Long‐term outcome of islet transplantation on insulin‐dependent diabetes mellitus: An observational cohort study

AIMS/INTRODUCTION: To investigate the long‐term efficacy and safety of islet transplantation (ITx) compared with multiple daily injections (MDI) or continuous subcutaneous insulin infusion (CSII). MATERIALS AND METHODS: Among 619 patients diagnosed as insulin‐dependent diabetes mellitus or type 1 diabetes at Kyoto University, Kyoto, Japan, seven patients were selected as the ITx group and 26 age‐matched patients with no endogenous insulin secretion were selected as the MDI/CSII group. Hemoglobin A1c, aspartate aminotransferase/alanine aminotransferase (AST/ALT) and creatinine were assessed retrospectively at 1, 2, 5 and 10 years for both groups; serum C‐peptide immunoreactivity was assessed for the ITx group. Major clinical events were also assessed. RESULTS: Hemoglobin A1c improvement in ITx was significant at 1 year (8.4% [7.8–9.9%] at baseline to 7.1% [6.3–7.4%] in ITx vs 8.2% [7.4–9.8%] at baseline to 8.1% [7.3–9.5%] in MDI/CSII, P < 0.01 between groups), and was maintained at 2 years (7.4% [6.3–8.2%] vs 8.4% [7.4–9.6%], P = 0.11). The increase of stimulated C‐peptide immunoreactivity was significant at 1 year (0.57 ng/mL [0.26–0.99 ng/mL], P < 0.05 from baseline) and 2 years (0.43 ng/mL [0.19–0.67 ng/mL], P < 0.05), although it became insignificant thereafter. There was no significant difference in AST/ALT or creatinine at 10 years, although a transient AST/ALT elevation was observed in ITx. In regard to clinical events, the occurrence of severe hypoglycemia was 14% vs 31% (relative risk 0.46, P = 0.64), that of infectious disease was 43% vs 12% (relative risk 3.71, P = 0.09) and digestive symptoms was 43% vs 7.7% (relative risk 5.57, P = 0.05) in ITx vs MDI/CSII, respectively. No patient died in either group. CONCLUSIONS: The present findings showed that ITx was considered to contribute to the reduction of hypoglycemia and better glycemic control with tolerable, but attention‐requiring, risks over a period of 10 years compared with MDI/CSII.