Role of glycated hemoglobin in the screening and diagnosis of posttransplantation diabetes mellitus after renal transplantation: A diagnostic accuracy study

Abstract

Background: The role of glycated hemoglobin (A1C) in the screening and diagnosis of posttransplantation diabetes mellitus (PTDM) is still not entirely understood. We evaluated the use of A1C test in renal transplant recipients at four months after transplantation.

Methods: A total of 122 out of 274 patients without previous diabetes that underwent kidney transplantation were enrolled. ROC curve was used to analyze the performance of A1C to diagnose PTDM considering OGTT as the reference standard.

Results: OGTT identified 32 (26.2%) patients with PTDM, whereas A1C≥6.5% (48 mmol/mol) identified only 16 patients. A1C showed moderate accuracy to detect PTDM in the ROC curve [AUC 0.832 (95% CI 0.740-0.924, p<0.001)]. A1C of 5.8% (40 mmol/mol) was the equilibrium point (sensitivity 75% and specificity 72.2%) and A1C≥6.2% (44 mmol/mol) showed high specificity of 93.3%.

Conclusions: A1C≥6.5% (48 mmol/mol) is not enough to be used alone in the diagnosis of PTDM. The combined use of A1C cut-off points of ≤5.8% (40 mmol/mol) and ≥6.2% (44 mmol/mol) would reduce the number of OGTT by 85%. The use of an algorithm with A1C test in combination with FPG and/or 2h-PG proved to be the most efficient strategy to diagnose or rule out PTDM.

Keywords: A1C; Diagnostic accuracy; Glycated hemoglobin; PTDM; Posttransplantation diabetes mellitus; Renal transplantation.