Serum glycated albumin predicts the progression of carotid arterial atherosclerosis

High glycated albumin is associated with early neurological deterioration in patients with acute ischemic stroke

BACKGROUND

Glycated albumin (GA) is an indicator of glycemic variability over the past 2-4 weeks and has suitable characteristics for predicting the prognosis of ischemic stroke during the acute phase. This study evaluated the association between early neurological deterioration (END) and GA values in patients with acute ischemic stroke (AIS).

METHODS

We assessed consecutive patients with AIS between 2022 and 2023 at two large medical centers in Korea. END was defined as an increase of ≥ 2 in the total National Institutes of Health Stroke Scale (NIHSS) score or ≥ 1 in the motor NIHSS score within the first 72 h of admission. We evaluated various glycemic parameters including fasting glucose (mg/dL), hemoglobin A1c (%), and GA (%).

RESULTS

In total, 531 patients with AIS were evaluated (median age: 69 years, male sex: 66.3%). In the multivariable logistic regression analysis, GA value was positively associated with END (adjusted odds ratio [aOR] = 3.24, 95% confidence interval [CI]: 1.10-9.50). Initial NIHSS score (aOR = 1.04, 95% CI: 1.01-1.08) and thrombolytic therapy (aOR = 2.06, 95% CI: 1.14-3.73) were also associated with END. In a comparison of the predictive power of glycemic parameters for END, GA showed a higher area under the curve value on the receiver operating characteristic curve than fasting glucose and hemoglobin A1c.

CONCLUSIONS

High GA values were associated with END in patients with AIS. Furthermore, GA was a better predictor of END than fasting glucose or hemoglobin A1c.

Association of the Ratio of Glycoalbumin to Hemoglobin A1c With Season Change and the COVID-19 Pandemic in Patients With Type 2 Diabetes Mellitus

AIM

The main purpose of the current study was to investigate the effect of season change and the influence of the COVID-19 pandemic on the ratio of glycoalbumin to hemoglobin A1c (GA/HbA1c) in patients with type 2 diabetes.

PATIENTS AND METHODS

A total of 267 patients in whom both HbA1c and GA were measured at baseline were included in this retrospective study. GA/HbA1c was investigated for three years, 2018, 2019, and 2020 (COVID-19 pandemic period).

RESULTS

The mean values for GA/HbA1c per year in 2018, 2019, and 2020 were 2.64±0.35, 2.61±0.35, 2.64±0.39, respectively. There were no significant differences in GA/HbA1c during these years. There was a tendency toward seasonal variation in GA/HbA1c (i.e., higher in summer or autumn and lower in spring or winter).

CONCLUSION

In patients with type 2 diabetes, GA/HbA1c tended to show seasonal variation, which was not influenced by the COVID-19 pandemic.

L-shaped association between the GA/HbA1c ratio and all-cause mortality in U.S. adults with NAFLD: a cross-sectional study from the NHANES 1999-2004

OBJECTIVE

It is currently unclear whether there is a relationship between the ratio of glycated albumin to hemoglobin A1c (GA/HbA1c) and mortality in individuals diagnosed with nonalcoholic fatty liver disease (NAFLD). The primary objective of the study was to investigate the relationship between the GA/HbA1c ratio and all-cause mortality in adults with NAFLD in the U.S.

METHODS

The investigation included a total of 5,295 individuals aged ≥ 18 years who were diagnosed with NAFLD, these individuals were selected from the National Health and Nutrition Examination Survey conducted between 1999 and 2004. To evaluate the outcomes of death, the researchers relied on National Death Index (NDI) records up to December 31, 2019. To better understand the nonlinear relationship between the GA/HbA1c ratio and mortality among individuals with NAFLD, this study employed both subgroup and sensitivity analyses. Furthermore, Cox proportional hazards models and two-part Cox proportional hazards model were utilized.

