Renal replacement therapy, a solid-organ transplant is a resolute treatment modality in patients with end-stage renal disease. However, it is often associated with impaired glucose tolerance or diabetes mellitus [1], cardiovascular complications, increased susceptibility to infections, and declined renal allograft function [2]. Some common causes of graft dysfunction are rejection, emergence of new or recurring renal conditions, infections, and drug toxicity [3]. New-onset diabetes after transplantation (NODAT) is a well-established outcome of organ transplantation, leading to elevated risk of infection and mortality [4,5]. There are various determinants of NODAT including the family history, age, sedentary lifestyle and prediabetes status [6-8]. Furthermore, the usage of immunosuppressive drugs like calcineurin inhibitors (tacrolimus and cyclosporine) can also be considered as significant precursors to NODAT [9,10]. Several studies indicate that the occurrence of new-onset diabetes after transplantation (NODAT) varies between 7% and 30% within the first year following kidney transplantation. Additionally, approximately 76.5% of organ recipients experience NODAT within the initial 3 months. However, after 6 months, the rate of diabetes in these patients is nearly equivalent to those without a transplant [11,12]. According to literature from India, the incidence rates of new-onset diabetes after transplantation (NODAT) range from 16% to 30%, with the highest cumulative incidence occurring within the first year following the transplant [13-15]. For the reduction of cardiovascular complications and improvement of the outcome of renal transplantation, it is of great interest to know precisely the risk factors that contribute to NODAT development. The timely identification of high blood sugar levels is crucial as it allows for prompt optimization of inpatient plasma glucose, which has a positive impact on the long-term survival of both the patient and the transplanted organ. The objective of management is to achieve sufficient control of blood sugar levels in order to minimize the complications associated with hyperglycaemia. If lifestyle changes and adjustments to immunosuppressant medications are not enough to manage hyperglycaemia effectively, the initiation of pharmacotherapy becomes necessary [16]. In light of the above context, the present study aimed at evaluating the prevalence and the determinants which might be associated with the development of NODAT. This study also assessed different treatment modalities and their respective response in patients with NODAT.

Study design This was a retrospective study conducted in the Renal Transplant Unit, SCB Medical college and Hospital, Odisha, from March 2012 to November 2020, including the renal allograft recipients who came for follow-up care at the hospital. Eligibility criteria The patients in age group of >18 years and either sex, recipient of renal allograft were included in this study. The patients <18 years of age at the time of transplant and the follow-up duration of <6 months were excluded from the study. Data collection The demographic characteristics of the patients like age, gender, body mass index (BMI), etiologies of primary renal disease, history of dialysis, type of renal transplantation (living or deceased), degrees of related living donors, pharmacologic therapy (induction and maintenance therapy), family history of diabetes and follow-ups were retrieved from the patient’s medical charts. A detailed clinical history along with pretransplant parameters, fasting plasma glucose (FPG), and impaired fasting glucose (IFG), post a week of transplantation was evaluated. The serum creatinine levels at baseline and at the last visit of follow-up were assessed. The acute rejection episodes and its respective treatments were noted. Endpoints The primary endpoint was to assess the prevalence and determinants of NODAT. Definitions The diagnosis of New-Onset Diabetes After Transplantation (NODAT) was determined using the diagnostic criteria for diabetes proposed by an international consensus meeting on post-transplantation diabetes mellitus in 2003. This included the presence of diabetes symptoms such as excessive urination, excessive thirst, or unexplained weight loss, along with a random blood glucose level of 200mg/dl or higher, or a fasting plasma glucose (FPG) level of 126mg/dl or higher, or a second-hour plasma glucose level of 