Indicators for blood glucose control in diabetics with end-stage chronic renal disease: GHb vs. glycated albumin (GA)

Clinical application guidelines for blood glucose monitoring in China (2022 edition)

Glucose monitoring is an important component of diabetes management. The Chinese Diabetes Society (CDS) has been producing evidence-based guidelines on the optimal use of glucose monitoring since 2011. In recent years, new technologies in glucose monitoring and more clinical evidence, especially those derived from Chinese populations, have emerged. In this context, the CDS organised experts to revise the Clinical application guidelines for blood glucose monitoring in China in 2021. In this guideline, we focus on four methods of glucose monitoring that are commonly used in clinical practice, including capillary glucose monitoring, glycated haemoglobin A1c, glycated albumin, and continuous glucose monitoring. We describe the definitions and technical characteristics of these methods, the factor that may interfere with the measurement, the advantages and caveats in clinical practice, the interpretation of glucose metrics, and the relevant supporting evidence. The recommendations for the use of these methods are also provided. The various methods of glucose monitoring have their strengths and limitations and cannot be replaced by one another. We hope that these guidelines could aid in the optimal application of common methods of glucose monitoring in clinical practice for better diabetes care.

Recent Updates and Advances in the Use of Glycated Albumin for the Diagnosis and Monitoring of Diabetes and Renal, Cerebro- and Cardio-Metabolic Diseases

Diabetes mellitus is a heterogeneous and dysmetabolic chronic disease in which the laboratory plays a fundamental role, from diagnosis to monitoring therapy and studying complications. Early diagnosis and good glycemic control should start as early as possible to delay and prevent metabolic and cardio-vascular complications secondary to this disease. Glycated hemoglobin is currently used as the reference parameter. The accuracy of the glycated hemoglobin dosage may be compromised in subjects suffering from chronic renal failure and terminal nephropathy, affected by the reduction in the survival of erythrocytes, with consequent decrease in the time available for glucose to attach to the hemoglobin. In the presence of these renal comorbidities as well as hemoglobinopathies and pregnancy, glycated hemoglobin is not reliable. In such conditions, dosage of glycated albumin can help. Glycated albumin is not only useful for short-term diagnosis and monitoring but predicts the risk of diabetes, even in the presence of euglycemia. This protein is modified in subjects who do not yet have a glycemic alteration but, as a predictive factor, heralds the risk of diabetic disease. This review summarizes the importance of glycated albumin as a biomarker for predicting and stratifying the cardiovascular risk linked to multiorgan metabolic alterations.

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.

Glycated albumin versus hemoglobin A1c and mortality in diabetic hemodialysis patients: a cohort study

Background

For glycemic control in diabetic patients on dialysis it was unclear what level of glycated albumin (GA) was associated with the lowest mortality and GA's utility. Accordingly, we examined the difference in association between GA and hemoglobin A1c (HbA1c) with 1-year mortality in a cohort of the Japanese Society for Dialysis Therapy.

Methods

We examined 84 282 patients with prevalent diabetes who were on maintenance hemodialysis (HD) (female 30.3%; mean age 67.3 ± 11.2 years; mean dialysis vintage 6.4 ± 4.5 years). Of them, 22 441 had both GA and HbA1c. We followed these for a year, 2013-14, using Cox regression to calculate adjusted hazard ratios (HRs) and 95% confidence limits for 1-year mortality after adjusting for potential confounders such as baseline age, sex, smoking and diabetes type.

Results

One-year mortality was lowest in diabetic HD patients who had GA levels of 15.6-18.2% and HbA1c levels of 5.8-6.3%. The associations were linear or J-shaped for GA and U-shaped for HbA1c. Adjusted HRs were significantly higher in patients with GA <12.5% and GA ≥22.9%. This trend flattened in elderly patients, those with higher hemoglobin or those with prior cardiovascular disease. In addition, the C-statistics, Harrell's C and category-free net reclassification improvement to predict 1-year mortality were better when GA was added to the model than when HbA1c was added.

Conclusions

There was a linear or J-shaped association between GA and 1-year mortality, with the lowest mortality at GA 15.6-18.2%. Furthermore, our analyses suggest the potential superiority of GA over HbA1c in predicting mortality.

Inverse association of fat mass, but not lean mass, with glycated albumin in hemodialysis patients with or without diabetes mellitus

Background: Glycated albumin (GA), which is independent of anemia and/or use of erythropoiesis-stimulating agents, might provide a more precise measure than glycated hemoglobin (HbA1c) in hemodialysis patients. The present study examines whether body composition is associated with GA besides glycemic control in hemodialysis patients.

Methods: This study included 90 hemodialysis patients with diabetes mellitus (DM) and 86 hemodialysis patients without DM. We examined blood parameters after an overnight fast and body fat and lean mass using dual X-ray absorptiometry 21–24 h after completing the dialysis session.

Results: The mean body mass index (BMI) was 22.0 kg/m². BMI and truncal fat mass were significantly higher, and total fat mass tended to be higher in hemodialysis patients with DM than in those without DM. GA exhibited inverse correlations with BMI, total lean mass, total fat mass, and truncal fat mass in hemodialysis patients with and without DM; however, there was a lack of correlation with total lean mass in patients without DM. In multiple regression analysis including total fat mass and total lean mass simultaneously as independent variables, total fat mass (with DM: β = –0.322, p = .006) (without DM: β = –0.391, p < .001), but not total lean mass, in addition to log fasting plasma glucose, emerged as an independent factor associated with GA in hemodialysis patients with and without DM. When total fat mass was replaced with truncal fat mass (with DM: β = –0.311, p = .007) (without DM: β = –0.396, p < .001), the association remained significant and independent with GA in both patient groups.

Conclusions: Higher total fat mass, particularly truncal fat mass, might be associated with lower GA levels, beside glycemic control, in hemodialysis patients with or without DM.

Glycemic control and survival in peritoneal dialysis patients with diabetes: A 2-year nationwide cohort study

For glycemic control in patients with diabetes on peritoneal dialysis (PD), the level of glycated albumin (GA) associated with mortality is unclear. Accordingly, we examined the difference in the association of GA and glycated hemoglobin (HbA1c) with 2-year mortality in a Japanese Society for Dialysis Therapy cohort. We examined 1601 patients with prevalent diabetes who were on PD. Of these, 1282 had HbA1c (HbA1c cohort) and 725 had GA (GA cohort) measured. We followed them for 2 years from 2013 to 2015 and used Cox regression to calculate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for 2-year mortality after adjusting for potential confounders in each cohort. No significant association was found between HbA1c levels and all-cause death HRs before and after adjustment for confounders in the HbA1c cohort. In contrast, the adjusted all-cause death HRs and 95% CIs for GAs < 12.0%, 12.0–13.9%, 16.0–17.9%, 18.0–19.9%, 20.0–21.9%, and ≥22.0%, compared with 14.0–15.9% (reference), were 1.56 (0.32–7.45), 1.24 (0.32–4.83), 1.32 (0.36–4.77), 2.02 (0.54–7.53), 4.36 (1.10–17.0), and 4.10 (1.20–14.0), respectively. In the GA cohort, GA ≥ 20.0% was significantly associated with a higher death HR compared with the reference GA. Thus, GA ≥ 20.0% appears to be associated with a decrease in survival in diabetic patients on PD. There were no associations between HbA1c levels and 2-year mortality in PD patients.