RESULTS

The study included a total of 5,295 adult patients with NAFLD in the U.S. During a median follow-up period of 16.9 years, there were 1,471 recorded deaths, including 419 cardiovascular deaths. After accounting for various factors, a higher GA/HbA1c ratio exhibited a positive and nonlinear association with an increased risk of all-cause mortality in patients with NAFLD. Furthermore, the study revealed an L-shaped relationship between the GA/HbA1c ratio and all-cause mortality, with the inflection point occurring at a GA/HbA1c ratio of 2.21. When the GA/HbA1c ratio exceeded 2.21, each 1-unit increase in the ratio was associated with a 33% increase in the adjusted hazard ratio (HR 1.33; 95% CI 1.14, 1.60) for all-cause mortality.

CONCLUSIONS

A nonlinear correlation between the ratio of GA to HbA1c and all-cause mortality was observed in U.S. adults with NAFLD. In addition, an elevated GA/HbA1c ratio was linked to an increased risk of all-cause mortality in these patients.

Evaluation of changes in glycemic control and diabetic complications over time and factors associated with the progression of diabetic complications in Japanese patients with juvenile-onset type 1 diabetes mellitus

BACKGROUND

This study aimed to evaluate the changes in glycemic control and diabetic complications over time in Japanese patients with juvenile-onset type 1 diabetes mellitus and to clarify the factors associated with the progression of diabetic complications.

METHODS

We tracked 129 patients with type 1 diabetes mellitus (21.8 ± 4.1 years old [mean ± SD] with a diabetes duration of 12.6 ± 5.7 years) for up to 19 years and analyzed data on glycated hemoglobin (HbA1c) and indicators related to the severity of diabetic complications (estimated glomerular filtration rate [eGFR], urinary albumin excretion rate [UAE], carotid intima-media thickness [CIMT], and brachial-ankle pulse wave velocity [baPWV]) using linear mixed model and decision tree analysis.

RESULTS

Although the HbA1c and UAE levels improved over time, the eGFR, CIMT, and baPWV worsened. Decision tree analysis showed that HbA1c and the glycoalbumin/HbA1c ratio for eGFR; HbA1c and systolic blood pressure for UAE; low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio, glycoalbumin/HbA1c ratio, and body mass index (BMI) for CIMT; and HbA1c for baPWV were associated factors.

CONCLUSIONS

In this retrospective observational study, glycemic control and albuminuria improved; however, renal function and arteriosclerosis worsened over time. HbA1c levels, glycemic excursion, and blood pressure are associated with nephropathy progression. HbA1c levels, glycemic excursion, lipid levels, and BMI are associated with the progression of atherosclerosis.

GA/HbA1c ratio is a simple and practical indicator to evaluate the risk of metabolic dysfunction-associated fatty liver disease in type 2 diabetes: an observational study

BACKGROUND

It is still debatable whether glycated albumin/glycated hemoglobin A1C (GA/HbA1C) ratio is associated with metabolic dysfunction-associated fatty liver disease (MAFLD), and few studies have been conducted in type 2 diabetes mellitus (T2DM). Therefore, we aimed to investigate the association between GA/HbA1C ratio and MAFLD and to evaluate whether GA/HbA1C ratio can be used an indicator of MAFLD in Chinese patients with T2DM.

METHODS

This cross-sectional study consisted of 7117 T2DM patients including 3296 men and 3821 women from real-world settings. Abdominal ultrasonography was performed to diagnose MAFLD. In addition to comparing the clinical characteristics among the GA/HbA1C ratio quartile groups, we also investigated the associations of GA/HbA1C ratio and quartiles with MAFLD in T2DM subjects.

RESULTS

There was a significantly decreased trend in the MAFLD prevalence across the GA/HbA1C ratio quartiles (56.3%, 47.4%, 37.8%, and 35.6% for the first, second, third, and fourth quartile, respectively, P < 0.001 for trend) after adjusting for gender, age, and diabetes duration. Fully adjusted Binary logistic regression indicated that both GA/HbA1C ratio (OR: 0.575, 95% CI: 0.471 to 0.702, P < 0.001) and quartiles (P < 0.001 for trend) were inversely associated with the presence of MAFLD among T2DM patients. Additionally, HOMA2-IR values were clearly increased in the T2DM subjects with MAFLD compared with those without MAFLD (P < 0.001), and markedly increased from the highest to the lowest GA/HbA1C ratio quartile (P < 0.001 for trend).