200mg/dl or higher during an oral glucose tolerance test (OGTT). Furthermore, NODAT was considered to have developed when patients were prescribed glucose-lowering medications (insulin and/or oral hypoglycemic agents) for more than one month, as prescribed by the nephrologist or endocrinologist, at any time during the study. The diagnosis was always confirmed by measuring fasting blood glucose (FBG) and/or HbA1c levels in these patients. Due to the impracticality of conducting OGTTs in a large transplant program, they were not routinely used in our unit. Since this study was a retrospective analysis, patients with transient hyperglycemia were not classified as having NODAT and were included in the non-NODAT group. In other words, only patients who were still diabetic and being treated with antidiabetic medications on the day of the study were included in the NODAT group. HbA1c was not initially used as a diagnostic criterion within the first three months after transplantation. However, it was later incorporated as a diagnostic criterion in combination with elevated FBG levels. The time of onset of NODAT was recorded. Immunosuppression All patients received induction therapy as part of their treatment. The immunosuppressive regimen consisted of either rabbit antithymocyte globulin (ATG) or IL-2 receptor monoclonal antibody (basiliximab), depending on the specific induction therapy. Methylprednisolone was administered intraoperatively at a dosage of 500mg, followed by a gradual reduction to a daily oral prednisone dosage of 30mg within one week, 10mg at one month, and 5mg at the 12th week after transplantation. Mycophenolate-mofetil (MMF) or mycophenolate sodium (MMY) was prescribed at a dosage of 2 × 1000mg/d or 2 × 720mg/d. Calcineurin inhibitors (CNI) (either tacrolimus or cyclosporine A) were initiated 12 hours before the surgery. Cyclosporine A (CsA) was started at a daily dosage of 8mg/kg, while tacrolimus was administered at a daily dosage of 0.12mg/kg, with subsequent adjustments based on total blood levels. The target CsA levels at 3 months post-transplantation ranged from 150 to 250ng/ml, which were then gradually tapered to 100-150ng/ml by 1 year. The target tacrolimus levels in the first year after transplantation were 8-11ng/ml, followed by a tapering to 5-8ng/ml for the next 3 years, and below 5ng/ml thereafter. The standard maintenance therapy, also known as the immunosuppressive protocol, primarily consisted of triple therapy. This regimen included the administration of steroids, a calcineurin inhibitor (either cyclosporine or tacrolimus), and MMF/MMY (mycophenolate-mofetil or mycophenolate sodium). Statistical analysis The statistical analysis was done using SPSS version 22. Descriptive data are expressed as mean and standard deviation (SD) and numbers (No.), and percentages (%).

Demographic characteristics of NODAT and non-NODAT groups A total of 161 patients were enrolled in this study. The proportion of male population was higher than the female population in both the groups, (95.6% vs. 4.3% and 91.3% vs. 8.6%). Among these patients, three were deceased donor renal transplants and 158 were living renal transplants including spousal donors. Ten of 23 patients (43.0%) developed NODAT in less than 1 year after transplantation (early NODAT). The mean age in the NODAT group was 36.2 (9.3) years and 34.7 (7.8) years in non NODAT group. There was no significant difference in mean age between two groups (P=0.414), however a significant number of patients in NODAT group(NODAT-39.1% and non-NODAT-15.9%) belonged to the age group of >45 years (P=0.018). significantly higher number of patients in NODAT group had family history of diabetes melitus(p value=0.045).Male to female ratio in NODAT and non NODAT group was 22:1 and 10.5:1 respectively. A trend towards significance was observed in difference in mean BMI of the two groups (P=0.058).Pre-operative FBS was significantly higher in NODAT group than nonNODAT group(P<0.003).There was no significant difference in the number of HCV seropositive patients between two groups. All the patients in this study were on haemodialysis, except for one patient with pre-emptive renal transplantation. The demographic characteristics are summarized in Table 1. Biochemical characteristics of NODAT and non-NODAT groups In NODAT group, 56.5% of patients received basiliximab, whereas 43.5% of patients received ATG. In non-NODAT group, 57.2% of patients