Pre-diabetes and arterial stiffness in uraemic patients

Cardiac arrhythmia and hypoglycaemia in patients receiving haemodialysis with and without diabetes (the CADDY study): protocol for a Danish multicentre cohort study

INTRODUCTION

Patients receiving haemodialysis are at increased risk of arrhythmias and sudden cardiac death, but data on arrhythmia burden and the pathophysiology remain limited. Among potential risk factors, hypoglycaemia is proposed as a possible trigger of lethal arrhythmias. The development of implantable loop recorders (ILR) and continuous glucose monitoring (CGM) enables long-term continuous ECG and glycaemic monitoring. The current article presents the protocol of a study aiming to increase the understanding of arrhythmias and risk factors in patients receiving haemodialysis. The findings will provide a detailed exploration of the burden and nature of arrhythmias in these patients including the potential association between hypoglycaemia and arrhythmias.

METHODS AND ANALYSIS

The study is an investigator-initiated, prospective, multicentre cohort study recruiting 70 patients receiving haemodialysis: 35 with diabetes and 35 without diabetes. Participants are monitored with ILRs and CGM for 18 months follow-up. Data collection further includes a monthly collection of predialysis blood samples and dialysis parameters. The primary outcome is the presence of clinically significant arrhythmias defined as a composite of bradycardia, ventricular tachycardia, or ventricular fibrillation. Secondary outcomes include the characterisation of clinically significant arrhythmias and other arrhythmias, glycaemic characteristics, and mortality. The data analyses include an assessment of the association between arrhythmias and hypoglycaemia and hyperglycaemia, baseline clinical variables, and parameters related to kidney failure and the haemodialysis procedure.

ETHICS AND DISSEMINATION

The study has been approved by the Ethics Committee of the Capital Region of Denmark (H-20069767). The findings will be presented at national and international congresses as well as in international peer-reviewed scientific journals.

TRIAL REGISTRATION NUMBER

NCT04841304.

Use of Glucose-Lowering Agents in Diabetes and CKD

Diabetes is the most common cause of kidney failure worldwide. Patients with diabetes and chronic kidney disease (CKD) are also at markedly higher risk of cardiovascular disease, particularly heart failure (HF), and death. Through the processes of gluconeogenesis and glucose reabsorption, the kidney plays a central role in glucose homeostasis. Insulin resistance is an early alteration observed in CKD, worsened by the frequent presence of hypertension, obesity, and ongoing chronic inflammation, and oxidative stress. Management of diabetes in moderate to severe CKD warrants special consideration because of changes in glucose and insulin homeostasis and altered metabolism of glucose-lowering therapies. Kidney failure and initiation of kidney replacement therapy by dialysis adds to management complexity by further limiting therapeutic options, and predisposing individuals to hypoglycemia and hyperglycemia. Glycemic goals should be individualized, considering CKD severity, presence of macrovascular and microvascular complications, and life expectancy. A general hemoglobin A1c (HbA1c) goal of approximately 7% may be appropriate in earlier stages of CKD, with more relaxed targets often appropriate in later stages. Use of sodium glucose cotransporter2 (SGLT2) inhibitors and glucagon like peptide-1 receptor agonists (GLP-1RAs) meaningfully improves kidney and heart outcomes for patients with diabetes and CKD, irrespective of HbA1c targets, and are now part of guideline-directed medical therapy in this high-risk population. Delivery of optimal care for patients with diabetes and CKD will require collaboration across health care specialties and disciplines.

Arterial Stiffness and Cardiometabolic-Based Chronic Disease: The Kardiovize Study

OBJECTIVE

Arterial stiffness (ArSt) describes a loss of arterial wall elasticity and is an independent predictor of cardiovascular events. A cardiometabolic-based chronic disease model integrates concepts of adiposity-based chronic disease (ABCD), dysglycemia-based chronic disease (DBCD), and cardiovascular disease. We assessed if ABCD and DBCD models detect more people with high ArSt compared with traditional adiposity and dysglycemia classifiers using the cardio-ankle vascular index (CAVI).

METHODS

We evaluated 2070 subjects aged 25 to 64 years from a random population-based sample. Those with type 1 diabetes were excluded. ABCD and DBCD were defined, and ArSt risk was stratified based on the American Association of Clinical Endocrinologists criteria.

