Objectives: Posttransplant diabetes mellitus is a common and serious metabolic complication after renal transplant. Patients with uremia are known to have abnormal glucose metabolism characterized by insulin resistance and defects in insulin secretion, which are ameliorated to some extent with renal replacement therapy and more so with renal transplant. However, the diabetogenicity of calcineurin inhibitors compounds this state of dysglycemia and promotes the development of diabetes in some patients. It is not clear whether pretransplant dysglycemia is a risk factor for posttransplant diabetes mellitus and, if so, which between insulin resistance and pancreatic β-cell dysfunction is a major determinant in predicting posttransplant diabetes mellitus. Here, we examined the roles of the pretransplant oral glucose tolerance test, glycated hemoglobin (HbA1c) levels, and homeostatic model assessment-derived insulin resistance and beta-cell function in the prediction of posttransplant diabetes mellitus and the course of these indexes posttransplant. Our aim was to examine the correlations between these factors and their changes posttransplant with the development of posttransplant diabetes mellitus.
Materials and methods: Pretransplant fasting blood was drawn from patients for plasma glucose, insulin, C-peptide, and HbA1c levels, which was followed by a 2-hour oral glucose tolerance test. After transplant, patients were followed for 6 months to detect posttransplant diabetes mellitus. Serum insulin, C-peptide, and glycated hemoglobin levels were reexamined in patients with posttransplant diabetes mellitus at 1 and 6 months.
Results: Twenty-one patients (29%) developed posttransplant diabetes mellitus. Pretransplant HbA1c was associated with development of posttransplant diabetes mellitus (odds ratio 27.04) on logistic regression. Homeostatic model assessment-derived insulin resistance improved significantly at 6 months posttransplant, whereas beta-cell function remained lower than pretransplant levels in patients with posttransplant diabetes mellitus.
Conclusions: Pretransplant HbA1c may be used as a predictive marker for posttransplant diabetes mellitus. Insulin resistance but not beta-cell function improves in patients with posttransplant diabetes mellitus at 6 months posttransplant.