#1888 Association between intrapatient variability of serum tacrolimus levels with the development of diabetes in post-kidney transplantation patients
Authors: Carrera Lucino Bahena , Chavez-Mendoza Carlos Adrián , Chico Miguel Eduardo Lopez , Manzo-Arellano Luis Ignacio , Garcia Adan Rodriguez 
Published: May 2024

Abstract

Background and Aims
Kidney transplantation is the most cost-effective renal replacement therapy compared to dialysis. Diabetes is main cause of increased cardiovascular risk and death.
Post-transplant Diabetes Mellitus (PTDM) it refers to presence of diabetes in an environment after kidney transplantation; According to the ADA (American Diabetes Association) criteria, the diagnosis must be made with a tolerance test with 75 grams of oral glucose (Oral glucose tolerance test-OGTT) or the determination of glycosylated hemoglobin 1Ac (Hb1Ac) in a post-transplant period of stability of the immunosuppression dose and without infections.
There are various risk factors for the development of PTDM: hypomagnesemia, glucocorticoids, calcineurin inhibitors (tacrolimus and cyclosporine); hepatitis C virus and cytomegalovirus infections.
In a Mexican kidney transplant recipients in Guadalajara, Andrade SG demonstrated that the incidence of PTDM was 10.1% at 1 year post-transplant. In the Spanish population, Porrini E demonstrated that tacrolimus represents a risk factor for the development of PTDM, increasing the incidence of prediabetes by 33% at 12 months post-transplant.
Several mechanisms have been implicated in the association of calcineurin inhibitor and PTDM: decreased insulin secretion, glucose intolerance, reduced pancreatic beta cell mass, increased islet apoptosis and decreased insulin gene expression.
Studies mention that tacrolimus (FK) is more diabetogenic than cyclosporine (CsA) especially at levels above 20 ng/mL. The DIRECT study (Diabetes Incidence after Renal Transplantation) showed the incidence in 73 kidney transplant patients with CsA (26%) and 96 FK patients (33.6%, p = 0.046). By the other side, Malik RF mentions that FK levels aren´t a risk factor for the development of PTDM.
To demonstrate that the high intrapatient variability of tacrolimus/cyclosporine serum levels correlates with the development of diabetes (PTDM) in kidney transplant recipients at the central military hospital in Mexico City.

Method
Observational, analytical, longitudinal and retrospective study. All kidney transplant recipients from living donors and cadaveric donors from January 2002 to December 2020 were included. FK and CsA were used as maintenance immunosuppression. Serum levels of FK/CsA, Hb1Ac and glucose were measured at months 0, 3, 6, 9 and 12 and intra-patient variability (IPV) of FK/CsA levels was calculated for each patient. The patients were separated into 2 groups, IPV low and IPV high according to the mean the coefficient of variability (CV). The IPV of the calcineurin inhibitor was estimated by calculating the CV in each patient according to the following equation: CV(%)= (SD/mean trough concentration of FK/ CsA)×100. The diagnosis of PTDM followed the criteria of the American Diabetes Association. The Mann Whitney U test was used.

Results
638 kidney transplant recipients were included. The mean age of the recipients was 36.78 (±12.81) years. At the time of kidney transplant, the BMI was 22.67 (±3.90) and 25.76 (±3.99) kg/m² BS at 1 year post-transplant for whole cohort.
At 1 year post-transplant, 72.3% patients were on FK and 27.7% on CsA. Hb1Ac for whole cohort was 4.81 (±0.71)% and 4.84 (±0.77)% at month 0 and 12 post-kidney transplant, respectively. FK and CsA levels were 12.41 (±5.31) and 234.34 (±87.80) ng/mL and 9.13 (±5.3) and 194.38 (±92.44) ng/mL in the PTDM and non-PTDM groups, respectively (p = 0.029). 17.96% of patients developed PTDM. Mean CV of the entire cohort was 33.84 (±20.41)%.
When performing the analysis of the IPV coefficient by subgroups of maintenance immunosuppression used at 1 year post-transplant: the IPV of FK was 43.39 (±18.49)% and 29.99 (±17.56)% in the PTDM and non-PTDM groups respectively, p = 0.000, which shows that patients with a high IPV coefficient of tacrolimus developed more PTDM than those with low variability, student's t-test to compare IPV was 0.03.
The IPV of CsA was 38.61 (±18.76)% and 37.51 (±25.67)% in the PTDM and non-PTDM groups respectively, p = 0.819.

Conclusion
High intrapatient variability of tacrolimus was correlated with the development of PTDM in Mexican kidney transplant recipients.