Predictive factors of posttransplant glucose intolerance in Japanese patients with type 1 diabetes after pancreas transplantation

Pancreas transplantation (PTx) has been performed worldwide for patients with type 1 diabetes accompanied with end-stage renal disease or uncontrollable glycemic fluctuation. Nevertheless, risk factors of posttransplant glucose intolerance, which is responsible for progress of diabetic complications, remains unclear, especially in cases without pancreatic graft function loss. Therefore, this study was conducted to search for predictive factors of future glucose tolerance in PTx recipients without pancreatic graft function loss. Subjects were selected from among 41 Japanese patients with type 1 diabetes who received PTx between 2000 and 2016 in Osaka University Hospital, and 24 subjects free from rejections and thromboses were analyzed. Several examinations to evaluate insulin secretion and insulin sensitivity within 6 months after transplantation (initial examination) were performed. Glucose tolerance was evaluated by 120-minute post-load plasma glucose level during 75-g oral glucose tolerance tests (OGTT), referred to as PGOGTT120, at the initial examination and between 1 year and 2 years posttransplantation (maintenance period). The initial examination factors that were correlated with PGOGTT120 in the maintenance period were PGOGTT120 [r = 0.52 (p = 0.01)], insulinogenic index [r = -0.65 (p < 0.01)], and the ratio of incremental area under the curve of insulin to that of plasma glucose (iAUCR) calculated from data of OGTT [r = -0.65 (p < 0.01)]. Insulinogenic index [beta = -0.28 (p = 0.02)] and iAUCR [beta = -0.29 (p = 0.02)] were still significantly correlated with PGOGTT120 in the maintenance period after adjustment for PGOGTT120 at the initial examination. In conclusion, insulinogenic index and iAUCR from OGTT performed in the early posttransplantation period were predictive factors of future glucose intolerance.