CONCLUSIONS

GA/HbA1C ratio is closely and negatively associated with MAFLD in T2DM subjects, which may attribute to that GA/HbA1C ratio reflects the degree of insulin resistance. GA/HbA1C ratio may act as a simple and practical indicator to evaluate the risk of MAFLD in T2DM.

Association of glycated albumin to hemoglobin A1c ratio with all-cause and cardiovascular mortality among US adults: A population-based cohort study

AIMS

To investigate the association of glycated albumin to hemoglobin A1c (GA/HbA1c) ratio, an indicator of blood glucose fluctuations, with all-cause and cardiovascular mortality among US adults.

METHODS

This cohort study used data from the National Health and Nutrition Examination Survey 1999-2004. Participants were linked to National Death Index mortality data through December 31, 2015. Cox proportional hazards model was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs), and restricted cubic spline (RCS) regression was conducted.

RESULTS

A total of 11,508 US adults (weighted mean age, 43.9 years; 5748 males [weighted, 48.9 %]) were included. During a median follow‑up of 13.6 years, 1963 total deaths occurred, including 383 cardiovascular deaths. After multivariable adjustments, a higher GA/HbA1c ratio was associated with a higher risk of all-cause (tertiles: P for trend < 0.001; continuous: HR 1.49 [95 % CI 1.32-1.69]) and cardiovascular (tertiles: P for trend = 0.048; continuous: HR 1.65 [95 % CI 1.27-2.14]) mortality. RCS revealed a linear relationship of GA/HbA1c ratio to mortality.

CONCLUSIONS

In the nationally representative cohort of US adults, GA/HbA1c ratio was significantly associated with the risk of all-cause and cardiovascular mortality. These findings suggest that GA/HbA1c ratio may serve as an effective indicator for identifying high-risk individuals.

In Vitro and In Vivo Antiglycation Effects of Connarus ruber Extract

Accumulation of advanced glycation end products (AGEs) of the Maillard reaction has been implicated in the pathogenesis of diabetes and its complications. Connarus ruber has been used as a folk remedy for several diseases, including diabetes; however, its underlying mechanism has not yet been investigated. This study investigated the effects of C. ruber extract against glycation on collagen-linked AGEs in vitro and streptozotocin-induced diabetic rats (STZ-DM rats) in vivo. The antiglycation activities of C. ruber extract and aminoguanidine (AG) were examined using a collagen glycation assay kit. Nonfluorescent AGE, N^ε-carboxymethyl lysine (CML), N^ω-carboxymethyl arginine, and N^ε-carboxyethyl lysine levels were measured via electrospray ionization-liquid chromatography-tandem mass spectrometry. The effect of the extract on the cytotoxicity of methylglyoxal (MG), a precursor of AGEs, was examined in HL60 cells. STZ-DM rats were treated with the extract for 4 wk, and the effect was assessed using biochemical markers in the serum and CML-positive cells in renal tissues. C. ruber extract dose-dependently inhibited the glycation of collagen and formation of nonfluorescent AGEs, which was comparable to AG, and it significantly attenuated MG-induced cytotoxicity in HL60 cells. Furthermore, the glycated albumin levels in STZ-DM rats decreased, the increase in serum lipid levels was reversed, and immunohistochemistry demonstrated that CML deposition in the glomerulus of STZ-DM rats significantly decreased. Although further studies are needed, C. ruber could be a potential therapeutic for preventing and progressing many pathological conditions, including diabetes.

Serum glycated albumin is associated with in-stent restenosis in patients with acute coronary syndrome after percutaneous coronary intervention with drug-eluting stents: An observational study

Background

Previous studies have confirmed the predicted value of serum glycated albumin (GA) in atherosclerotic cardiovascular disease. However, the relationship between GA and the development of in-stent restenosis (ISR) after drug-eluting stent (DES) implantation has not been verified in patients with acute coronary syndrome (ACS).