The clinical usefulness of glycated albumin in patients with diabetes and chronic kidney disease: Progress and challenges

Prolonged hyperglycemia leads to a non-enzymatic glycation of proteins, and produces Amadori products, such as glycated albumin (GA) and glycated hemoglobin (HbA1c). The utility of HbA1c in the setting of chronic kidney disease (CKD) may be problematic since altered lifespan of red blood cells, use of iron and/or erythropoietin therapy, uremia and so on. Therefore, as an alternative marker, GA has been suggested as a more reliable and sensitive glycemic index in patients with CKD. In addition to the mean plasma glucose concentration, GA also reflects postprandial plasma glucose and glycemic excursion. Besides, with a half-life of approximately 2-3 weeks, GA may reflect the status of blood glucose more rapidly than HbA1c. GA is also an early precursor of advanced glycation end products (AGEs), which cause alterations in various cellular proteins and organelles. Thus, high GA levels may correlate with adverse outcomes of patients with CKD. In this review, the clinical usefulness of GA was discussed, including a comparison of GA with HbA1c, the utility and limitations of GA as a glycemic index, its potential role in pathogenesis of diabetic nephropathy and the correlations between GA levels and outcomes, specifically in patients with diabetes and CKD.

Glycated Albumin Versus HbA1c in the Evaluation of Glycemic Control in Patients With Diabetes and CKD

INTRODUCTION

It is inaccurate to assess blood glucose with glycated hemoglobin (HbA1c) in patients with diabetes and chronic kidney disease (CKD), and whether glycated albumin (GA) is better than HbA1c in these patients remains unclear.

METHODS

We searched PubMed, Embase, Web of Science, Scopus, the Cochrane Library, and MEDLINE to July 2017 for studies that investigated the correlation between GA or HbA1c and the average glucose levels (AG) relevant to this theme. Statistical analysis was performed using RevMan5.3 and Stata12.0. The outcome was the correlation coefficient between GA or HbA1c and AG. For the first time, we made a comparison of GA and HbA1c in different CKD stages.

RESULTS

A total of 24 studies with 3928 patients were included. Early stages of CKD refer to CKD stage 1 to 3. Advanced CKD refer to CKD stage 4 and 5 including patients receiving dialysis. The meta-analysis suggested that in early stages of CKD, the pooled R between GA and AG was 0.61 (95% CI = 0.49-0.73) and 0.71 (95% CI = 0.55-0.87) for HbA1c (P > 0.05). In advanced CKD patients, the pooled R between GA and AG was 0.57 (95% CI = 0.52-0.62), and 0.49 (95% CI = 0.45-0.52) for HbA1c (P = 0.0001).

CONCLUSION

GA is superior to HbA1c in assessing blood glucose control in diabetes patients with advanced CKD.

Can glycated hemoglobin act as a reliable glycemic indicator in patients with diabetic chronic kidney disease? evidence from the Northeast of Thailand

Background: Chronic kidney diseases (CKD) is a common microvascular complication in patients with diabetes mellitus (DM) which requires adequate glycemic control. Glycated hemoglobin (HbA1c) is a conventional biomarker to estimate glycemic status, but its role in diabetic CKD patients is unclear. Therefore, this study aimed to determine whether patients with high HbA1c are associated to develop diabetic CKD.Methods: Data were obtained from a clinical registry of diabetic patients who were treated in a district hospital in the Northeast of Thailand. CKD was defined according to the estimated glomerular filtration rate (eGFR<60mL/min/1.73m2). Anthropometric and biochemical measurements of the patient were taken by review of medical records. Multiple logistic regression analysis was used to determine the likelihood of the association between HbA1c and CKD.Results: Among 4,050 participants, 1,027 (25.3%) developed diabetic CKD. Older age (adjusted odds ratio (AOR): 4.88, 95% confidence interval (CI): 3.71–6.42, p<0.05), female (AOR: 1.38, 95% CI: 1.05–1.73, p<0.05), and hypertension (AOR: 1.52, 95% CI: 1.21–1.91, p<0.05) were found as the risk factors of diabetic CKD. However, patients with high HbA1c (>6.5%) were negatively associated with diabetic CKD (AOR: 0.66, 95% CI: 0.51–0.86, p<0.05).Conclusion: This study found patients with higher HbA1c level were not associated with diabetic CKD. Therefore, using the conventional cut-off values of HbA1c in diabetic CKD patients may be problematic in the clinical settings. Enhanced detection of glycemic status in patients with diabetic CKD is warranted to improve the outcome.

Serum albumin-adjusted glycated albumin as a better indicator of glycemic control in Type 2 diabetes mellitus patients with short duration of hemodialysis

AIMS

Serum albumin-adjusted glycated albumin (adjusted GA) is reportedly a better predictor of mortality than GA in patients with Type 2 diabetes mellitus (T2DM) on hemodialysis (HD). We compared how accurately GA and adjusted GA reflected glycemic control in these patients.

METHODS

We enrolled 31 patients with T2DM on HD. They were divided into two groups according to duration of HD: ≤6months (short HD group, N=16) and >6months (long HD group, N=15). GA or adjusted GA and parameters of glycemic control obtained by continuous glucose monitoring were measured, and the correlations between these were analyzed.

RESULTS

GA and adjusted GA were significantly correlated with mean glucose levels (r=0.400, P=0.025 and r=0.508, P=0.0037) in all patients. Similar results were obtained in the long HD group (GA: r=0.554, P=0.032; adjusted GA: r=0.604, P=0.017). However, in the short HD group, adjusted GA (r=0.502, P=0.047) but not GA (r=0.340, P=0.20) was significantly correlated with mean glucose levels.

CONCLUSIONS

Adjusted GA may be a better indicator than GA for evaluating glycemic control in T2DM patients with short duration of HD.

Abundance matters: role of albumin in diabetes, a proteomics perspective

INTRODUCTION

Human serum albumin (HSA) is a multifaceted protein with vital physiological functions. It is the most abundant plasma protein with inherent capability to bind to diverse ligands, and thus susceptible to various post-translational modifications (PTMs) which alter its structure and functions. One such PTM is glycation, a non-enzymatic reaction between reducing sugar and protein leading to formation of heterogeneous advanced glycation end products (AGEs). Glycated albumin (GA) concentration increases significantly in diabetes and is implicated in development of secondary complications. Areas covered: In this review, we discuss in depth, formation of GA and its consequences, approaches used for characterization and quantification of GA, milestones in GA proteomics, clinical relevance of GA as a biomarker, significance of maintaining abundant levels of albumin and future perspectives. Expert commentary: Elevated GA levels are associated with development of insulin resistance as well as secondary complications, in healthy and diabetic individuals respectively. Mass spectrometry (MS) based approaches aid in precise characterization and quantification of GA including early and advanced glycated peptides, which can be useful in prediction of the disease status. Thus GA has evolved to be one of the best candidates in the pursuit of diagnostic markers for prediction of prediabetes and diabetic complications.

Systematic Literature Review of DPP-4 Inhibitors in Patients with Type 2 Diabetes Mellitus and Renal Impairment

INTRODUCTION

Dipeptidyl peptidase-4 (DPP-4) inhibitors are widely used in the management of patients with type 2 diabetes mellitus (T2DM) and renal impairment (RI). A systematic literature review was performed to compare the efficacy and safety of DPP-4 inhibitors in patients with T2DM and RI.

METHODS

We searched EMBASE, MEDLINE, and the Cochrane Central Register of Controlled Trials (cut-off, June 2015) to identify ≥12-week, randomized, placebo-controlled trials on DPP-4 inhibitors in ≥50 patients with T2DM and RI. Outcomes of interest included change in glycated hemoglobin (HbA1c), overall safety, and incidence of hypoglycemic events (HEs).

RESULTS

Seven trials of ≤52-54 weeks duration were retrieved, which included one study each on vildagliptin, saxagliptin, and sitagliptin, two on linagliptin, and the remaining two were extension studies of vildagliptin and saxagliptin. Majority of patients were on insulin at baseline (53-86%), except in the sitagliptin study, where approximately 11% received insulin during the placebo-controlled phase. After 52 weeks, vildagliptin and saxagliptin reduced HbA1c levels by 0.6-0.7% (baseline 7.8-8.4%) versus placebo in the overall population. HbA1c reductions were similar at weeks 12 and 52. In the 12-week, placebo-controlled phase, sitagliptin and linagliptin reduced mean HbA1c by approximately 0.4% (baseline 7.7-8.1%) versus placebo. Rates of HEs with DPP-4 inhibitors were not significantly different versus placebo in any study. Rates of adverse events (AEs) and changes involving renal function were similar in the active- and placebo-treated groups.