RESULTS

The highest prevalence of a high CAVI was in stage 2 ABCD (18.5%) and stage 4 DBCD (31.8%), and the lowest prevalence was in stage 0 ABCD (2.2%). In univariate analysis, stage 2 ABCD and all DBCD stages increased the risk of having a high CAVI compared with traditional classifiers. After adjusting for age and gender, only an inverse association between obesity (body mass index ≥30 kg/m²) and CAVI remained significant. Nevertheless, body mass index was responsible for only 0.3% of CAVI variability.

CONCLUSION

The ABCD and DBCD models showed better performance than traditional classifiers to detect subjects with ArSt; however, the variables were not independently associated with age and gender, which might be explained by the complexity and multifactoriality of the relationship of CAVI with the ABCD and DBCD models, mediated by insulin resistance.

Effect of the Incretin Hormones on the Endocrine Pancreas in End-Stage Renal Disease

CONTEXT

The insulin-stimulating and glucagon-regulating effects of the 2 incretin hormones, glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), contribute to maintain normal glucose homeostasis. Impaired glucose tolerance occurs with high prevalence among patients with end-stage renal disease (ESRD).

OBJECTIVE

To evaluate the effect of the incretin hormones on endocrine pancreatic function in patients with ESRD.

DESIGN AND SETTING

Twelve ESRD patients on chronic hemodialysis and 12 matched healthy controls, all with normal oral glucose tolerance test, were included. On 3 separate days, a 2-hour euglycemic clamp followed by a 2-hour hyperglycemic clamp (3 mM above fasting level) was performed with concomitant infusion of GLP-1 (1 pmol/kg/min), GIP (2 pmol/kg/min), or saline administered in a randomized, double-blinded fashion. A 30% lower infusion rate was used in the ESRD group to obtain comparable incretin hormone plasma levels.

RESULTS

During clamps, comparable plasma glucose and intact incretin hormone concentrations were achieved. The effect of GLP-1 to increase insulin concentrations relative to placebo levels tended to be lower during euglycemia in ESRD and was significantly reduced during hyperglycemia (50 [8-72]%, P = 0.03). Similarly, the effect of GIP relative to placebo levels tended to be lower during euglycemia in ESRD and was significantly reduced during hyperglycemia (34 [13-50]%, P = 0.005). Glucagon was suppressed in both groups, with controls reaching lower concentrations than ESRD patients.

CONCLUSIONS

The effect of incretin hormones to increase insulin release is reduced in ESRD, which, together with elevated glucagon levels, could contribute to the high prevalence of impaired glucose tolerance among ESRD patients.

Mannose-binding lectin genotypes and outcome in end-stage renal disease: a prospective cohort study

Background

Patients with end-stage renal disease (ESRD) have high morbidity and mortality rates, with cardiovascular diseases and infections being the major causes of death. Mannose-binding lectin (MBL) has been suggested to play a protective role in this regard. The aim of this study was to investigate a possible clinical association of MBL genotypes (MBL2) with outcome among patients on dialysis or with a functioning graft.

Methods

A total of 98 patients with ESRD accepted for living-donor renal transplantation or on the waiting list for transplantation were included and prospectively followed for an average of 9 years (range 7.5-9.9). Medical records were evaluated regarding transplantation status, diabetes mellitus, vascular parameters and infections for all the patients. Cox regression models and logistic regression analysis were used for statistical analyses. The cohort was divided into two groups according to the MBL2 genotype (normal A/A versus variant A/O or O/O).

Results

We found no evidence for an association between the MBL2 genotype and all-cause mortality, cardiovascular events or bacterial infections (pneumonia, urinary tract infection, fistula infection or other infections).

Conclusion

In this cohort, the MBL2 genotype did not seem to be associated with any long-term clinical effects in ESRD patients on dialysis or with a functioning graft.

