The diagnosis of posttransplantation diabetes mellitus: meeting the challenges

Vancomycin relieves tacrolimus-induced hyperglycemia by eliminating gut bacterial beta-glucuronidase enzyme activity

Up to 40% of transplant recipients treated long-term with tacrolimus (TAC) develop post-transplant diabetes mellitus (PTDM). TAC is an important risk factor for PTDM, but is also essential for immunosuppression after transplantation. Long-term TAC treatment alters the gut microbiome, but the mechanisms of TAC-induced gut microbiota in the pathogenesis of PTDM are poorly characterized. Here, we showed that vancomycin, an inhibitor of bacterial beta-glucuronidase (GUS), prevents TAC-induced glucose disorder and insulin resistance in mice. Metagenomics shows that GUS-producing bacteria are predominant and flourish in the TAC-induced hyperglycemia mouse model, with upregulation of intestinal GUS activity. Targeted metabolomics analysis revealed that in the presence of high GUS activity, the hydrolysis of bile acid (BAs)-glucuronic conjugates is increased and most BAs are overproduced in the serum and liver, which, in turn, activates the ileal farnesoid X receptor (FXR) and suppresses GLP-1 secretion by L-cells. The GUS inhibitor vancomycin significantly eliminated GUS-producing bacteria and inhibited bacterial GUS activity and BAs levels, thereby enhancing L-cell GLP-1 secretion and preventing hyperglycemia. Our results propose a novel clinical strategy for inhibiting the bacterial GUS enzyme to prevent hyperglycemia without requiring withdrawal of TAC treatment. This strategy exerted its effect through the ileal bile acid-FXR-GLP-1 pathway.

Criteria for prediabetes and posttransplant diabetes mellitus after kidney transplantation: A 2-year diagnostic accuracy study of participants from a randomized controlled trial

Posttransplant diabetes mellitus (PTDM) and prediabetes (impaired glucose tolerance [IGT] and impaired fasting glucose [IFG]) are associated with cardiovascular events. We assessed the diagnostic performance of fasting plasma glucose (FPG) and HbA_1c as alternatives to oral glucose tolerance test (OGTT)-derived 2-hour plasma glucose (2hPG) using sensitivity and specificity in 263 kidney transplant recipients (KTRs) from a clinical trial. Between visits at 6, 12, and 24 months after transplantation, 28%-31% of patients switched glycemic category (normal glucose tolerance [NGT], IGT/IFG, PTDM). Correlations of FPG and HbA_1c against 2hPG were lower at 6 months (r = 0.59 [FPG against 2hPG]; r = 0.45 [HbA_1c against 2hPG]) vs. 24 months (r = 0.73 [FPG against 2hPG]; r = 0.74 [HbA_1c against 2hPG]). Up to 69% of 2hPG-defined PTDM cases were missed by conventional HbA_1c and FPG thresholds. For prediabetes, concordance of FPG and HbA_1c with 2hPG ranged from 6%-9%. In conclusion, in our well-defined randomized trial cohort, one-third of KTRs switched glycemic category over 2 years and although the correlations of FPG and HbA_1c with 2hPG improved with time, their diagnostic concordance was poor for PTDM and, especially, prediabetes. Considering posttransplant metabolic instability, FPG's and HbA_1c 's diagnostic performance, the OGTT remains indispensable to diagnose PTDM and prediabetes after kidney transplantation.

Post-Transplantation Diabetes Mellitus in Pediatric Patients

More than 80% of pediatric solid organ transplant (SOT) recipients now survive into young adulthood and many encounter transplant-related complications. Post-transplantation diabetes mellitus (PTDM), sometimes also referred to as post-transplant diabetes or new onset diabetes after transplant, occurs in 3-20% of pediatric SOT recipients depending upon the organ transplanted, age at transplantation, immunosuppressive regimen, family history, and time elapsed since transplant. To diagnose PTDM, hyperglycemia must persist beyond the initial hospitalization for transplantation when a patient is on stable doses of immunosuppressive medications. Though standard diagnostic criteria used by the American Diabetes Association (ADA) to diagnose diabetes are employed, clinicians need to be aware of the limitations of using these criteria in this unique patient population. Management of PTDM parallels strategies used for type 2 diabetes (T2D), while also carefully considering comorbidities and potential interactions with immunosuppressive medications in these patients. In caring for patients with PTDM, it is important to be familiar with these interactions and comorbidities in order to coordinate care with the transplant team and optimize outcomes for these patients.

Risk Factors for Developing Posttransplant Diabetes After Pediatric Kidney Transplant in a Canadian Tertiary Care Children's Hospital Between 1995 and 2016

BACKGROUND

Posttransplant diabetes mellitus (PTDM) is a serious complication in kidney transplant recipients (KTRs) due to its negative impact on graft and patient survival. Although reported in 3% to 20% of pediatric KTRs, it has not been as well characterized in adults. In this study we describe incidence and risk factors associated with development of PTDM in pediatric KTRs.

