Efficacy of continuous glucose monitoring in people living with diabetes and end stage kidney disease on dialysis: a systematic review

BACKGROUND

Patients with diabetes on dialysis experience wide variations in glucose levels and an increased risk of hypoglycaemia. Due to the inaccuracies of HbA1c in dialysis patients, JBDS-IP and KDIGO recommend the use of continuous glucose monitoring (CGM). We conducted a systematic review to examine the current evidence for CGM use and its impact on clinical outcomes in patients with diabetes on dialysis.

METHODS

A search of MEDLINE(R) ALL, Ovid Emcare, Journals@Ovid Full Text and Embase databases were conducted. Clinical or observational trials in adults with Type 1(T1D) or Type 2 (T2D) diabetes on dialysis and CGM intervention reporting on glycaemic outcomes were included.

RESULTS

Of the 936 citations identified, 49 duplicates were removed. 887 citations were screened by title and abstract. 9 full texts were reviewed and a further 7 excluded due to duplications or failure to meet to selection criteria. Data was extracted for 2 studies, both prospective before-and-after interventional studies with no control group. Joubert et al. (2015) showed results for 15 participants with T1D. Mean CGM glucose level decreased from 8.37mmol/L at baseline to 7.7mmol/L at the end of the CGM period (p < 0.05) while HbA1c decreased from 6.9 to 6.5% (p < 0.05) during the same period. Mean CGM was lower on dialysis days (7.68mmol/L vs. 7.8mmol/L, p < 0.05). Képénékian et al. (2014) reported on data from 29 T2D patients. Following a 3 month CGM-adapted insulin regimen, HbA1c decreased from 8.4% at baseline to 7.6% (p < 0.01) by the end of study. Mean CGM values decreased from 9.9mmol/L to 8.9mmol/L (p = 0.05) and the frequency of glucose values > 10mmol/L decreased from 41 to 30% (p < 0.05), without a significant increase in hypoglycaemia frequency. Both studies were deemed to be of 'good' quality.

CONCLUSION

Evidence demonstrating the benefits of CGM in patients with diabetes receiving dialysis is lacking. There is a need for well-designed randomised controlled trials to ascertain the benefits of this technology in this patient group.

TRAIL REGISTRATION

PROSPERO registration number: CRD42023371635, https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=371635 .

Diabetes mellitus in dialysis and renal transplantation

Diabetes mellitus is the commonest cause of end-stage kidney failure worldwide and is a proven and significant risk factor for the development of cardiovascular disease. Renal impairment has a significant impact on the physiology of glucose homeostasis as it reduces tissue sensitivity to insulin and reduces insulin clearance. Renal replacement therapy itself affects glucose control: peritoneal dialysis may induce hyperglycaemia due to glucose-rich dialysate and haemodialysis often causes hypoglycaemia due to the relatively low concentration of glucose in the dialysate. Autonomic neuropathy which is common in chronic kidney disease (CKD) and diabetes increases the risk for asymptomatic hypoglycaemia. Pharmacological options for improving glycaemic control are limited due to alterations to drug metabolism. Impaired glucose tolerance and diabetes are also common in the post-kidney-transplant setting and increase the risk of graft failure and mortality. This review seeks to summarise the literature and tackle the intricacies of glycaemic management in patients with CKD who are either on maintenance haemodialysis or have received a kidney transplant. It outlines changes to glycaemic targets, monitoring of glycaemic control, the use of oral hypoglycaemic agents, the management of severe hyperglycaemia in dialysis and kidney transplantation patients.

Management of diabetes mellitus in dialysis patients: Obstacles and challenges

BACKGROUND AND AIMS

Diabetic kidney disease (DKD) is a major health issue that is associated with an increased risk of morbidity and mortality. The treatment of DKD is challenging given changes in blood glucose homeostasis, unclear accuracy of glucose metrics, and altered kinetics of the blood glucose-lowering medications. There is uncertainty surrounding the optimal glycemic target in this population although recent epidemiologic data suggest that HbA1c ranges of 6-8%, as well as 7-9%, are associated with increased survival rates among diabetic dialysis patients. Furthermore, the treatment of diabetes in patients maintained on dialysis is challenging, and many blood glucose-lowering medications are renally metabolized and excreted hence requiring dose adjustment or avoidance in dialysis patients.

METHOD

ology: PubMed, Google Scholar, and Medline were searched for all literature discussing the management of diabetes in dialysis patients.

RESULTS

The literature was discussed under many subheadings providing the latest evidence in the treatment of diabetes in dialysis patients.

CONCLUSION

The management of diabetes in dialysis is very complex requiring a multi-disciplinary team involving endocrinologists and nephrologists to achieve targets and reduce morbidity and mortality.