Pretransplant HbA1c and Glucose Metabolism Parameters in Predicting Posttransplant Diabetes Mellitus and Their Course in the First 6 Months After Living-Donor Renal Transplant

OBJECTIVES

Posttransplant diabetes mellitus is a common and serious metabolic complication after renal transplant. Patients with uremia are known to have abnormal glucose metabolism characterized by insulin resistance and defects in insulin secretion, which are ameliorated to some extent with renal replacement therapy and more so with renal transplant. However, the diabetogenicity of calcineurin inhibitors compounds this state of dysglycemia and promotes the development of diabetes in some patients. It is not clear whether pretransplant dysglycemia is a risk factor for posttransplant diabetes mellitus and, if so, which between insulin resistance and pancreatic β-cell dysfunction is a major determinant in predicting posttransplant diabetes mellitus. Here, we examined the roles of the pretransplant oral glucose tolerance test, glycated hemoglobin (HbA1c) levels, and homeostatic model assessment-derived insulin resistance and beta-cell function in the prediction of posttransplant diabetes mellitus and the course of these indexes posttransplant. Our aim was to examine the correlations between these factors and their changes posttransplant with the development of posttransplant diabetes mellitus.

MATERIALS AND METHODS

Pretransplant fasting blood was drawn from patients for plasma glucose, insulin, C-peptide, and HbA1c levels, which was followed by a 2-hour oral glucose tolerance test. After transplant, patients were followed for 6 months to detect posttransplant diabetes mellitus. Serum insulin, C-peptide, and glycated hemoglobin levels were reexamined in patients with posttransplant diabetes mellitus at 1 and 6 months.

RESULTS

Twenty-one patients (29%) developed posttransplant diabetes mellitus. Pretransplant HbA1c was associated with development of posttransplant diabetes mellitus (odds ratio 27.04) on logistic regression. Homeostatic model assessment-derived insulin resistance improved significantly at 6 months posttransplant, whereas beta-cell function remained lower than pretransplant levels in patients with posttransplant diabetes mellitus.

CONCLUSIONS

Pretransplant HbA1c may be used as a predictive marker for posttransplant diabetes mellitus. Insulin resistance but not beta-cell function improves in patients with posttransplant diabetes mellitus at 6 months posttransplant.

Marinobufagenin-induced vascular fibrosis is a likely target for mineralocorticoid antagonists

OBJECTIVE

Endogenous cardiotonic steroids, including marinobufagenin (MBG), stimulate vascular synthesis of collagen. Because mineralocorticoid antagonists competitively antagonize effect of cardiotonic steroids on the Na/K-ATPase, we hypothesized that spironolactone would reverse the profibrotic effects of MBG.

METHODS

Experiment 1: Explants of thoracic aortae and aortic vascular smooth muscle cells from Wistar rats were cultured for 24 h in the presence of vehicle or MBG (100 nmol/l) with or without canrenone (10 μmol/l), an active metabolite of spironolactone. Experiment 2: In 16 patients (56 ± 2 years) with resistant hypertension on a combined (lisinopril/amlodipine/hydrochlorothiazide) therapy, we determined arterial pressure, pulse wave velocity, plasma MBG, and erythrocyte Na/K-ATPase before and 6 months after addition of placebo (n = 8) or spironolactone (50 mg/day; n = 8) to the therapy.

RESULTS

In rat aortic explants and in vascular smooth muscle cells, pretreatment with MBG resulted in a two-fold rise in collagen-1, and a marked reduction in the sensitivity of the aortic rings to the vasorelaxant effect of sodium nitroprusside following endothelin-1-induced constriction (EC50 = 480 ± 67 vs. 23 ± 3 nmol/l in vehicle-treated rings; P < 0.01). Canrenone blocked effects of MBG on collagen synthesis and restored sensitivity of vascular rings to sodium nitroprusside (EC50 = 17 ± 1 nmol/l). Resistant hypertension patients exhibited elevated plasma MBG (0.42 ± 0.07 vs. 0.24 ± 0.03 nmol/l; P = 0.01) and reduced Na/K-ATPase activity (1.9 ± 0.15 vs. 2.8 ± 0.2 μmol Pi/ml per h, P < 0.01) vs. seven healthy individuals. Six-month administration of spironolactone, unlike placebo treatment, was associated with a decrease in pulse wave velocity and arterial pressure, and with restoration of Na/K-ATPase activity in the presence of unchanged MBG levels.

CONCLUSION

MBG-induced vascular fibrosis is a likely target for spironolactone.