METHODS

This work is a retrospective cohort study of nondiabetic pediatric patients, aged 6 months to 19 years, who underwent a first kidney transplant during 1995 to 2016. We estimated the cumulative incidence rate and used multivariable logistic regression to identify the diabetogenic risk factors for PTDM.

RESULTS

A total of 142 KTRs were included in this study. The cumulative incidence of PTDM was 31% and 14.1% in the first and second year posttransplant, respectively. Significant risk factors for PTDM in the first year after transplant included: dysglycemia in the first 8 to 30 days posttransplant (adjusted odds ratio [aOR], 3.02; 95% confidence interval [CI], 1.21 to 7.53; p=0.018) and use of sirolimus in the first 30 days posttransplant (aOR, 5.33; 95% CI, 1.16 to 24.35; p=0.031). No significant association was found with typical diabetogenic factors.

CONCLUSIONS

The incidence of PTDM is high among pediatric KTRs. Independent risk factors associated with PTDM included meeting the criteria for dysglycemia or diabetes and sirolimus use in the first month posttransplant. Typical diabetogenic risk factors for type 2 diabetes were not associated with increased risk. This study provides valuable information for posttransplant medical care and future research.

Incretin based therapies and SGLT-2 inhibitors in kidney transplant recipients with diabetes: A systematic review and meta-analysis

AIMS

We aimed to conduct a systematic review and meta-analysis regarding the use of incretin-based therapies including dipeptidyl peptidase-4 (DPP-4) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists as well as sodium-glucose co-transporter-2 (SGLT2) inhibitorsin persons with posttransplantation diabetes mellitus (PTDM) so as to assess both their efficacy and safety.

METHODS

We searched for publications on Kidney/Renal Transplantation and DPP-4 inhibitors, GLP-1-receptor agonists and SGLT-2 inhibitors and included every study using these antidiabetics. A p-value < 0.05 was considered statistical significant.

RESULTS

Sixteen studies and 310 individuals with a mean age of 55.98 ± 8.81 years were included in the analysis. Participants received DPP-4 inhibitors in 8 studies, SGLT-2 inhibitors in 6 studies and GLP-1 receptor agonists in 2 studies, with a mean follow-up of 22.03 ± 14.95 weeks. Hemoglobin A1c (HbA1c) reduction was demonstrated in 10 studies (mean +/- standard deviation (MD) = - 0.38%, I² = 45%). MD of HbA1c was -0.3741 and -0.4596 mg/dl for DPP-4 inhibitors and SGLT-2 inhibitors respectively. Nine studies demonstrated differences in fasting plasma glucose (FPG) (MD = - 25,76) and 5 studies in post-prandial glucose (PPG) (MD = - 6.61) before and following treatment. Most studies did not show adverse effects on the glomerular filtration rate (GFR) and hepatic function.

CONCLUSIONS

DPP-4 inhibitors and SGLT2 inhibitors appear both efficacious and safe in renal transplant recipients. More high-quality studies are required to guide therapeutic choices for PTDM.

The Degree of Hyperglycemia Excursion in Patients of Kidney Transplantation (KT) or Liver Transplantation (LT) Assessed by Continuous Glucose Monitoring (CGM): Pilot Study

OBJECTIVE

This study used a continuous glucose monitoring system (CGMS) to investigate the glucose profiles and assess the degree of hyperglycemic excursion after kidney or liver transplantation during the early period after operation.

METHODS

Patients to whom a CGMS was attached during a postoperative period of approximately one month after transplantation were included. The CGM data of 31 patients including 24 with kidney transplantation (KT) and seven with liver transplantation (LT) were analyzed.

RESULTS

Hyperglycemia over 126 mg/dL (fasting) or 200 g/dL (postprandial) occurred in 42.1% (8/19) and 16.7% (1/6) of KT and LT patients, respectively, during this early period after transplantation, except for patients with preexisting diabetes (5 KT, 1 LT). The average mean amplitude of glycemic excursion (MAGE) and mean absolute glucose (MAG) levels were 91.18 ± 26.51 vs. 65.66 ± 22.55 (P < 0.05) and 24.62 ± 7.78 vs. 18.18 ± 7.07 (P < 0.05) in KT vs. LT patients, respectively, in patients without preexisting DM or PTDM patients who showed normal glucose levels. Average increase from the lowest level to the peak glucose value was higher in KT patients than LT patients (P < 0.05). Conclusions. The transplanted organ also needs to be considered as an important factor affecting glucose control and the occurrence of more severe glucose excursions in patients who receive transplantation although immunosuppression agents are well-known important factors; however, our study was limited to the early posttransplantation period. Further studies involving CGM follow-up at regular intervals based on the time since transplantation are needed.

Effect of Conversion to CTLA4Ig on Tacrolimus-Induced Diabetic Rats

BACKGROUND

The effect of conversion to cytotoxic T lymphocyte-associated protein 4 immunoglobulin (CTLA4Ig) treatment on tacrolimus (TAC)-induced renal dysfunction is well known, but its effect on TAC-induced diabetes mellitus (DM) is still undetermined. In the present study, we tested the diabetogenicity of CTLA4Ig and evaluated the effect of conversion to CTLA4Ig treatment on TAC-induced diabetic rats.