received ATG whereas 42.8% of patients received basiliximab. The trough tacrolimus at the time of discharge was higher in NODAT group than non-NODAT group (12.3 vs. 9.8, P<0.001), with a significant difference. It was observed that the type of CNI used in patients were not associated with increased prevalence of NODAT (p=0.694), however the trough tacrolimus level at discharge was significantly higher in patients developing NODAT (p value<0.001). The mTOR inhibitors were used in 8.6% of patients in NODAT group and 12.3% of patients in non-NODAT group, however with no significance difference. The biochemical parameters are summarized in Table 2. Table 1: Demographic characteristics in NODAT and non-NODAT group Parameter NODAT (n=23) Non-NODAT (n=138) P value Age (years), mean (SD) 36.2 (9.3) 34.7 (7.8) 0.414 Age group (years) >45 9 (39.1) 22 (15.9) 0.018 Sex Male Female 22 (95.6) 1 (4.3) 126 (91.3) 12 (8.6) 0.315 Male: Female ratio 22:1 10:5:1 - Family history of diabetes 8 (34.8) 15 (10.9) 0.045 BMI (kg/m2), mean (SD) 25.0 (4.7) 23.7 (2.8) 0.058 HCV seropositive 2 (8.6) 12 (8.6) 1.000 Pre-operative FBS (mg/dL), mean (SD) 96.5 (11.5) 90.2 (8.8) 0.003 Data given as n (%), unless otherwise specified. BMI, body mass index; FBS, fasting blood sugar; HCV, hepatitis C positive Table 2: Biochemical characteristics in NODAT and non-NODAT group Parameter NODAT (n=23) Non-NODAT (n=138) P value CNI Cyclosporine Tacrolimus 2 (8.6) 21 (91.3) 14 (10.1) 124 (89.9) 0.694 CNI levels Tacrolimus levels (ng/mL), mean (SD) 12.3 (1.4) 9.8 (1.0) <0.001 Induction used ATG Basiliximab 10 (43.5) 13 (56.5) 79 (57.2) 59 (42.8) 0.260 mTOR inhibitor 2 (8.6) 17 (12.3) 0.202 Data given as n (%), unless otherwise specified. ATG, anti-thymocyte globulin; CNI, calcineurin inhibitors; mTOR, mammalian target of rapamycin

NODAT is now recognized as a significant factor impacting both short-term and long-term outcomes for patients and grafts. The reported incidence of NODAT in the literature has shown considerable variability, ranging from 2% to 53% [17]. In Indian studies, the prevalence of NODAT also varies widely, with rates reported as 16.7% in a study by Sharma et al., 19.12% in an observation by Prakash et al., and as high as 54.5% in a study by Bora et al [13-15]. In our study, the prevalence of NODAT was found to be 14.3%, which was lower than the prevalence reported in other Indian studies. Within the first year of renal transplant, 56.5% (n = 13) of patients developed NODAT, and the prevalence increased over time. This finding aligns with the results of Choudhury et al., who reported that early NODAT (within one year after transplant) occurred in 55.8% of cases, while late NODAT (more than one year after transplant) was observed in 44.2% of cases [18]. Risk factors associated with the emergence of new-onset diabetes after transplantation (NODAT) in renal transplant patients can be categorized into two main groups: non-modifiable risk factors and modifiable risk factors. Non-modifiable risk factors include race, with a higher incidence observed in blacks and Hispanics, advanced age, male recipient, positive family history of diabetes, the presence of specific HLA phenotypes such as HLA A30, B27, and B42, increased HLA mismatches, receiving a kidney from a deceased donor, having polycystic kidney disease, and impaired fasting plasma glucose (FPG) or oral glucose tolerance test (OGTT) results prior to transplantation. On the other hand, modifiable risk factors include the type of immunosuppressive therapy, obesity, male gender of the donor, pre-transplant hypertriglyceridemia, hepatitis C virus (HCV) infection, and cytomegalovirus (CMV) disease [1,19]. This data was consistent with this study, in which the family history, age, BMI, pre-transplant FBS, and immunosuppressant dose were came across as possible risk factors for NODAT. Advanced age, a positive family history of diabetes, elevated plasma glucose levels prior to transplantation, and obesity are individual factors that are linked to the onset of diabetes following renal transplantation [20]. Several studies have identified older age as a risk factor for new-onset diabetes after transplantation (NODAT) [21,22]. A study by Ghisdal L et al. demonstrated that patients undergoing kidney transplantation who are aged 45-59 years experienced a significant 90% increase in relative risk, while patients older than 60 years had an even higher increase of 160% in