CONCLUSION

These results suggest that DPP-4 inhibitors have the potential to improve glycemic control in patients with RI without increasing the risk of HEs or overall AEs.

FUNDING

Novartis Pharma AG.

Serum albumin-adjusted glycated albumin is a better predictor of mortality in diabetic patients with end-stage renal disease on hemodialysis

AIMS

Glycated albumin (GA) is a marker for monitoring glycemic control in diabetic patients with end-stage renal disease (ESRD). We evaluated whether serum albumin-adjusted GA (adjusted GA) could predict mortality in diabetic patients with ESRD on hemodialysis.

METHODS

Seventy-eight patients with type 2 diabetes treated with regular hemodialysis were enrolled and followed up for 5-years. The adjusted GA was calculated from the regression formula and mean GA. The cut-off values for GA and adjusted GA that predicted mortality risk were determined using receiver operating characteristic curve analysis.

RESULTS

During the follow-up period (median: 36months), 15 patients died. In the Kaplan-Meier analysis, there were no significant differences in the 5-year cumulative survival rate (58.3% [GA ≥19.8%] vs. 88.6% [GA <19.8%], P=0.075). Conversely, this rate was significantly higher in patients with adjusted GA <21.2% than adjusted GA ≥21.2% (86.4 vs. 49.5%, P=0.0068). After adjustment for other confounders, adjusted GA ≥21.2% was an independent predictor for mortality (hazard ratio 3.76, 95% confidence interval 1.12-17.44, P=0.031), but GA ≥19.8% was not (hazard ratio 2.63, 95% confidence interval 0.65-17.69, P=0.19).

CONCLUSIONS

Adjusted GA is a better predictor of mortality than GA in diabetic patients with ESRD on hemodialysis.

Changes of the glycemic control and therapeutic regimen for diabetes mellitus in the Japanese patients on hemodialysis

OBJECTIVES/METHODS

Diabetes mellitus (DM) has become important with regard to mortality in hemodialysis (HD) patients, so it is necessary to optimize the treatment of these patients. We examined the changes in glycemic control and therapeutic regimen, including insulin and oral hypoglycemic agent (OHA) and the diet/exercise in the HD patients.

RESULTS

Although DM was observed in 42 (32.6%) of the 129 (male/female 89/40) patients, there was a male predominance, with 35 DM patients being male (83.3%). The therapeutic regimens of DM patients were as follows: insulin was used in 13, OHA in 20, and diet/exercise in nine patients. The DM patients, who had not used insulin, included five patients receiving OHA (25.0%) and diet/exercise in five patients (55.6%). Nineteen of 20 OHA patients used a dipeptidyl peptidase-IV inhibitor. Although the postprandial blood glucose (PBG) in insulin was 191 ± 89 (the mean ± standard deviation [SD]) mg/dL, that in OHA group was 140 ± 36 mg/dL. The mean and the SD of the PBG were larger in insulin than in OHA group. The body mass index (BMI) and hemoglobin A1c were higher in patients treated with insulin (24.1 ± 4.2 kg/m(2), 7.1 ± 1.2%) than in patients treated with the OHA (21.2 ± 2.8 kg/m(2), 5.8 ± 0.5%; P<0.05) or diet/exercise (19.2 ± 3.6 kg/m(2), 5.3 ± 0.6%; P<0.05). The BMI and hemoglobin A1c were higher in diet/exercise compared to OHA and insulin groups.

CONCLUSION

The patients undergoing HD develop DM, especially males. The BMI and hemoglobin A1c were useful to determine whether there should be a change from insulin to OHA or to diet/exercise therapy. A dipeptidyl peptidase-IV inhibitor might be a preferable treatment for the DM patients with HD in terms of the mean and SD of PBG.

Serum albumin-adjusted glycated albumin reflects glycemic excursion in diabetic patients with severe chronic kidney disease not treated with dialysis

OBJECTIVE

Diabetic patients with severe chronic kidney disease (CKD) not treated with dialysis falsely show low levels of HbA1c and GA due to renal anemia and proteinuria, respectively. Recently, we reported that serum albumin-adjusted GA (adjGA) accurately reflects mean plasma glucose (PG) in these patients. It is considered that GA reflects not only mean PG but also glycemic excursion; therefore, in the present study we investigated whether adjGA reflects glycemic excursion in these patients.

METHODS

Thirty type 2 diabetic patients with severe CKD not treated with dialysis were enrolled in the present study. PG was monitored by seven times a day, and indicators of glycemic excursion [SD, max PG, ΔPG, M value, J index, and mean amplitude of glucose excursion (MAGE)] were calculated. The correlations between HbA1c, GA or adjGA and indicators of glycemic excursion were investigated.

RESULTS

HbA1c showed no significant correlation with indicators of glycemic excursion. GA was significantly correlated with them except for ΔPG. adjGA was significantly and strongly associated with them except for MAGE. GA, but not adjGA, showed a significant positive correlation with serum albumin.

CONCLUSION

adjGA was not influenced by serum albumin and showed a significant correlation with indicators of glycemic excursion in diabetic patients with severe CKD not treated with dialysis. These results suggest that adjGA could be useful for indicating glycemic control in diabetic patients with severe CKD not treated with dialysis.

Possible discrepancy of HbA1c values and its assessment among patients with chronic renal failure, hemodialysis and other diseases

BACKGROUND

Glycated hemoglobin (HbA1c) and glycated albumin (GA) are frequently used as glycemic control markers. However, these markers are influenced by alterations in hemoglobin and albumin metabolism. Thus, conditions such as anemia, chronic renal failure, hypersplenism, chronic liver diseases, hyperthyroidism, hypoalbuminemia, and pregnancy need to be considered when interpreting HbA1c or GA values. Using data from patients with normal albumin and hemoglobin metabolism, we previously established a linear regression equation describing the GA value versus the HbA1c value to calculate an extrapolated HbA1c (eHbA1c) value for the accurate evaluation of glycemic control. In this study, we investigated the difference between the measured HbA1c and the eHbA1c values for patients with various conditions.

METHODS

Data sets for a total of 2461 occasions were obtained from 731 patients whose HbA1c and GA values were simultaneously measured. We excluded patients with missing data or changeable HbA1c levels, and patients who had received transfusions or steroids within the previous 3 months. Finally, we included 44 patients with chronic renal failure (CRF), 10 patients who were undergoing hemodialysis (HD), 7 patients with hematological malignancies and a hemoglobin level of less than 10 g/dL (HM), and 12 patients with chronic liver diseases (CLD).

RESULTS

In all the groups, the eHbA1c values were significantly higher than the measured HbA1c values. The median difference was 0.75 % (95 % CI 0.40-1.10 %, P for the difference is <0.001) in the CRF group, 0.80 % (95 % CI 0.30-1.65 %, P for the difference is 0.041) in the HD group, 0.90 % (95 % CI 0.90-1.30 %, P for the difference is 0.028) in the HM group, and 0.85 % (95 % CI 0.40-1.50 %, P for the difference is 0.009) in the CLD group.

CONCLUSIONS

We found that the measured HbA1c values were lower than the eHbA1c values in each of the groups.

Serum albumin-adjusted glycated albumin is a better indicator of glycaemic control in diabetic patients with end-stage renal disease not on haemodialysis

Backgrounds

Diabetic patients with end-stage renal disease who are not on haemodialysis show low concentrations of HbA1c and glycated albumin due to renal anaemia and proteinuria, respectively. In the present study, we examined whether serum albumin-adjusted glycated albumin could accurately reflect glycaemic control in these patients.