METHODS

We tested diabetogenicity of CTLA4Ig by escalating doses (0.25, 0.5, 1, 2, and 4 mg/kg weekly) for 4 weeks. In the conversion study, we administered TAC (1.5 mg/kg) for 3 weeks and confirmed TAC-induced DM by intraperitoneal glucose tolerance test. Thereafter, TAC administration was continued, withdrawn, or replaced by CTLA4Ig treatment (1 or 2 mg/kg) for additional 3 weeks. The effect of CTLA4Ig on TAC-induced DM in vivo and in vitro was evaluated by assessing pancreatic islet function, histopathology, oxidative stress, apoptosis, and macrophage infiltration.

RESULTS

Intraperitoneal glucose tolerance test in the CTLA4Ig groups did not differ from the control group. In addition, plasma insulin level, glucose-induced insulin secretion, and islet viability were not different between the CTLA4Ig and control groups. In the conversion study, TAC withdrawal ameliorated pancreatic islet dysfunction compared with the TAC group, and conversion to CTLA4Ig further improved pancreatic islet function compared with the TAC withdrawal group. TAC-induced oxidative stress, apoptotic cell death, and infiltration of macrophages decreased with TAC withdrawal, and CTLA4Ig conversion further reduced those values. In the in vitro study, CTLA4Ig decreased TAC-induced pancreatic islet cell death and reactive oxygen species production.

CONCLUSIONS

CTLA4Ig was not diabetogenic, and conversion to CTLA4Ig reduced TAC-induced pancreatic islet injury.

Higher Pretransplantation Hemoglobin A1c Is Associated With Greater Risk of Posttransplant Diabetes Mellitus

Introduction

Posttransplantation diabetes mellitus (PTDM) is a common complication among kidney transplant recipients and is associated with a higher risk of cardiovascular events and poorer graft and patient survival. The association of pretransplantation hemoglobin A1c (HbA1c) with PTDM remains unclear. Identifying recipients at greatest risk for PTDM may help guide monitoring and treatment strategies to prevent or delay the onset of PTDM.

Methods

We analyzed data from 1499 nondiabetic primary kidney transplant recipients with available pretransplantation HbA1c values in the United States Renal Data System (USRDS) from 2005 to 2011. Recipients with pretransplantation diabetes diagnosis or HbA1c ≥ 6.5% were excluded. We assessed the association of pretransplantation HbA1c with PTDM using Cox proportional hazards models. Pretransplantation HbA1c level as a continuous variable was modeled using restricted cubic splines with knots at the 25th, 50th, and 75th percentiles. Based on results from this model, pretransplantation HbA1c was further modeled using a linear spline with a single knot at 5.4%.

Results

A total of 395 recipients (26.4%) developed PTDM over a median follow-up of 1.8 years. Pretransplantation HbA1c was not significantly associated with risk of PTDM below 5.4%, whereas each 1% higher HbA1c above 5.4% was associated with an adjusted hazard ratio of 1.84 (95% confidence interval = 1.28, 2.66; P for change in slope = 0.04).

Discussion

Higher pretransplantation HbA1c above 5.4% is independently associated with greater risk of PTDM among kidney transplant recipients. A continuous relationship between pretransplantation HbA1c and risk of PTDM suggests that increased risk starts at HbA1c levels well below current thresholds for prediabetes.

A Prospective Study of Renal Transplant Recipients: A Fall in Insulin Secretion Underpins Dysglycemia After Renal Transplantation

Background

Dysglycemia (encompassing impaired glucose tolerance and diabetes mellitus) arising after renal transplantation is common and confers a significant cardiovascular mortality risk. Nonetheless, the pathophysiology of posttransplant dysglycemia is not well described. The aim of this study was to prospectively and comprehensively assess glucose handling in renal transplant recipients from before to 12 months after transplantation to determine the underpinning pathophysiology.

Materials and Methods

Intravenous and oral glucose tolerance testing was conducted before and at 3 and 12 months posttransplantation. An intravenous glucose tolerance test was also performed on day 7 posttransplantation. We followed up 16 transplant recipients for 3 months and 14 recipients for 12 months. Insulin secretion, resistance and a disposition index (DI (IV)), a measure of β cell responsiveness in the context of prevailing insulin resistance, were also determined.

Results

At 12 months, 50% of renal transplant recipients had dysglycemia. Dysglycemia was associated with a dramatic fall in DI (IV) and this loss in β cell function was evident as early as 3 months posttransplantation (23.5 pretransplant; 6.4 at 3 months and 12.2 at 12 months posttransplant). Differences in the β cell response to oral glucose challenge were evident pretransplant in those destined to develop dysglycemia posttransplant (2-hour blood glucose level 5.6 mmol/L versus 6.8 mmol/L; P < 0.01).

Conclusions

Dysglycemia after renal transplantation is common, and the loss of insulin secretion is a major contributor. Subclinical differences in glucose handling are evident pretransplant in those destined to develop dysglycemia potentially heralding a susceptible β cell which under the stressors associated with transplantation fails.