Materials and methods

In this study, 797 patients diagnosed with ACS who underwent re-coronary angiography more than 6 months after the first successful DES-based percutaneous coronary intervention (PCI) were eventually included. Patients were categorized into two groups based on the median GA levels of 14.94%. Moreover, multivariate logistic regression analysis models and the net reclassification improvement and integrated differentiation improvement risk models were constructed to assess the relationship between the GA and DES-ISR in patients with ACS.

Results

The GA was significantly associated with an increased risk of DES-ISR, upon adjusting for confounding factors (as nominal variate: OR 1.868, 95% CI 1.191-2.932, P = 0.007; as continuous variate: OR 1.109, 95% CI 1.040-1.183, P = 0.002). The addition of GA to a baseline risk model had an incremental effect on the predictive value for DES-ISR (AUC: GA vs. baseline model, 0.714 vs. 0.692, comparison P = 0.017; category-free net reclassification improvement (NRI) 0.080, P = 0.035; integrated discrimination improvement (IDI) 0.023, P < 0.001).

Conclusion

GA level was significantly associated with a high risk of DES-ISR in patients with ACS treated with PCI. Moreover, the addition of the GA to a baseline risk model has an incremental effect on the predictive potential for DES-ISR.

Glycated Albumin and Risk of Mortality in the US Adult Population

BACKGROUND

Glycated albumin is of growing interest as an alternative biomarker of glycemia. However, the association of glycated albumin with long-term outcomes in the general population is uncharacterized. We evaluated the associations of glycated albumin and hemoglobin A1c (HbA1c) with mortality in US adults.

METHODS

We conducted a prospective analysis of 12 915 participants in the National Health and Nutrition Examination Survey 1999-2004. We used Cox regression to characterize associations of glycated albumin and HbA1c with all-cause and cardiovascular mortality through 2014. We categorized glycated albumin based on percentiles corresponding to clinical cut-points for HbA1c. No diagnosed diabetes: <5.0% (<12th percentile), 5.0% to 5.6% (12th-82nd percentile, reference), 5.7% to 6.4% (83rd-97th percentile), and ≥6.5% (≥98th percentile). Diagnosed diabetes: <7.0% (<50th percentile), 7.0% to 8.9% (50th-83rd percentile), and ≥9.0% (≥84th percentile).

RESULTS

Among US adults (mean age 46 years), the prevalence of diagnosed diabetes was 6.8%. Glycated albumin and HbA1c were highly correlated (r = 0.76). Over the median 16.8 years follow-up, there were 2818 deaths (652 cardiovascular). Adults with diagnosed diabetes and glycated albumin ≥84th percentile had the highest risk for all-cause mortality [hazard ratio (HR) 3.96, 95% CI 3.06-5.13] and cardiovascular mortality (HR 6.80, 95% CI 4.20-11.03). HbA1c had associations with all-cause and cardiovascular mortality that were similar to those for glycated albumin.

CONCLUSIONS

Among US adults, increased values of glycated albumin and HbA1c were associated with all-cause and cardiovascular mortality, particularly in persons with diagnosed diabetes. Glycated albumin may be a useful alternative test of glycemia.

Glycated Albumin for Glycemic Control in T2DM Population: A Multi-Dimensional Evaluation

Purpose

To investigate the glycated albumin (GA) introduction implications, as an add-on strategy to traditional glycemic control (Hb1Ac and fasting plasma glucose – FPG) instruments, considering insulin-naïve individuals with type 2 diabetes mellitus (T2DM), treated with oral therapies.

Methods

A Health Technology Assessment was conducted in Italy, as a multi-dimensional approach useful to validate any innovative technology. The HTA dimensions, derived from the EUnetHTA Core Model, were deployed by means of literature evidence, health economics tools and qualitative questionnaires, filled-in by 15 professionals.