Methods

To examine the correlation between glycated albumin and serum albumin (Study 1), 49 diabetic patients with end-stage renal disease not on haemodialysis were used. To evaluate the association between the glycaemic control indicators and the glycaemic control state (Study 2), 30 diabetic patients with end-stage renal disease were enrolled. The estimated HbA1c and the estimated glycated albumin concentrations were calculated based on the mean blood glucose concentrations obtained from the diurnal variation. The adjusted glycated albumin concentrations were calculated from the regression formula between the serum albumin and glycated albumin obtained from Study 1.

Results

No significant correlation was found between the measured HbA1c and estimated HbA1c concentrations. The estimated HbA1c (inversely) and measured HbA1c/estimated HbA1c ratio (positively), but not measured HbA1c, showed a significant correlation with Hb concentrations. The estimated glycated albumin was positively associated with the measured glycated albumin and adjusted glycated albumin concentrations. Although measured glycated albumin/estimated glycated albumin ratio was positively correlated with serum albumin, there was no significant association between the adjusted glycated albumin/estimated glycated albumin ratio and serum albumin, Hb and estimated glomerular filtration rate.

Conclusions

We found for the first time that the adjustment of glycated albumin by serum albumin could be useful to determine glycaemic control in diabetic patients with end-stage renal disease not on haemodialysis. These findings suggest that adjusted glycated albumin might be a better indicator of glycaemic control than measured HbA1c and measured glycated albumin in these patients.

1,5-Anhydroglucitol and glycated albumin in glycemia

The main purpose of treating diabetes is to prevent the onset and the progression of diabetic chronic complications. Since the mechanism of onset of chronic complications is still not well understood, the main strategy to achieve this purpose is to bring the plasma glucose level in diabetic patients as close as possible to that in healthy subjects and try to maintain good glycemic control over the long term. Glycated hemoglobin (HbA1c), glycated albumin (GA), fructosamine, and 1,5-anhydroglucitol (1,5 AG) are used for evaluating glycemic control. At present, HbA1c is widely used as a gold standard index for glycemic control in clinical practice. While HbA1c reflects the long-term glycemic control state (for the past 1-2 months), it does not accurately reflect glycemic control in the clinical state in which glycemic control improves or deteriorates in the short-term. It is also known that HbA1c in patients with hematological disorders such as anemia and variant hemoglobin shows an abnormal value. In addition, HbA1c mainly reflects the mean plasma glucose but does not reflect the postprandial plasma glucose. On the other hand, GA and 1,5-AG reflect intermediate- or short-term glycemic control and are not influenced by hemoglobin metabolism. While 1,5-AG is known to reflect the postprandial plasma glucose, it was shown recently that GA also reflects the postprandial plasma glucose. This chapter summarizes the measurement methods, usage methods, evidence, and problems concerning such indices for glycemic control.

Brief communication (Original). Correlation of glycated albumin with self blood glucose monitoring in diabetic patients on hemodialysis taking erythropoietin

Background: Serum glycated albumin (GA) is a marker of glycemic control in diabetic renal patients, but studies were limited by the use of few random glucose values to define glycemic control.

Objectives: To determine whether GA correlated with self blood glucose monitoring is better than HbA1c in hemodialyzed diabetic patients taking erythropoietin.

Methods: This was a cross-sectional study of diabetic patients on hemodialysis with and without erythropoietin. GA was measured by ELISA and HbA1c by ion-exchange HPLC. GA was reported as the GA/albumin ratio where albumin was measured using bromocresol green. The average capillary blood glucose level over the preceding three months (CBG) was calculated from self-reported daily prebreakfast, prelunch, and prebed glucose meter readings.

Results: Thirty-four patients were recruited; 18 were taking erythropoietin (6000 units per week) and 16 had never received erythropoietin. HbA1c correlated poorly with CBG in patients taking erythropoietin (r = -0.014, P = 0.96) compared with patients without erythropoietin (r = 0.579, P = 0.02). The correlation of GA/albumin ratio with CBG in the erythropoietin group (r = 0.612, P = 0.007) was similar to the nonerythropoietin group (r = 0.854, P < 0.001). The slope for HbA1c versus CBG was 2.8-fold greater in patients without erythropoietin compared with those taking erythropoietin. There was no significant difference in the slopes for GA/albumin ratio versus CBG between the two patient groups (P > 0.05).

Conclusion: In diabetic patients on hemodialysis and taking low doses of erythropoietin, GA/albumin is a better marker of glycemic control than HbA1c.

Defining the relationship between average glucose and HbA1c in patients with type 2 diabetes and chronic kidney disease

AIMS

To examine the relationship between average glucose (AG) and HbA1c in patients with and without chronic kidney disease (CKD) and type 2 diabetes.

MATERIALS AND METHODS

43 patients with diabetes and CKD (stages 3-5) with stable glycaemic control, and glucose-lowering and erythropoiesis stimulating agent (ESA) doses, were prospectively studied for 3 months and compared to 104 age-matched controls with diabetes, without CKD from the ADAG study. Over 3 months, AG was calculated from 7 to 8 point self-monitored blood glucose measurements (SMBG) and from continuous glucose monitoring (CGMS), and mean HbA1c was calculated from 4 measurements. AG and HbA1c relationships were determined using multivariable linear regression analyses.

RESULTS

The CKD and non-CKD groups were well matched for age and gender. Mean AG tended to be higher (p=0.08) but HbA1c levels were similar (p=0.68) in the CKD compared with non-CKD groups. A linear relationship between AG and HbA1c was observed irrespective of the presence and stage of CKD. The relationship was weaker in patients with stage 4-5 CKD (non-CKD R2=0.75, stage 3 CKD R2=0.79 and stage 4-5 CKD R2=0.34, all p<0.01). The inclusion of ESA use in the model rendered the effect of CKD stage insignificant (R2=0.67, p<0.01).

CONCLUSIONS

In patients with type 2 diabetes and CKD there is a linear relationship between HbA1c and AG that is attenuated by ESA use, suggesting that ESA results in a systematic underestimation of AG derived from HbA1c.

Evaluation of glycated albumin and microalbuminuria as early risk markers of nephropathy in type 2 diabetes mellitus

INTRODUCTION

Since Glycated Albumin (GA) reflects short term variations and glycated protein shows degrees of hyperglycaemia, the objective of this study was to find GA and microalbuminuria as a early risk markers along with the duration of Uncontrolled Diabetes Mellitus in type 2 diabetic nephropathy.

MATERIAL AND METHODS

The present cross-sectional study included randomly selected Uncontrolled Type 2DM (n = 75), controlled Type 2DM (n = 75) and healthy controls (n = 75). Their fasting venous blood samples were obtained for GA and serum creatinine, while their morning urine samples were obtained for detection of microalbuminuria. Statistical analysis was done by using SPSS, version 16.0. One-Way ANOVA was performed. All p-values which were ≤ 0.05 were considered as statistically significant.

RESULTS

The mean GA, microalbuminuria and serum creatinine were the highest in Uncontrolled DM as compared to those in Controlled DM respectively. Microalbuminuria and GA had a significant correlation with the duration of diabetes (p<0.0001).

CONCLUSION

The present study identified that the risk of microalbuminuria increased with a poor glycaemic control. A persistent increase in GA and microalbuminuria may be considered as risk markers in diabetic nephropathy. Therefore, a regular screening for microalbuminuria and estimation of GA can help in the clinical management, to prevent complications.

Serum glycated albumin is inversely influenced by fat mass and visceral adipose tissue in Chinese with normal glucose tolerance

Background

Recent studies have revealed that body mass index (BMI) inversely influenced serum glycated albumin (GA), which may cause an underestimation of GA-monitored short-term hyperglycemic control.

