplanted patients, and lower than whole pancreas transplan ted patients. The reduced beta cell mass transplanted and the functional de nervation of the transplanted islets seem to be the major determinants of t his behaviour.