Validation of diagnostic utility of fasting plasma glucose and HbA1c in stable renal transplant recipients one year after transplantation

Abstract

BackgroundThe use of HbA1c ≥6.5% for diagnosis of diabetes has been challenged for post-transplantation diabetes mellitus (PTDM) also known as new onset diabetes after transplantation (NODAT) due to a low sensitivity early after renal transplantation. PTDM diagnosed with an oral glucose tolerance test (OGTT) is highly predictable for long-term patient mortality. HbA1c was introduced for diagnosis based on the risk of developing diabetic retinopathy. The utility of HbA1c measures versus glucose criteria has not been widely assessed in stable transplant patients but still HbA1c is widely used in this population. The aim of the present analyses was to validate the utility of fasting plasma glucose (FPG) together with HbA1c in diagnosing PTDM in stable renal transplant recipients (RTRs).MethodsOGTT’s were performed one year after transplantation in 494 consecutive RTRs without diabetes. FPG and HbA1c were obtained the same day, before starting the OGTT. Validation was performed using C-statistics and logistic regression analyses.ResultsPTDM was diagnosed in 51 patients (10.3%) by glucose criteria, 38 (74%) patients were diagnosed by FPG ≥7.0 mmol/L [126.1 mg/dl], and 13 (26%) only by 2-h plasma glucose. Six of the latter had HbA1c ≥6.5%. Only seven patients out of the 51 (13.7%) PTDM patients remained undiagnosed when HbA1c ≥6.5% was used together with FPG, and five of these regressed to normal after a median follow-up of 14 months. ROC curves including FPG and HbA1c versus OGTT derived criteria revealed an AUC of 0.858.ConclusionsCombining standard diagnostic FPG and HbA1c criteria captured almost all patients with persistent PTDM in stable RTRs. The combined use of the criteria appears to be an applicable diagnostic strategy for PTDM without the need of an OGTT one year post-transplant.Trial registrationRetrospectively registered.

Management of metabolic alterations in adult kidney transplant recipients: A joint position statement of the Italian Society of Nephrology (SIN), the Italian Society for Organ Transplantation (SITO) and the Italian Diabetes Society (SID)

“…In a retrospective analysis of nearly 500 KTRs without known diabetes who underwent comprehensive assessment of glycaemic status at one year after transplant, including HbA1c, FPG and OGTT, using HbA1c alone (!6.5% or 48 mmol/mol) resulted in a specificity of 97% and sensitivity of 43% [32]. This finding is in line with those of a systematic review and metanalysis showing that HbA1c !…”

High Plasma Branched-Chain Amino Acids Are Associated with Higher Risk of Post-Transplant Diabetes Mellitus in Renal Transplant Recipients

“…Furthermore, it is known that oral glucose tolerance tests (OGTTs) are the gold standard diagnostic tool to diagnose PTDM. Unfortunately, OGTTs were not performed, but recently it has been shown that the combined use of fasting plasma glucose and HbA1c criteria appears to be a diagnostic strategy for PTDM in stable renal transplant recipients [72]. Another limitation of this study is that only 38 subjects developed PTDM during follow-up, which led to a lack of power.…”

Post-transplant Diabetes Mellitus in Kidney Transplant Recipients: A Multicenter Study

“…This multicenter study is likely more generalizable than many prior single-center studies (Supplementary Table 1). 2,3,[9][10][11]13,15,[20][21][36][37][38][39][40][41][42][43][44][45][46][47] Many studies defined PTDM using the 2003 International Consensus Guidelines based on recommendations of the ADA. 18 Some groups also used extended PTDM diagnostic criteria that include administration of antihyperglycemic agents and updated ADA recommendations such as hemoglobin A1c ≥6.5%.…”

“…For the PTDM group, event rates per 1000 patient-years were as follows: dcGF 32 (95% CI: 21-47), aGF 67 (51-88), and all-cause mortality 43 . Event rates for the non-PTDM group were: dcGF 37 (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46), aGF 58 (49-68), and all-cause mortality 28 (22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35). Results were unchanged when considering diabetes treatment type (insulin therapy, oral antihyperglycemics, and diet only) for the PTDM patients.…”