Objective

This study was to investigate the association between anthropometric variables (BMI and waist circumference (W)) and accurate adiposity variables (percentage of body fat (%fat), fat mass, free fat mass (FFM), subcutaneous fat area (SFA), and visceral fat area (VFA)) with serum GA.

Design

A total of 2563 subjects (1037 men, 593 premenopausal women, and 933 postmenopausal women) with normal glucose tolerance underwent bioelectrical impedance body fat content measurement and magnetic resonance imaging. Serum GA and absolute value of GA (aGA) were measured by enzymatic assay.

Results

Compared to the BMI <25.0 kg/m² group, the BMI ≥25.0 kg/m² group had significantly higher fasting plasma glucose, glycated hemoglobin A1c, and body fat parameters including W, %fat, fat mass, FFM, SFA, and VFA, but significantly lower aGA, and GA in all the three sex- and menopause-stratified groups (all P<0.05). GA decreased with the increment of fat mass for all three groups (all P for trend <0.001). In the same BMI category, men and postmenopausal women with elevated %fat (men, ≥25%; women, ≥35%) still had significantly lower GA than those with normal %fat (men, <25%; women, <35%) (all P<0.05). Multiple stepwise regression showed that %fat, fat mass, and VFA were independently associated with GA.

Conclusions

Serum GA was inversely influenced by fat mass and visceral adipose tissue in Chinese with normal glucose tolerance.

Glycated albumin, not hemoglobin A1c, predicts cardiovascular hospitalization and length of stay in diabetic patients on dialysis

BACKGROUND

The utility of glycated hemoglobin (HbA1c) and glycated albumin (GA) in diabetic dialysis patients remains unknown. GA was previously associated with all-cause hospitalization and patient survival. Relationships between GA, HbA1c, and casual plasma glucose (PG) with cause-specific cardiovascular (CV) disease, infectious disease (ID), and vascular access- (VA) related hospitalization rates and length of stay (LOS) were assessed.

METHODS

444 prevalent diabetic dialysis patients had monthly PG, quarterly GA, and all HbA1c values recorded for 2.33 years; hospitalizations within 17 and 30 days of testing were evaluated. Best-fit, time-dependent Cox models were constructed in unadjusted, case-mix-adjusted (age, sex, race, BMI, diabetes duration, dialysis vintage), and case-mix- plus lab-adjusted (hemoglobin, albumin, phosphorus) models.

RESULTS

Mean ± SD diabetes duration was 18.5 ± 10.8 years and dialysis vintage 2.9 ± 2.6 years. In fully adjusted models, CV hospitalization rates were associated with increasing GA (HR 1.32; 95% CI 1.11-1.57; p = 0.002 at 17 days; HR 1.21; p = 0.02 at 30 days) and PG (HR 1.10; 95% CI 1.02-1.17; p = 0.01 at 17 days; HR 1.07; p = 0.03 at 30 days), not HbA1c (HR 1.24; 95% CI 0.89-1.73; p = 0.21 at 17 days; HR 1.26; p = 0.10 at 30 days). LOS for CV admissions was positively associated with GA (HR 1.18; 95% CI 1.01-1.39; p = 0.03), not PG (HR 1.04; 95% CI 0.99-1.10; p = 0.15) or HbA1c (HR 1.03; 95% CI 0.92-1.15; p = 0.21). Admissions due to ID and VA complications (and LOS) did not correlate with these assays.

CONCLUSIONS

Improved glycemic control based on GA and PG predicted CV-related hospitalizations; GA also predicted CV hospitalization LOS. HbA1c did not predict cause-specific hospitalizations in dialysis populations.

Assessment of markers of glycaemic control in diabetic patients with chronic kidney disease using continuous glucose monitoring

AIM

Due to altered red blood cell survival and erythropoietin therapy glycated haemoglobin (HbA1c) may not accurately reflect long-term glycaemic control in patients with diabetes and chronic kidney disease (CKD). Glycated albumin (GA) and fructosamine are alternative markers of glycaemia. The aim of this study was to investigate the accuracy of HbA1c, GA and fructosamine as indicators of glycaemic control using continuous glucose monitoring.

METHODS

HbA1c, GA and fructosamine concentrations were measured in 25 subjects with diabetic nephropathy (CKD stages 4 and 5 (estimated glomerular filtration rate <30 mL/min per 1.73 m(2) )) matched with 25 subjects with diabetes and no evidence of nephropathy. Simultaneous real-time glucose concentrations were monitored by continuous glucose monitoring over 48 h.

RESULTS

GA correlated significantly to mean glucose concentrations in patients with and without CKD (r = 0.54 vs 0.49, P < 0.05). A similar relationship was observed with fructosamine relative to glucose. A poor correlation between HbA1c and glucose was observed with CKD (r = 0.38, P = ns) but was significant in the non-CKD group (r = 0.66, P < 0.001). The GA/HbA1c ratio was significantly higher in diabetic patients with CKD compared with controls (2.5 ± 0.4 vs 2.2 ± 0.4, P < 0.05). HbA1c values were significantly lower in CKD patients, relative to non-CKD patients at comparable mean glucose concentrations.

CONCLUSION

HbA1c significantly underestimates glycaemic control in patients with diabetes and CKD stages 4 and 5. In severe CKD, GA more accurately reflects glycaemic control compared with fructosamine and HbA1c and should be the preferred marker of glycaemic control.

Estimating average glucose levels from glycated albumin in patients with end-stage renal disease

PURPOSE

In patients with diabetic end stage renal disease (ESRD), glycated albumin (GA) reflects recent glycemic control more accurately than glycated hemoglobin (HbA1c). We evaluated the relationship between GA and average blood glucose (AG) level and developed an estimating equation for translating GA values into easier-to-understand AG levels.

MATERIALS AND METHODS

A total of 185 ESRD patients, including 154 diabetic and 31 non-diabetic participants, were enrolled (108 hemodialysis, 77 peritoneal dialysis). Patients were asked to perform four-point daily self-monitoring of capillary blood glucose (SMBG) at least three consecutive days each week for four weeks. Serum levels of GA, HbA1c and other biochemical parameters were checked at baseline, as well as at 4 and 8 weeks.

RESULTS

Approximately 74.3±7.0 SMBG readings were obtained from each participant and mean AG was 169.1±48.2 mg/dL. The correlation coefficient between serum GA and AG levels (r=0.70, p<0.001) was higher than that of HbA1c and AG (r=0.54, p<0.001). Linear regression analysis yielded the following equation: estimated AG (eAG) (mg/dL)=4.71×GA%+73.35, and with this formula, serum GA levels could be easily translated to eAG levels. Multivariate analysis revealed significant contributions of postprandial hyperglycemia (β=0.25, p=0.03) and serum albumin (β=0.17, p=0.04) in determining serum GA level, independent to other clinical parameters.

CONCLUSION

Compared to HbA1c, serum GA levels were better correlated with AG levels. Using the estimating equation, an average blood glucose level of 155-160 mg/dL could be matched to a GA value of 18-19% in patients with ESRD.

Human serum albumin: from bench to bedside

Human serum albumin (HSA), the most abundant protein in plasma, is a monomeric multi-domain macromolecule, representing the main determinant of plasma oncotic pressure and the main modulator of fluid distribution between body compartments. HSA displays an extraordinary ligand binding capacity, providing a depot and carrier for many endogenous and exogenous compounds. Indeed, HSA represents the main carrier for fatty acids, affects pharmacokinetics of many drugs, provides the metabolic modification of some ligands, renders potential toxins harmless, accounts for most of the anti-oxidant capacity of human plasma, and displays (pseudo-)enzymatic properties. HSA is a valuable biomarker of many diseases, including cancer, rheumatoid arthritis, ischemia, post-menopausal obesity, severe acute graft-versus-host disease, and diseases that need monitoring of the glycemic control. Moreover, HSA is widely used clinically to treat several diseases, including hypovolemia, shock, burns, surgical blood loss, trauma, hemorrhage, cardiopulmonary bypass, acute respiratory distress syndrome, hemodialysis, acute liver failure, chronic liver disease, nutrition support, resuscitation, and hypoalbuminemia. Recently, biotechnological applications of HSA, including implantable biomaterials, surgical adhesives and sealants, biochromatography, ligand trapping, and fusion proteins, have been reported. Here, genetic, biochemical, biomedical, and biotechnological aspects of HSA are reviewed.