Diabetes mellitus in chronic kidney disease: Biomarkers beyond HbA1c to estimate glycemic control and diabetes-dependent morbidity and mortality

Diabetes mellitus (DM) is the leading cause of chronic kidney disease (CKD). Optimal glycemic control contributes to improved outcomes in patients with DM, particularly for microvascular damage, but blood glucose levels are too variable to provide an accurate assessment and instead markers averaging long-term glycemic load are used. The most established glycemic biomarker of long-term glycemic control is HbA1c. Nevertheless, HbA1c has pitfalls that limit its accuracy to estimate glycemic control, including the presence of altered red blood cell survival, hemoglobin glycation and suboptimal performance of HbA1c assays. Alternative methods to evaluate glycemic control in patients with DM include glycated albumin, fructosamine, 1-5 anhydroglucitol, continuous glucose measurement, self-monitoring of blood glucose and random blood glucose concentration measurements. Accordingly, our aim was to review the advantages and pitfalls of these methods in the context of CKD.

Glycemic Monitoring and Management in Advanced Chronic Kidney Disease

Glucose and insulin metabolism in patients with diabetes are profoundly altered by advanced chronic kidney disease (CKD). Risk of hypoglycemia is increased by failure of kidney gluconeogenesis, impaired insulin clearance by the kidney, defective insulin degradation due to uremia, increased erythrocyte glucose uptake during hemodialysis, impaired counterregulatory hormone responses (cortisol, growth hormone), nutritional deprivation, and variability of exposure to oral antihyperglycemic agents and exogenous insulin. Patients with end-stage kidney disease frequently experience wide glycemic excursions, with common occurrences of both hypoglycemia and hyperglycemia. Assessment of glycemia by glycated hemoglobin (HbA1c) is hampered by a variety of CKD-associated conditions that can bias the measure either to the low or high range. Alternative glycemic biomarkers, such as glycated albumin or fructosamine, are not fully validated. Therefore, HbA1c remains the preferred glycemic biomarker despite its limitations. Based on observational data for associations with mortality and risks of hypoglycemia with intensive glycemic control regimens in advanced CKD, an HbA1c range of 7% to 8% appears to be the most favorable. Emerging data on the use of continuous glucose monitoring in this population suggest promise for more precise monitoring and treatment adjustments to permit fine-tuning of glycemic management in patients with diabetes and advanced CKD.

Is the management of diabetes different in dialysis patients?

Diabetes is highly and increasingly prevalent in the dialysis population and negatively impacts both quality and quantity of life. Nevertheless, the best approach to these patients is still debatable. The question of whether the management of diabetes should be different in dialysis patients does not have a clear yes or no answer but is divided into too many sub-issues that should be carefully considered. In this review, lifestyle, cardiovascular risk, and hyperglycemia management are explored, emphasizing the possible pros and cons of a similar approach to diabetes in dialysis patients compared to the general population.

Determinant Effects of Average Fasting Plasma Glucose on Mortality in Diabetic End-Stage Renal Disease Patients on Maintenance Hemodialysis

Introduction

Diabetic kidney disease is an increasingly frequent cause of end-stage renal disease. However, mixed results were shown between glycated hemoglobin and mortality.

Methods

We used the average fasting plasma glucose (FPG) levels to predict mortality rates in long-term hemodialysis patients. We enrolled 46,332 hemodialysis patients with diabetes mellitus, who were registered in the Taiwan Renal Registry Data System between January 2005 and December 2012. The patients were stratified based on the quartiles of average FPG levels measured for the first (1-year FPG) and third years (3-year FPG) of hemodialysis. Survival analysis was conducted via multivariable Cox regression.

Results

After the first year of hemodialysis, the mean FPG levels were 103.5 ± 14.5, 144.7 ± 11.5, 189.6 ± 15.2, and 280.8 ± 1.2 mg/dl for the first, second, third, and fourth quartile, respectively. The Kaplan-Meier curve showed an incremental reduction in the survival as FPG levels increased (P < 0.0001). In the Cox regression model, the adjusted hazard ratios were 1.15 (95% CI: 1.10–1.20), 1.30 (95% CI: 1.25–1.36), and 1.45 (95% CI: 1.39–1.51) for the pairwise comparisons between the first quartile and the second, third, and fourth quartile, respectively. Similar trends were observed by 3-year FPG. Patients whose FPG levels increased had a 22% increased risk (95% CI: 1.16–1.29) for all-cause mortality compared with patients whose FPG levels decreased.

Discussion

Our results suggest that the average FPG levels are useful predictors of all-cause mortality in dialysis patients. In addition, an increasing trend in average FPG levels indicates poor survival.

What is the Role of HbA1c in Diabetic Hemodialysis Patients?