Results

Literature stated that the GA introduction could lead to a higher number of individuals achieving therapeutic success after 3 months of therapy (97.0% vs 71.6% without GA). From an economic point of view, considering a projection of 1,955,447 T2DM insulin-naïve individuals, potentially treated with oral therapy, GA introduction would imply fewer individuals requiring a therapy switch (−89.44%), with a 1.06% in costs reduction, on annual basis, thus being also the preferable solution from a cost-effectiveness perspective (cost-effectiveness value: 237.74 vs 325.53). According to experts opinions, lower perceptions on GA emerged with regard to equity aspects (0.13 vs 0.72, p-value>0.05), whereas it would improve both individuals (2.17 vs 1.33, p-value=0.000) and caregivers quality of life (1.50 vs 0.83, p-value=0.000). Even if in the short term, GA required additional investments in training courses (−0.80 vs 0.10, p-value = 0.036), in the long run, GA could become the preferable technology (0.30 vs 0.01, p-value=0.018) from an organisational perspective.

Conclusion

Adding GA to traditional glycaemic control instruments could improve the clinical pathway of individuals with T2DM, leading to economic and organisational advantages for both hospitals and National Healthcare Systems.

Novel molecular markers of cardiovascular disease risk in type 2 diabetes mellitus

Diabetes represents the leading risk factor for the development of cardiovascular disease (CVD). Chronic hyperglycemia and/or acute post-prandial changes in blood glucose determine an increase in reactive oxygen species (ROS), which play a fundamental role in endothelial dysfunction and in the nuclear transport of pro-atherogenic transcription factors that activate the "inflammasome". In addition, the glycemic alteration favors the formation and stabilization of atherosclerotic plaque through the mechanism of non-enzymatic glycation of different molecules, with the establishment of the so-called "advanced glycosylation end products" (AGE). Laboratory information provided by the level of biomarkers could make a quantitative and qualitative contribution to the clinical process of screening, prediction, prevention, diagnosis, prognosis and monitoring of cardiovascular (CV) risk linked to diabetes. This review describes the importance of specific biomarkers, with particular focus on novel ones, for stratifying and management of diabetes CV risk.

Oxidized Albumin as a Mediator of Kidney Disease

Renal diseases are a global health concern, and nearly 24% of kidney disease patients are overweight or obese. Particularly, increased body mass index has been correlated with oxidative stress and urinary albumin excretion in kidney disease patients, also contributing to increased cardiovascular risk. Albumin is the main plasma protein and is able to partially cross the glomerular filtration barrier, being reabsorbed mainly by the proximal tubule through different mechanisms. However, it has been demonstrated that albumin suffers different posttranslational modifications, including oxidation, which appears to be tightly linked to kidney damage progression and is increased in obese patients. Plasma-oxidized albumin levels correlate with a decrease in estimated glomerular filtration rate and an increase in blood urea nitrogen in patients with chronic kidney disease. Moreover, oxidized albumin in kidney disease patients is independently correlated with higher plasma levels of transforming growth factor beta (TGF-β1), tumor necrosis factor (TNF-α), and interleukin (IL)-1β and IL-6. In addition, oxidized albumin exerts a direct effect on neutrophils by augmenting the levels of neutrophil gelatinase-associated lipocalin, a well-accepted biomarker for renal damage in patients and in different experimental settings. Moreover, it has been suggested that albumin oxidation occurs at early stages of chronic kidney disease, accelerating the patient requirements for dialytic treatment during disease progression. In this review, we summarize the evidence supporting the role of overweight- and obesity-induced oxidative stress as a critical factor for the progression of renal disease and cardiovascular morbimortality through albumin oxidation.

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.