Lower value of glycated haemoglobin relative to glycaemic control in diabetic patients with end-stage renal disease not on haemodialysis

BACKGROUND

Glycated haemoglobin (HbA1c) concentration is lower relative to glyacemic control in diabetic patients on haemodialysis. However, it is unknown as to whether this is also true for diabetic patients with end-stage renal disease but not on haemodialysis.

METHODS

Correlations between HbA1c or glycated albumin (GA) and estimated glomerular filtration rate (eGFR) (determined by serum creatinine concentration, sex and age) were investigated in 86 diabetic patients with renal dysfunction not on dialysis. The mean values of HbA1c and of red blood cell (RBC) lifespan were compared among four groups of patients: Group 1 (n = 30, eGFR ≥ 60 mL/min/1.73 m(2)), Group 2 (n = 30, eGFR < 60 mL/min/1.73 m(2) but ≥30 mL/min/1.73 m(2)), Group 3 (n = 13, eGFR < 30 mL/min/1.73 m(2) but ≥15 mL/min/1.73 m(2)) and Group 4 (n = 13, eGFR < 15 mL/min/1.73 m(2) without haemodialysis). RBC lifespan was determined in each subject from the difference between alveolar carbon monoxide (CO) concentration and atmospheric CO concentration.

RESULTS

HbA1c was significantly correlated with eGFR (r = 0.37, P = 0.0004), but GA was not. The HbA1c values in Group 3 (6.8 ± 0.6%) and Group 4 (6.3 ± 0.5%) were significantly lower than that in Group 1 (7.4 ± 0.8%), but there was no difference between Group 2 (7.2 ± 0.7%) and Group 1. There was a significant correlation between RBC lifespan and eGFR, and the mean RBC lifespan in Group 3 (96 ± 35 d) and Group 4 (94 ± 30 d) were significantly shorter than that in Group 1 (127 ± 30 d).

CONCLUSIONS

Diabetic patients with stage 4 or 5 chronic kidney disease not on haemodialysis had significantly lower values of HbA1c and shorter RBC lifespan compared with diabetic patients without renal dysfunction.

Glycated albumin is the preferred marker for assessing glycaemic control in advanced chronic kidney disease

Diabetic nephropathy is the most common aetiology of end-stage kidney disease (ESKD). Strict glycaemic control reduces the development and progression of diabetes-related complications, and there is evidence that improved metabolic control improves outcomes in diabetic subjects with advanced chronic kidney disease (CKD). Glycaemic control in people with kidney disease is complex. Changes in glucose and insulin homeostasis may occur as a consequence of loss of kidney function and dialysis. The reliability of measures of long-term glycaemic control is affected by CKD and the accuracy of glycated haemoglobin (HbA1c) in the setting of CKD and ESKD is questioned. Despite the altered character of diabetes in CKD, current guidelines for diabetes management are not specifically adjusted to this patient group. The validity of indicators of longer term glycaemic control has been the focus of increased recent research. This review discusses the current understanding of commonly used indicators of metabolic control (HbA1c, fructosamine, glycated albumin) in the setting of advanced CKD (Stages 4 and 5, glomerular filtration rate <30 mL/min/1.73m(2)).

Combined assessment of glycated albumin and fasting plasma glucose improves the detection of diabetes in Chinese subjects

1. The aim of the present study was to assess the validity of glycated albumin (GA) and fasting plasma glucose (FPG) as a screening tool for the early detection of diabetes in Chinese subjects. 2. A total of 1971 outpatient subjects underwent a 75 g oral glucose tolerance test (OGTT) and GA measurement. The receiver operating characteristic curve (ROC) was plotted to examine the sensitivity, specificity, and positive and negative predictive values of GA and FPG in detecting undiagnosed diabetes at the different cut-off levels. 3. The prevalence of impaired glucose regulation and diabetes was 27.40% and 38.30%. For these diabetic individuals, 4.64% had isolated fasting hyperglycemia, 50.86% had isolated postprandial hyperglycemia and 44.50% had both. Using ROC analysis, a GA of 17.1% gave an optimal sensitivity of 76.82% (95% confidence interval: 73.64-79.79%) and specificity of 76.89% (74.42-79.23%) for the diagnosis of diabetes. Likewise, a FPG of 6.1 mmol/L gave an optimal sensitivity of 80.93% (77.94-83.67%) and specificity of 85.94% (83.86-87.84%). If subjects met both criteria, they were regarded as having diabetes; the positive predictive value of the combined criteria, FPG ≥ 6.1 mmol/L and GA ≥ 17.1%, was relatively high (84.79% (81.62-87.60%)), and this would have avoided 76% of the OGTT in our survey. 4. In conclusion, a GA value of 17.1%, an optimal cut-off in Chinese subjects, identified a high proportion of potential diabetic individuals. Simultaneous measurement of FPG and GA would enhance the sensitivity of diabetes screening in our population and avoid 76% of OGTT.

Glycated albumin may be a possible alternative to hemoglobin A1c in diabetic patients with anemia

BACKGROUND

We assessed whether glycated albumin (GA) is a useful glycemic indicator in diabetic patients with anemia who did not undergo dialysis.

METHODS

Hemoglobin A(1c) (HbA(1c)) and GA were simultaneously measured in 370 diabetic subjects who had not undergone dialysis. The relationship between GA and HbA(1c) was evaluated in patients with and without anemia.

RESULTS

GA-to-HbA(1c) ratio was significantly higher (3.3±0.7 vs. 2.8±0.5, p<0.001) and the regression slope between GA and HbA(1c) was steeper in diabetic patients with than in those without anemia (6.2 vs. 4.2, p<0.001).

CONCLUSIONS

HbA(1c) was underestimated in diabetic patients with anemia than in those without anemia, with the degree of underestimation increasing as glycemic control became poorer. GA may more accurately assess glycemic control in diabetic patients with anemia than HbA(1c).

Stringent glycaemic control prolongs survival in diabetic patients with end-stage renal disease on haemodialysis

AIM

No suitable index or optimal target for diabetic control has been established for diabetic patients with end-stage renal disease (ESRD) undergoing haemodialysis. To address these issues, the single-centre observational study was conducted.

METHODS

Two hundred and forty-five diabetic ESRD patients (23.3% female; age at initiation of haemodialysis 61.7 ± 10.7 years) at start of haemodialysis between 1 January 1995 and 31 December 2004 were enrolled. Subjects were grouped according to glycaemic control level throughout the observational period as follows: mean postprandial plasma glucose (PPG) <8.9 mmol/L, 8.9 mmol/L ≤ PPG < 10.0 mmol/L, 10.0 mmol/L ≤ PPG < 11.1 mmol/L, 11.1 mmol/L ≤ PPG < 12.2 mmol/L and PPG ≥ 12.2 mmol/L; and HbA1c < 6.0%, 6.0-6.4%, 6.5-6.9% and ≥ 7.0%. Survival was then followed until 31 December 2005.