The definition of a good glycemic control in patients with diabetes mellitus on hemodialysis is far from settled. In the general population, hemoglobin A1c is highly correlated with the average glycemia of the last 8-12 weeks. However, in hemodialysis patients, the correlation of hbA1c with glycemia is weaker as it also reflects changes in hemoglobin characteristics and red blood cells half-life. As expected, studies show that the association between HbA1c and outcomes in these patients differ from the general population. Therefore, the value of HbA1c in the treatment of hemodialysis patients has been questioned. Guidelines are generally cautious in their recommendations about possible targets of HbA1c in this population. Indeed, the risk of not treating hyperglycemia should be weighed against the particularly high risk of precipitating hypoglycemia in dialysis patients. In this review, a critical analysis of the current role of HbA1c in the care of hemodialysis patients is presented.

Updates on the management of diabetes in dialysis patients

Diabetes mellitus is the leading cause of end-stage renal disease (ESRD) in the U.S. and many countries globally. The role of improved glycemic control in ameliorating the exceedingly high mortality risk of diabetic dialysis patients is unclear. The treatment of diabetes in ESRD patients is challenging, given changes in glucose homeostasis, the unclear accuracy of glycemic control metrics, and the altered pharmacokinetics of glucose-lowering drugs by kidney dysfunction, the uremic milieu, and dialysis therapy. Up to one-third of diabetic dialysis patients may experience spontaneous resolution of hyperglycemia with hemoglobin A1c (HbA1c) levels <6%, a phenomenon known as "Burnt-Out Diabetes," which remains with unclear biologic plausibility and undetermined clinical implications. Conventional methods of glycemic control assessment are confounded by the laboratory abnormalities and comorbidities associated with ESRD. Similar to more recent approaches in the general population, there is concern that glucose normalization may be harmful in ESRD patients. There is uncertainty surrounding the optimal glycemic target in this population, although recent epidemiologic data suggest that HbA1c ranges of 6% to 8%, as well as 7% to 9%, are associated with increased survival rates among diabetic dialysis patients. Lastly, many glucose-lowering drugs and their active metabolites are renally metabolized and excreted, and hence, require dose adjustment or avoidance in dialysis patients.

Glycemic control in diabetic dialysis patients and the burnt-out diabetes phenomenon

Diabetes mellitus (DM) is the most common cause of end-stage kidney disease and a major risk of morbidity and mortality. It is not clear whether medical management of DM has any significant beneficial effect on clinical outcomes at the end-stage of diabetic nephropathy with full-blown micro- and macro-angiopathic complications. Both loss of kidney function and dialysis treatment interfere with glucose homeostasis and confound glycemic control. Given the unique nature of uremic milieu and dialysis therapy related alterations, there have been some debates about reliance on the conventional measures of glycemic control, in particular the clinical relevance of hemoglobin A1c and its recommended target range of <7 % in diabetic dialysis patients. Moreover, a so-called burnt-out diabetes phenomenon has been described, in that many diabetic dialysis patients experience frequent hypoglycemic episodes prompting cessation of their anti-diabetic therapies transiently or even permanently. By reviewing the recent literature we argue that the use of A1c for management of diabetic dialysis patients should be encouraged if appropriate target ranges specific for these patients (e.g. 6 to 8 %) are used. We also argue that "burnt-out diabetes" is a true biologic phenomenon and highly prevalent in dialysis patients with established history and end-stage diabetic nephropathy and explore the role of protein-energy wasting to this end. Similarly, the J- or U-shaped associations between A1c or blood glucose concentrations and mortality are likely biologically plausible phenomena that should be taken into consideration in the management of diabetic dialysis patients to avoid hypoglycemia and its fatal consequences in diabetic dialysis patients.

Glycemic control and burnt-out diabetes in ESRD

Treatment of early diabetes mellitus, the most common cause of chronic kidney disease (CKD), may prevent or slow the progression of diabetic nephropathy and lower mortality and the incidence of cardiovascular disease in the general diabetic population and in patients with early stages of CKD. It is unclear whether glycemic control in patients with advanced CKD, including those with end-stage renal disease (ESRD) who undergo maintenance dialysis treatment is beneficial. Aside from the uncertain benefits of treatment in ESRD, hypoglycemic interventions in this population are also complicated by the complex changes in glucose homeostasis related to decreased kidney function and to dialytic therapies, occasionally leading to spontaneous resolution of hyperglycemia and normalization of hemoglobin A1c levels, a condition which might be termed "burnt-out diabetes." Further difficulties in ESRD are posed by the complicated pharmacokinetics of antidiabetic medications and the serious flaws in our available diagnostic tools used for monitoring long-term glycemic control. We review the physiology and pathophysiology of glucose homeostasis in advanced CKD and ESRD, the available antidiabetic medications and their specifics related to kidney function, and the diagnostic tools used to monitor the severity of hyperglycemia and the therapeutic effects of available treatments, along with their deficiencies in ESRD. We also review the concept of burnt-out diabetes and summarize the findings of studies that examined outcomes related to glycemic control in diabetic ESRD patients, and emphasize areas in need of further research.