Traditional Risk Factors are Causally Related to Carotid Intima-Media Thickness Progression: Inferences from Observational Cohort Studies and Interventional Trials

In the present review, associations between traditional vascular risk factors (VRFs) and carotid intimamedial thickness progression (C-IMTp) as well as the effects of therapies for VRFs control on C-IMTp were appraised to infer causality between each VRF and C-IMTp. Cohort studies indicate that smoking, binge drinking, fatness, diabetes, hypertension and hypercholesterolemia are associated with accelerated C-IMTp. An exception is physical activity, with mixed data. Interventions for the control of obesity, diabetes, hypertension and hypercholesterolemia decelerate C-IMTp. Conversely, scarce information is available regarding the effect of smoking cessation, stop of excessive alcohol intake and management of the metabolic syndrome. Altogether, these data support a causative role of several traditional VRFs on C-IMTp. Shortcomings in study design and/or ultrasonographic protocols may account for most negative studies, which underlines the importance of careful consideration of methodological aspects in investigations using C-IMTp as the outcome.

Review of methods for detecting glycemic disorders

Prediabetes (intermediate hyperglycemia) consists of two abnormalities, impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) detected by a standardized 75-gram oral glucose tolerance test (OGTT). Individuals with isolated IGT or combined IFG and IGT have increased risk for developing type 2 diabetes (T2D) and cardiovascular disease (CVD). Diagnosing prediabetes early and accurately is critical in order to refer high-risk individuals for intensive lifestyle modification. However, there is currently no international consensus for diagnosing prediabetes with HbA1c or glucose measurements based upon American Diabetes Association (ADA) and the World Health Organization (WHO) criteria that identify different populations at risk for progressing to diabetes. Various caveats affecting the accuracy of interpreting the HbA1c including genetics complicate this further. This review describes established methods for detecting glucose disorders based upon glucose and HbA1c parameters as well as novel approaches including the 1-hour plasma glucose (1-h PG), glucose challenge test (GCT), shape of the glucose curve, genetics, continuous glucose monitoring (CGM), measures of insulin secretion and sensitivity, metabolomics, and ancillary tools such as fructosamine, glycated albumin (GA), 1,5- anhydroglucitol (1,5-AG). Of the approaches considered, the 1-h PG has considerable potential as a biomarker for detecting glucose disorders if confirmed by additional data including health economic analysis. Whether the 1-h OGTT is superior to genetics and omics in providing greater precision for individualized treatment requires further investigation. These methods will need to demonstrate substantially superiority to simpler tools for detecting glucose disorders to justify their cost and complexity.

Glycated Plasma Proteins as More Sensitive Markers for Glycemic Control in Type 1 Diabetes

PURPOSE

Glycated hemoglobin (HbA1c) is used clinically for diagnosis and therapeutic management of diabetes. However, HbA1c reflects average blood glucose level over a long period. The aim of this study is to look for short period, more sensitive protein markers that correlate better with glycemic level.

EXPERIMENTAL DESIGN

The glycated proteome of human plasma from type 1 diabetic individuals with good and poor (n = 20 each) glycemic control are analyzed using an online two-dimensional proteomics approach. Selected glycated peptides are further validated for their potential as candidate biomarkers using parallel reaction monitoring.

RESULTS

305 glycated peptides are quantified and 290 are significantly increased in samples with poor glycemic control. 76 of the 88 selected glycated peptides have receiver operating characteristic area under curve (AUC) values greater than 0.8. Six validated glycated peptides with high AUC show high correlation with HbA1c and have higher fold changes between poor and good glycemic control than HbA1c. The parent proteins have half-lives shorter than HbA1c.

CONCLUSIONS AND CLINICAL RELEVANCE

Using an advanced proteomics platform for protein glycation analysis, glycated peptides and proteins are identified that are promising as more sensitive, shorter term indicators of glycemic control in diabetic patients than the commonly used HbA1c.