RESULTS

Cumulative survival of groups of 10.0 mmol/L ≤ PPG < 11.1 mmol/L, 11.1 ≤ PPG < 12.2 and PPG ≥ 12.2 mmol/L was significantly lower than that for PPG < 8.9 mmol/L as determined by Kaplan-Meier estimation (P = 0.016, 0.009 and 0.031, respectively; log-rank test). In both uni- and multivariate Cox proportional hazard models, mortality hazard ratios were significantly higher for PPG ≥ 10.0 mmol/L than for PPG < 8.9 mmol/L (P = 0.002-0.021). Kaplan-Meier survival curves grouped by HbA1c levels showed no correlation between HbA1c and survival during the observational period. No significant difference in mortality hazard ratios was seen for any HbA1c groups evaluated by Cox proportional hazard model.

CONCLUSION

Intensive management of diabetic control at a stringent mean on-study PPG < 10.0 mmol/L will improve the life expectancy in diabetic dialysis patients. However, no range of HbA1c values obtained in this study showed any clear difference in clinical outcomes.

Influence of proteinuria on glycated albumin values in diabetic patients with chronic kidney disease

BACKGROUND

Glycated albumin (GA), which is an alternative glycemic marker, is influenced by factors associated with albumin turnover, and it is not clear whether proteinuria influences GA values in diabetic patients with chronic kidney disease (CKD).

METHODS

We enrolled 94 diabetic patients with CKD stages 3 to 5. GA, glycated hemoglobin, and urinary protein excretion (UP) levels were consecutively obtained in each patient. The correlations between GA and UP and those between changes in GA and UP were examined.

RESULTS

There was a significant correlation between GA and UP in all cases (r=-0.46, p<0.0001), however no significant correlation was found in cases with UP of 0-3.49 g/day (r=0.01). GA values in cases with UP ≥3.5 g/day were significantly lower than those in cases with UP <3.5 g/day [UP ≥3.5 g/day and serum albumin (Alb) ≤3 g/dL; 12.0 ± 1.3%, UP ≥3.5 g/day and Alb >3 g/dL; 17.8 ± 4.3%, 0≥ UP <3.5 g/day; 21.2 ± 4.2%], while no significant difference in HbA(1c) or glucose levels was found. In cases with a minimum of UP ≥0.5 g/day, no significant correlation was found between the difference in GA and the difference in UP at the point of maximum UP and minimum UP (r=0.04).

CONCLUSION

Nephrotic-range proteinuria decreases GA values independent of the glycemic state, while non-nephrotic range proteinuria has no significant influence on GA values in diabetic CKD patients.

Glycated albumin is independently associated with estimated glomerular filtration rate in nondiabetic patients with chronic kidney disease

BACKGROUND

Glycated albumin (GA) may contribute to diabetic nephropathy, but the clinical significance of GA in patients with chronic kidney disease (CKD) is unknown.

METHODS

Patients were classified with the NKF/DOQI classification system as mild (stage I, II), moderate (stage III), or advanced CKD (stage IV). Those undergoing dialysis or with CKD stage V were excluded. GA was measured using the Lucica TM GA-L assay kit. The relationship between GA and renal dysfunction was analyzed in patients with or without diabetes.

RESULTS

A total of 187 subjects were enrolled. GA values in those with normal, mild, moderate and advanced CKD were 18.4 ± 1.4%, 18.4 ± 3.1%, 19.0 ± 3.8%, 20.4 ± 6.4%, respectively, in diabetic patients (N=67, p=0.5), and were 14.1 ± 1.9%, 14.2 ± 2.2%, 15.9 ± 1.9%, 15.0 ± 1.7%, respectively, in nondiabetic patients (N=120, p=0.004). GA value was negatively correlated to eGFR in nondiabetic patients (r=-0.35, p<0.001) but not in diabetic patients (r=-0.11, p=0.39). In the adjusted model, GA is independently correlated to eGFR only in nondiabetic subjects.

CONCLUSIONS

Increased GA concentrations are independently associated with renal dysfunction in nondiabetic patients with CKD.

[Performance characteristics of glycated albumin and its clinical usefulness in diabetic patients on hemodialysis]

BACKGROUND

The HbA1c has been considered to underestimate glucose level in diabetic patients on hemodialysis, therefore, glycated albumin (GA) was recently introduced to assess the glycemic control for those cases. We evaluated the performance of GA assay kit of Lucica GA-L (Asahi Kasei Pharma Co., Japan) and compare it with HbA1c for estimating glucose levels.

METHODS

Tests for precision, linearity and interference were performed and reference interval was determined. Thirty eight of non-hemodialysis and seventy of hemodialysis patients were recruited, whose glucose levels of three-, two- and one-month prior to this study were available for calculating weighted means of glucose (WMGs). The correlation coefficients and the slopes of regression equation between WMG and HbA1c or GA were compared between two groups. Multiple linear regression analyses were used to determine significant predictor for HbA1c and GA.

RESULTS

Total CV was 2.2% at concentration of 13.7% and 2.8% at 24.6%. The dilution curve between 15.7% and 62.1% was linear. Reference intervals were 10.0% to 16.5% for male and 11.4% to 17.6% for female. The correlation coefficients between WMG and GA were 0.682-0.713 in hemodialysis and 0.640-0.677 in non-hemodialysis. Those between WMG and HbA1c were 0.568-0.625 in hemodialysis and 0.735-0.783 in non-hemodialysis. The slopes of regression equation between GA and WMG in hemodialysis were 0.080-0.090 and 0.130-0.147 in non-hemodialysis. Those between HbA1c and WMG in hemodialysis were 0.012-0.014 and 0.029-0.032 in non-hemodialysis. GA was not influenced by hemodialysis status while HbA1c was.

CONCLUSIONS

The claimed performance characteristic of Lucica GA-L were verified. WMG were better reflected by GA rather than HbA1c in patients on hemodialysis.

Evaluation of serum biomarkers in nutritional disorders: glycated apolipoprotein B, fasting serum glucose, fructosamine, stable and labile glycated hemoglobin in diabetic and non-diabetic subjects

Glycated apolipoprotein B (ApoB-G), a non enzymatically glycated protein, has recently been associated with myocardial infarction. Our aim is to evaluate, in diabetic and non diabetic subjects, the relationship of ApoB-G with serum fasting glucose, fructosamine, stable and labile fractions of glycated hemoglobin ((S)HbA(1c), (L)HbA(1c), respectively) and insulin. The subjects were recruited from a previous study on ApoB-G and myocardial infarction: 141 of them were studied, 43 with and 98 without diabetes. ApoB-G was measured using a monoclonal antibody, and linear regression and correlation were used for statistical analysis of the data. ApoB-G was higher in diabetic than in non diabetic subjects. There was a statistically significant correlation of ApoB-G with triglycerides (r = 0.38, p = 0.01) in diabetic subjects, and with total proteins (r = 0.37, p = 0.0002), triglycerides (r = 0.34, p = 0.0007), and cholesterol (r = 0.23, p = 0.02) in non diabetic subjects. In the most parsimonious multiple linear regression model of ApoB-G on all the other serum variables, there was a statistically significant association of ApoB-G with triglycerides, in both diabetic and non diabetic subjects. The main results of this study suggest that serum ApoB-G is associated with serum triglycerides in both diabetic and non diabetic subjects.

Clinical impact of glycated albumin as another glycemic control marker

It is known that glycation among various proteins is increased in diabetic patients compared with non-diabetic subjects. Currently, among these glycated proteins, glycated hemoglobin (HbA(1C)) is used as the gold standard index of glycemic control in clinical practice for diabetes treatment. However, HbA(1C) does not accurately reflect the actual status of glycemic control in some conditions where plasma glucose changes during short term, and in patients who have diseases such as anemia and variant hemoglobin. In comparison, another index of glycemic control, glycated albumin (GA), more accurately reflects changes in plasma glucose during short term and also postprandial plasma glucose. Although GA is not influenced by disorders of hemoglobin metabolism, it is affected by disorders of albumin metabolism. This review summarizes diseases and pathological conditions where GA measurement is useful. These include the status of glycemic control changes during short term, diseases which cause postprandial hyperglycemia, iron deficiency anemia, pregnancy, chronic liver disease (liver cirrhosis), chronic renal failure (diabetic nephropathy), and variant hemoglobin.