High levels of mannose-binding lectin are associated with lower pulse wave velocity in uraemic patients

Background

Uraemia is associated with a highly increased risk of cardiovascular disease. Mannose-binding lectin (MBL) has been shown to be involved in cardiovascular pathophysiology and a protective effect of MBL is suggested. The purpose of the present study was to evaluate a potential impact of MBL on vascular parameters in uraemic patients.

Methods

A cohort of 98 patients with end stage renal disease (ESRD) awaiting kidney transplantation had pulse wave velocity (PWV) and augmentation index (AIX) examined by tonometry and endothelial dependent flow-mediated (FMD) and endothelial independent nitroglycerin-induced (NID) dilatory capacities of the brachial artery measured by ultrasound. An oral glucose tolerance test (OGTT) was performed and serum levels of MBL were measured using Luminex xMAP bead array technology.

Results

The cohort was divided in two groups according to MBL-concentration below or above the median concentration. These groups were comparable regarding age, BMI, and duration of ESRD. PWV was significantly lower in the group with high MBL levels compared to the group with low MBL levels and trends toward better AIX and higher insulin sensitivity (ISI) was also seen in the group with high MBL levels. No difference was seen in FMD and NID.

Conclusions

High levels of MBL are associated with lower PWV and the use of antihypertensive drugs in a cohort of patients with ESRD awaiting kidney transplantation suggesting a beneficial role of high levels of MBL on arterial stiffness in uraemia.

Gastrointestinal factors contribute to glucometabolic disturbances in nondiabetic patients with end-stage renal disease

Nondiabetic patients with end-stage renal disease (ESRD) have disturbed glucose metabolism, the underlying pathophysiology of which is unclear. To help elucidate this, we studied patients with ESRD and either normal or impaired glucose tolerance (10 each NGT or IGT, respectively) and 11 controls using an oral glucose tolerance test and an isoglycemic intravenous glucose infusion on separate days. Plasma glucose, insulin, glucagon, and incretin hormones were measured repeatedly, and gastrointestinal-mediated glucose disposal (GIGD) based on glucose amounts utilized, and incretin effect based on incremental insulin responses, were calculated. The GIGD was significantly reduced in both ESRD groups compared with controls. Incretin effects were 69% (controls), 55% (ESRD with NGT), and 41% (ESRD with IGT), with a significant difference between controls and ESRDs with IGT. Fasting concentrations of glucagon and incretin hormones were significantly increased in patients with ESRD. Glucagon suppression was significantly impaired in both groups with ESRD compared with controls, while the baseline-corrected incretin hormone responses were unaltered between groups. Thus, patients with ESRD had reduced GIGD, a diminished incretin effect in those with IGT, and severe fasting hyperglucagonemia that seemed irrepressible in response to glucose stimuli. These factors may contribute to disturbed glucose metabolism in ESRD.

New-onset diabetes mellitus after kidney transplantation in Denmark

BACKGROUND AND OBJECTIVES

This study aimed to investigate the development of new-onset diabetes mellitus (NODM) in a prospective study of 97 nondiabetic uremic patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Included were 57 kidney recipients (Tx group, age 39 +/- 13 years) and 40 uremic patients remaining on the waiting list for kidney transplantation (uremic controls, age 47 +/- 11 years). All were examined at baseline before possible transplantation and after 12 months. The prevalence of diabetes, prediabetes, insulin sensitivity index (ISI), and insulin secretion index (Isecr) were estimated using an oral glucose tolerance test with measurements of plasma glucose and plasma insulin.

RESULTS

One year after transplantation NODM was present in 14% (8 of 57) compared with 5% (2 of 40) in the uremic control group (P = 0.01). ISI in the Tx group deteriorated from 6.8 +/- 3.9 before transplantation to 4.9 +/- 2.8 at 12 months after transplantation (P = 0.005), and a slight increase in Isecr from 37 +/- 19 to 46 +/- 22 (P = 0.02) was seen. No significant changes occurred in the uremic controls (ISI was 7.9 +/- 5 and 8.5 +/- 5, and Isecr was 31 +/- 17 and 28 +/- 15). Using multivariate ordinal logistic regression, pre-Tx ISI and age predicted NODM (odds ratios: 0.82, P = 0.01 and 1.06, P = 0.02, respectively).

CONCLUSIONS

One year after kidney transplantation, NODM was present in 14% of patients. This was mainly caused by an increase in insulin resistance and was observed despite improvement in insulin secretion.