Glycation of glucose sensitive lysine residues K36, K438 and K549 of albumin is associated with prediabetes

Prediabetes is a risk factor for the development of diabetes. Early diagnosis of prediabetes may prevent the onset and progression of diabetes and its associated complications. Therefore, this study aimed at the identification of novel markers for efficient prediction of prediabetes. In this pursuit, we have evaluated the ability of glycated peptides of albumin in predicting prediabetes. Glycated peptides of in vitro glycated albumin were characterized by data dependent acquisition and parallel reaction monitoring using LC-HRMS. Amongst 14 glycated peptides characterized in vitro, four peptides, particularly, FK(CML)DLGEENFK, K(AML)VPQVSTPTLVEVSR, K(CML)VPQVSTPTLVEVSR, and K(AML)QTALVELVK, corresponding to 3 glucose sensitive lysine residues K36, K438, and K549, respectively showed significantly higher abundance in prediabetes than control. Additionally, the abundance of three of these peptides, namely K(AML)QTALVELVK, K(CML)VPQVSTPTLVEVSR and FK(CML)DLGEENFK was >1.8-fold in prediabetes, which was significantly higher than the differences observed for FBG, PPG, and HbA1c. Further, the four glycated peptides showed a significant correlation with FBG, PPG, HbA1c, triglycerides, VLDL, and HDL. This study supports that glycated peptides of glucose sensitive lysine residues K36, K438 and K549 of albumin could be potentially useful markers for prediction of prediabetes. SIGNIFICANCE: Undiagnosed prediabetes may lead to diabetes and associated complications. This study reports targeted quantification of four glycated peptides particulary FK(CML)DLGEENFK, K(AML)VPQVSTPTLVEVSR, K(CML)VPQVSTPTLVEVSR, and K(AML)QTALVELVK, corresponding to 3 glucose sensitive lysine residues K36, K438 and K549 respectively by parallel reaction monitoring in healthy and prediabetic subjects. These peptides showed significantly higher abundance in prediabetes than healthy subjects, and showed significant correlation with various clinical parameters including FBG, PPG, HbA1c, and altered lipid profile. Therefore, together these four peptides constitute a panel of markers that can be useful for prediction of prediabetes.

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 Is a More Useful Glycation Index than HbA1c for Reflecting Renal Tubulopathy in Subjects with Early Diabetic Kidney Disease

BACKGROUND

The aim of this study was to investigate which glycemic parameters better reflect urinary N-acetyl-β-D-glucosaminidase (uNAG) abnormality, a marker for renal tubulopathy, in subjects with type 2 diabetes mellitus (T2DM) subjects with normoalbuminuria and a normal estimated glomerular filtration rate (eGFR).

METHODS

We classified 1,061 participants with T2DM into two groups according to uNAG level-normal vs. high (>5.8 U/g creatinine)-and measured their biochemical parameters.

RESULTS

Subjects with high uNAG level had significantly higher levels of fasting and stimulated glucose, glycated albumin (GA), and glycosylated hemoglobin (HbA1c) and lower levels of homeostasis model assessment of β-cell compared with subjects with normal uNAG level. Multiple linear regression analyses showed that uNAG was significantly associated with GA (standardized β coefficient [β]=0.213, P=0.016), but not with HbA1c (β=?0.137, P=0.096) or stimulated glucose (β=0.095, P=0.140) after adjusting confounding factors. In receiver operating characteristic analysis, the value of the area under the curve (AUC) for renal tubular injury of GA was significantly higher (AUC=0.634; 95% confidence interval [CI], 0.646 to 0.899) than those for HbA1c (AUC=0.598; 95% CI, 0.553 to 0.640), stimulated glucose (AUC=0.594; 95% CI, 0.552 to 0.636), or fasting glucose (AUC=0.558; 95% CI, 0.515 to 0.600). The optimal GA cutoff point for renal tubular damage was 17.55% (sensitivity 59%, specificity 62%).

CONCLUSION

GA is a more useful glycation index than HbA1c for reflecting renal tubulopathy in subjects with T2DM with normoalbuminuria and normal eGFR.

Do glycoalbumin levels preferentially reflect changes in postprandial glucose excursions?

AIMS

To evaluate whether plasma glycated albumin, which provides an integrated measure of plasma glucose levels over the preceding 2-4 weeks, better reflects changes in postprandial glucose excursions than HbA_1c .