Glycemic control and the risk of death in 1,484 patients receiving maintenance hemodialysis

BACKGROUND

It is controversial whether tighter glycemic control is associated with better clinical outcomes in people with kidney failure. We aim to determine whether worse glycemic control, measured using serum glucose and hemoglobin A(1c) (HbA(1c)) levels, is independently associated with higher mortality in patients undergoing maintenance hemodialysis.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

1,484 patients starting maintenance hemodialysis therapy in Alberta, Canada, between 2001 and 2007.

PREDICTOR

Serum glucose and HbA(1c) levels.

OUTCOME

All-cause mortality.

MEASUREMENTS

Monthly casual glucose levels from specimens drawn immediately before the first dialysis treatment were averaged over 3 months before and after hemodialysis therapy initiation. Similarly, monthly HbA(1c) values in patients with or at risk of diabetes were averaged.

RESULTS

Overall, median age was 66 years, 41% were women, 75% were white, and 55% had diabetes. All-cause mortality during 8 years (median, 1.5 years) was 43%; it was 49% in those with diabetes. There was no relation between average glucose level and mortality in unadjusted analysis (HR, 1.00 per 18 mg/dL [1 mmol/L]; P = 0.4) or after adjustment for confounders (HR, 0.98 per 18 mg/dL; 95% CI, 0.96-1.01; P = 0.2). Higher HbA(1c) level was not associated with mortality when analyzed in the unadjusted analysis (HR, 1.01 per 1% HbA(1c); P = 0.9) or after adjustment for confounders (HR, 0.98 per 1% HbA1c; 95% CI, 0.88-1.08; P = 0.7). Results were similar when HbA(1c) values were divided into prespecified categories (adjusted P > 0.6 for trend). Markers of malnutrition-inflammation (albumin, hemoglobin, and white blood cell values) or the presence of diabetes did not influence the relation between glycemic control and death (all P for interaction > 0.2).

LIMITATIONS

Registry data; casual serum glucose measurements; HbA(1c) values available for only a subset of participants.

CONCLUSIONS

Higher casual glucose and HbA(1c) levels were not associated with mortality in maintenance hemodialysis patients with or without diabetes. This may have implications for recommended glycemic targets, quality indicators, and how best to assess glycemic control in this high-risk population.

Burnt-out diabetes: impact of chronic kidney disease progression on the natural course of diabetes mellitus

Many individuals with diabetic nephropathy, the leading cause of chronic kidney disease (CKD) in the United States, progress to stage 5 of CKD and undergo maintenance dialysis treatment. Recent data indicate that in up to one third of diabetic dialysis patients with a presumptive diagnosis of diabetic nephropathy, glycemic control improves spontaneously with the progression of CKD, loss of residual renal function, and the initiation of dialysis therapy, leading to normal-to-low hemoglobin A1c (<6%) and glucose levels, requiring cessation of insulin or other anti-diabetic medications. Potential contributors to this so-called "burnt-out diabetes" include decreased renal and hepatic insulin clearance, a decline in renal gluconeogenesis, deficient catecholamine release, diminished food intake (because of anorexia or diabetic gastroparesis), protein-energy wasting (with resultant loss of weight and body fat), and the hypoglycemic effects of dialysis treatment. Although the concept of "burnt-out diabetes" appears in sharp contradistinction to the natural history of diabetes mellitus, studying this condition and its potential causes and consequences, including the role of genetic factors, may lead to a better understanding of the pathophysiology of metabolic syndrome and diabetes mellitus in the CKD population and in many other individuals with chronic disease states associated with wasting syndrome that can confound the natural history of diabetes.

Glycosylated haemoglobin in uraemia

Glycosylated haemoglobin (GHb) was measured in 71 patients with stable chronic renal failure by the thiobarbituric acid (TBA) reaction and by agar gel electrophoresis. Nineteen patients were diabetic. Of the non-diabetics, 22 were treated conservatively (including 8 children), 15 by maintenance haemodialysis, and 15 by continuous ambulatory peritoneal dialysis. GHb measured by both methods correlated with postprandial blood glucose levels. There was a significant discrepancy between the two methods only in patients with serum urea concentrations greater than 30 mmol/l, mean +/- SD, (6.8 +/- 2.6% vs 8.2 +/- 2.5% for TBA and electrophoresis, respectively). This difference, delta GHb, correlated with serum urea, serum creatinine, and serum bicarbonate, but after logistic regression of results from all 71 patients only serum urea was associated with delta GHb. Lower haemoglobin and GHb and high fetal haemoglobin concentrations in the haemodialysis group suggested increased haemolysis in these patients. Measurement of GHb by the TBA method and by agar gel electrophoresis remain useful indicators of hyperglycaemia in patients with mild, stable chronic renal failure.