De novo diabetic nephropathy on renal allografts

Micro-vascular complications of post-transplant diabetes mellitus in renal transplant recipients- an observational study

INTRODUCTION

The incidence of post-transplant diabetes mellitus (PTDM) ranges from 2.5% to 20% in kidney transplant recipients. Diabetic retinopathy (DR), diabetic kidney disease (DKD), and distal symmetric polyneuropathy (DSPN) are the microvascular complications frequently seen in both type 1 and 2 diabetes mellitus (DM). However, the data regarding these complications in patients with PTDM is lacking.

METHOD

A retrospective and prospective observational study of PTDM conducted at a tertiary care hospital from November 2018 to December 2020. 115 kidney transplant recipients who had PTDM of ≥5 years duration were included and analysed.

RESULTS

The mean duration of PTDM was 8.8 ± 3.0 years, and the mean of all available HbA1c values was 7.0 ± 0.9%. while none of the patients had evidence of diabetic retinopathy on direct ophthalmoscopy, 37.4% of patients (n = 43) had DSPN and this was associated with the duration of PTDM and age. The mean estimated glomerular filtration rate (eGFR) was 59.24 ± 21.82 ml/min/1.73m2, and patients had a median proteinuria of 620 mg/day (IQR 1290). Out of 115 patients, 20% of them (n = 23) underwent graft kidney biopsy, and 10 biopsies were diagnosed as de-novo DKD. Patients with biopsy proven DKD had a mean PTDM duration of 143.3 ± 52.4 months; a mean HbA1c level of 7.9 ± 1.3%; a mean eGFR of 44.8 ± 21.8 ml/min; and a median proteinuria of 2653 mg (IQR 2758). An additional analysis of all 23 biopsied patients showed that HbA1c level and degree of proteinuria were significantly associated with de-novo DKD.

CONCLUSION

PTDM in transplant patients had milder microvascular complications than usually expected in Type 1/2 diabetes in non-transplant patients. DR was not strongly associated with DKD in PTDM patients. Furthermore, de-novo DKD development was associated with poor glycaemic control and increased proteinuria.

Post-Transplantation Diabetes Mellitus

Solid organ transplantation (SOT) is an established therapeutic option for chronic disease resulting from end-stage organ dysfunction. Long-term use of immunosuppression is associated with post-transplantation diabetes mellitus (PTDM), placing patients at increased risk of infections, cardiovascular disease and mortality. The incidence rates for PTDM have varied from 10 to 40% between different studies. Diagnostic criteria have evolved over the years, as a greater understating of PTDM has been reached. There are differences in pathophysiology and clinical course of type 2 diabetes and PTDM. Hence, managing this condition can be a challenge for a diabetes physician, as there are several factors to consider when tailoring therapy for post-transplant patients to achieve better glycaemic as well as long-term transplant outcomes. This article is a detailed review of PTDM, examining the pathogenesis, diagnostic criteria and management in light of the current evidence. The therapeutic options are discussed in the context of their safety and potential drug-drug interactions with immunosuppressive agents.

Outcomes of de novo allograft diabetic nephropathy in renal allograft recipients

OBJECTIVES

Despite increased use of diabetogenic immunosuppressive drugs and increased incidence of new-onset diabetes after transplant in renal allograft recipients, there are few case studies on the subject of de novo allograft diabetic nephropathy and interstitial fibrosis/tubular atrophy without specific glomerular changes. We sought to study the outcomes of allograft diabetic nephropathy and interstitial fibrosis/tubular atrophy without specific glomerular changes in patients with new-onset diabetes after transplant.

MATERIALS AND METHODS

We reviewed the case records of all new-onset diabetes after transplant patients who underwent graft biopsy for graft dysfunction from 1992 to 2010. We analyzed the clinical characteristics and outcomes of new-onset diabetes after transplant patients with de novo allograft diabetic nephropathy and interstitial fibrosis/tubular atrophy without specific glomerular changes.

RESULTS

Of the 1989 recipients, 421 patients developed new-onset diabetes after transplant and 26 underwent graft biopsy. Of the 26 patients, 9 had histopathologic evidence of de novo allograft diabetic nephropathy, and 17 had interstitial fibrosis/tubular atrophy without specific glomerular changes. The mean duration from transplant to developing novo allograft diabetic nephropathy was 115.2 months (range, 33-192 mo), and from developing new-onset diabetes after transplant to allograft diabetic nephropathy, was 109.66 months (range, 27-188.4 mo). Of the 9 patients with de novo allograft diabetic nephropathy, 3 died (33.3%), 2 reached end-stage renal disease (22.2%), and 4 remained stable (44.4%). Of the 17 with interstitial fibrosis/tubular atrophy, 2 died (11.7%), 5 developed end-stage renal disease (29.4%), and 10 remained stable on triple immunosuppression and insulin therapy during follow-up (58.8%).

CONCLUSIONS

De novo allograft diabetic nephropathy is a significant cause of graft and patient loss in renal allograft recipients who develop new-onset diabetes after transplant.

Complications associated with new-onset diabetes after kidney transplantation

New-onset diabetes mellitus after kidney transplantation (NODAT) is widely acknowledged to be associated with increased morbidity and mortality, as well as poor quality of life. Clear evidence links the occurrence of NODAT to accelerated progression of some macrovascular and/or microvascular complications. However, the evidence that some complications commonly attributed to diabetes mellitus occur in the context of transplantation lacks robustness. Certain complications are transplantation-specific and prevalent, but others are not frequently observed or documented. For this reason, it is essential that clinicians are aware of the array of potential complications associated with NODAT in kidney allograft recipients. Rather than simply translating evidence from the general population to the high-risk transplant recipient, this Review aims to provide specific guidance on diabetes-related complications in the context of a complex transplantation environment.

Impact of glucose metabolism abnormalities on histopathological changes in kidney transplant protocol biopsies

The impact of post-transplant diabetes (PTDM) on kidney transplant histopathology has been poorly described. We examined the association of glucose metabolism abnormalities on the progression of histopathological changes in serial protocol biopsies. Helsinki University Hospital kidney transplant recipients during 2004-2006 were followed up. Patients with pre-existing diabetes or 2-h oral glucose tolerance test (OGTT) performed at 3 months, and protocol biopsies taken at 0 and 12 months were analyzed (n = 76). Diabetes was defined according to WHO/ADA. Histology was analyzed with chronic allograft damage index (CADI). Altogether 32 patients had pre-existing diabetes. In OGTT at 3 months, four showed PTDM, eight impaired glucose tolerance (IGT), two impaired fasting glucose, and 30 normal glucose tolerance. Patients with impaired glucose metabolism were older (P = 0.005), received grafts from older donors (P = 0.04), and had reduced renal function at 12 months (P = 0.003). In patients with IGT or PTDM, 2-h postload glucose values in OGTT correlated with CADI at 12 months (R = 0.84, P = 0.001) and with the change in CADI score between 0 and 12 months (R = 0.67, P = 0.025). Graft survival was reduced in patients with pre-existing diabetes (P = 0.01). Glucose abnormalities were associated with the progression of histopathological changes, especially in patients with already compromised kidneys, supporting the harmful role of PTDM to the kidney allograft.