Target for glycemic control in type 2 diabetic patients on hemodialysis: effects of anemia and erythropoietin injection on hemoglobin A(1c)

In hemodialysis (HD) patients the glycated hemoglobin (Hb(A1c)) level may underestimate glycemic control. The aim of this study is to estimate accurate glycemic control in type 2 diabetic patients on HD. Type 2 diabetes patients (N = 87) who had been receiving maintenance HD for at least one year were enrolled. Hb(A1c) and the percentage of glycated albumin relative to total the serum albumin (%GA) were measured in blood samples and the factors that affected the %GA/Hb(A1c) ratio were examined. There were significant and positive correlations between the plasma glucose and either the Hb(A1c) levels (r = 0.539, P < 0.01) or the %GA level (r = 0.520, P < 0.01). No relationship between the serum albumin levels and %GA levels was observed. A weekly dose of erythropoietin (EPO) was positively correlated with the ratio of %GA/Hb(A1c) and hematocrit (Ht) correlated negatively. There was no significant correlation between the %GA/Hb(A1c) level and the EPO dose in patients with Ht > or = 30%, although a significant correlation was found between those parameters in the Ht < 30% group. The mean of the %GA/Hb(A1c) ratios in patients with Ht > or = 30%, with Ht < 30% and treated with EPO < 100 IU/kg/week, and with Ht < 30% and treated with EPO > or = 100 IU/kg/week were 3.41, 3.56 and 4.13, respectively. In HD patients, accurate glycemic control may be estimated as: Hb(A1c) x 1.14 if Ht > or = 30%; Hb(A1c) x 1.19 if Ht < 30% and treated with low dosages of EPO; and Hb(A1c) x 1.38 if Ht < 30% and treated with high dosages of EPO.

Glycated albumin and direct low density lipoprotein cholesterol levels in type 2 diabetes mellitus

BACKGROUND

Diabetes mellitus is a major risk factor for coronary heart disease (CHD), renal failure, retinopathy, and neuropathy. Lowering glycosylated hemoglobin (HbA1c) as well as low-density lipoprotein-cholesterol (LDL-C) has been associated with a decreased risk of these complications. We evaluated the utility of glycated albumin (GA) and direct LDL-C, 2 novel assay, as compared to HbA1c and calculated LDL-C, in evaluating diabetes control and lipid in a heterogeneous population and in specific subgroups of patients with type 2 diabetes mellitus.

METHODS

We obtained fasting blood samples and measured HbA1c, GA, and direct LDL-C, as well as other parameters, in a multi-ethnic population of 616 male and female patients with type 2 diabetes and 895 non-diabetic controls.

RESULTS

HbA1c and GA levels, which measure different periods of glycemia, had a correlation of r=0.70 (p<0.001), and mean values in patients were 38.7% and 43.4% higher, respectively, than controls in men, and 41.1% and 40.1% higher, respectively, than controls, in women (both p<0.001). Calculated and direct LDL-C values correlated very highly (r=0.96, p<0.001). The correlations between HbA1c and GA, and between calculated and direct LDL-C were similar for subgroups defined by gender, race, age, and other factors.

CONCLUSIONS

Calculated LDL-C provides an accurate assessment of fasting LDL-C compared with a direct measurement in most subjects, except for those with hypertriglyceridemia, and GA correlates with HbA1c in diabetic and non-diabetic subjects and may serve as a reasonable marker of short term diabetic control.

Glycaemic control in type 2 diabetic patients on chronic haemodialysis: use of a continuous glucose monitoring system

BACKGROUND

The proportion of diabetic patients undergoing haemodialysis is rapidly increasing. Glucose control among such patients is difficult to assess. We aimed to evaluate the clinical performance of a continuous glucose monitoring system (CGMS) in type 2 diabetic patients on chronic haemodialysis.

METHODS

We used a 4-day CGMS to monitor glucose levels in 19 haemodialysed type 2 diabetic patients (HD T2) including 2 days with and 2 days without dialysis session, and 39 non-HD T2 in a double-centre study.

RESULTS

The glucose concentration according to the glucose meter and CGMS were correlated in HD T2 patients (r = 0.90, P < 0.0001) and in non-HD T2 patients (r = 0.81, P < 0.0001). The relative absolute difference (RAD) between glucose determined by a glucose meter and glucose determined by the CGMS did not differ between HD T2 and non-HD T2 patients (9.2 +/- 10.5 vs. 8.2 +/- 7.6%; P = 0.165). Glycated haemoglobin (A1c) and mean glucose concentration were strongly correlated in non-HD T2 patients (r = 0.71; P < 0.0001) but weakly correlated in HD T2 patients (r = 0.47; P = 0.042). Fructosamine was correlated with the mean glucose concentration in non-HD T2 (r = 0.67; P < 0.0001) but not in HD T2 patients (r = 0.04; P = 0.88).

CONCLUSION

CGM is a validated marker of glycaemic control in HD diabetic patients. This tool showed that A1c and fructosamine, despite being good markers of glycaemic control in non-HD diabetic patients, are of poor value in HD diabetic patients.

Influence of age and nutritional status on glycated albumin values in hemodialysis patients

OBJECTIVE

Several studies have shown glycated albumin (GA) to be a more accurate glycemic marker than HbA(1c) in diabetic patients with end-stage renal disease (ESRD). However GA values are influenced by several factors associated with albumin turnover independent of glycemia. We tried to clarify the factors other than glycemic control affecting GA values in ESRD patients.

PATIENTS AND METHODS

We examined the associations between GA values and several clinical variables related to albumin metabolism in 41 non-diabetic patients on maintenance hemodialysis.

RESULTS

Although there were no significant correlations between glucose, albumin, and GA values, there were significant correlations between age, cholinesterase (ChE) values, BMI, and GA values (r=0.515, p=0.0004, r=-0.394, p=0.010, r=-0.327, p=0.036). Stepwise multivariate regression analysis showed that age and ChE values were significant independent variables associated with GA values (beta=0.479, -0.343, R(2)=0.382).

CONCLUSION

GA values are influenced by age and nutritional status independent of glycemia in non-diabetic ESRD patients. We should be aware of factors other than glycemic control affecting GA values.

Glycated albumin levels predict long-term survival in diabetic patients undergoing haemodialysis

AIM

Glycated albumin (GA) is recognized as a reliable marker for monitoring glycemic control particularly in patients with end-stage renal disease (ESRD). Here, we investigated the impact of GA levels on long-term survival in diabetic patients with ESRD.

METHODS

We enrolled ESRD patients with diabetic nephropathy into our single-centre prospective follow-up study (n = 98, 66 men and 32 women; age 68.2 12.3 years) with a mean follow-up period of 47.7 months. All patients had started haemodialysis between December 1992 and November 2003. They were categorized into two groups according to their GA levels at the initiation of haemodialysis; GA < 29% (low-GA group; n = 54) and GA 29% (high-GA group; n = 44).

RESULTS

Between low-GA and high-GA groups, there were no significant differences in various clinical parameters except GA and HbA1c levels. The cumulative survival rate of low-GA group was significantly higher than that of high-GA group (P = 0.034, log-rank test). After adjustment for age, sex, total cholesterol, C-reactive protein and albumin, high-GA was a significant predictor of survival (hazard ratio 1.042 per 1.0% increment of GA, 95% CI 1.014-1.070, P < 0.05), but not in the case with HbA1c. Cox proportional hazard model demonstrated that high-GA group was a significant predictor for cardiovascular death (hazard ratio 2.971 (1.064-8.298), P = 0.038).

CONCLUSION

We conclude that poor glycemic control (GA 29%) before starting haemodialysis is associated with increased cardiovascular morbidity and shortened survival in diabetic patients with ESRD.