relative risk, in comparison to patients aged 18-44 years [23]. These findings were consistent with the results achieved in this study, where the majority of the patients (31.0%) belonged to the age group of >45 years. Indian studies by Prakash et al. and Bora et.al showed that the family history of diabetes mellitus can be a potential risk factor for NODAT [13,14]. This insight was also observed in this study, where the family history of diabetes was present in significantly higher number of cases in NODAT group than nonNODAT group. Recent evidence indicates that, similar to diabetes in the general population, having a positive family history of diabetes among first-degree relatives is a significant risk factor for the development of new-onset diabetes after transplantation (NODAT) in transplant recipients as well [1,24]. In this study a trend towards significance was observed in difference in mean BMI of the two groups (P=0.058).A meta-analysis of 55 studies involving 15,458 kidney transplantation cases done by S Chang et al suggested that BMI is an independent risk factor for NODAT. Significantly higher level of pretransplant fasting blood sugar was found in patients in NODAT group than the patients in nonNODAT group. Similar finding was observed by Choudhury et al. Patients with prediabetic conditions such as FBS levels between 90 and 100 mg/dl need to be monitored closely post-transplant and advised on life style modifications to avoid weight gain [18]. Immunosuppressive drugs alone contribute to a substantial 74% risk of developing new-onset diabetes after transplantation (NODAT) [25]. Tacrolimus is reported to have a higher potential to induce diabetes compared to cyclosporine, although findings vary across different studies [7,15,26,28,29]. In the DIRECT trial, the incidence of NODAT was significantly higher in patients treated with tacrolimus (16.8%) compared to those on cyclosporine (8.9%) [26]. However, the relationship between calcineurin inhibitors (CNIs) and the development of NODAT is complex, with multiple confounding variables reported [27-29]. A dose reduction of tacrolimus by 33% has been shown to enhance insulin secretion without altering therapeutic levels of tacrolimus (within the range of 5-10 ng/ml), suggesting that the diabetogenic effect of tacrolimus is dose-dependent [30]. In this study, a significant difference in the incidence of NODAT between patients receiving tacrolimus and those receiving cyclosporine was not observed. However, the trough level of tacrolimus was significantly higher in patients who developed NODAT. In this study, it was observed that both HCV seropositive and seronegative patients had an equal risk of developing new-onset diabetes after transplantation (NODAT), which contrasts with the findings reported by Bloom et al. and Sharma et al [29]. Successful pre-transplant treatment of HCV infection, with achievement of sustained virological response, was found to attenuate incidence of NODAT(1).nIn our study all the 14 HCV seropositive patients (2 in NODAT group and 12 in non-NODAT group) were treated with DAAs and sustained viral response was achieved before transplantation. The use of sirolimus, an mTOR inhibitor, has indeed been linked to an increased risk of new-onset diabetes after transplantation (NODAT). In a study by Sulanc et al., the combination of tacrolimus and sirolimus therapy was associated with a higher incidence of NODAT compared to tacrolimus therapy alone [6]. However, in this study, there was no significant difference in the use of mTOR inhibitors between the two groups. A plausible sample size, adequate follow-up duration, assessment of pre-transplant risk factors and immunosuppressive regimen are some of the strengths of this study. However, there were some limitations of this study; this was a retrospective study ,the additional risk factors like genetic factors and cause-and-effect of risk factors were not assessed. Hence a randomized trial with large sample size can provide better assessment of the risk factors associated with NODAT.

The incidence of NODAT in this study was 14.3%.Age (>45 years), BMI, family history, FBS, and trough tacrolimus levels in patients can be important determinants for predicting NODAT. Some of these risk factors are quite modifiable and their correction could prevent development of such grave complications in renal transplant recipients.

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