METHODS

People with suboptimum glycaemic control on dual oral therapy were enrolled in the Treating-to-Target-in-Type 2 diabetes (4-T) trial, in which participants were randomized to the addition of once-daily basal insulin, twice-daily biphasic insulin or thrice-daily prandial insulin. Glycated albumin levels were assayed enzymatically from baseline and 1-year fasting plasma samples. We evaluated robust correlations of glycated albumin and HbA_1c both with fasting and postprandial glucose levels at these two time points, and with insulin-induced changes in the postprandial excursion.

RESULTS

Requisite data were available for 625 of the participants in the 4-T trial. Their mean (±sd) age was 62 ± 10 years and body weight was 85.8 ± 15.9 kg, and their median (interquartile range) diabetes duration was 9 (6, 13) years. Partial correlations at baseline and 1 year between postprandial glucose excursions and glycated albumin/HbA_1c , after adjusting for fasting glucose, were 0.27/0.15 and 0.22/0.18, respectively. Glycated albumin, compared with HbA_1c , explained 66% more of the variation in postprandial glucose excursions at baseline. At 1 year, postprandial glucose excursions on basal, biphasic and prandial and insulin therapy were reduced by 0.43, 0.78 and 1.88 mmol/l, respectively. These reductions were associated with changes in both glycated albumin and HbA_1c (P < 0.01), with a stronger association for glycated albumin.

CONCLUSION

Changes in glycated albumin and HbA_1c reflect changes in postprandial glucose excursions to a similar extent.

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.

Metrics Beyond Hemoglobin A1C in Diabetes Management: Time in Range, Hypoglycemia, and Other Parameters

We review clinical instances in which A1C should not be used and reflect on the use of other glucose metrics that can be used, in substitution of or in combination with A1C and SMBG, to tailor an individualized approach that will result in better outcomes and patient empowerment.

Multicenter evaluation of an enzymatic method for glycated albumin

BACKGROUND

The use of glycated albumin (GA) has been proposed as an additional glycemic control marker particularly useful in intermediate-term monitoring and in situation when HbA_1c test is not reliable.

METHODS

We have performed the first multicenter evaluation of the analytical performance of the enzymatic method quantILab Glycated Albumin assay implemented on the most widely used clinical chemistry analyzers (i.e. Abbott Architect C8000, Beckman Coulter AU 480 and 680, Roche Cobas C6000, Siemens ADVIA 2400 and 2400 XPT).

RESULTS

The repeatability of the GA measurement (expressed as CV, %) implemented in the participating centers ranged between 0.9% and 1.2%. The within-laboratory CVs ranged between 1.2% and 1.6%. A good alignment between laboratories was found, with correlation coefficients from 0.996 to 0.998. Linearity was confirmed in the range from 7.6 to 84.7%.

CONCLUSION

The new enzymatic method for glycated albumin evaluated by our investigation is suitable for clinical use.

Association of grade of non-alcoholic fatty liver disease and glycated albumin to glycated hemoglobin ratio in patients with type 2 diabetes mellitus

AIMS

The aim of this study was to investigate the association between the glycated albumin (GA) to glycated hemoglobin (HbA1c) (GA/HbA1c) ratio and grade of non-alcoholic fatty liver disease (NAFLD) on ultrasonography (US) in patients with type 2 diabetes mellitus (T2DM).

METHODS

This retrospective, cross-sectional study was performed with data obtained from 186 T2DM patients. Participants were assessed for serum GA/HbA1c ratio and fatty liver using US. NAFLD was defined as ultrasonographically detected fatty liver and was graded as normal, mild, moderate, and severe fatty liver.

RESULTS

A total of 98 subjects (53%) were diagnosed with NAFLD on US, of which 47 (48%) had moderate-to-severe grade of NAFLD. The mean GA level and GA/HbA1c ratio significantly decreased across increasing NAFLD stages (34% vs. 29% vs. 27% vs. 28%, p=0.023 for trend; 3.1vs. 2.9vs. 2.6vs. 2.7, p=0.001 for trend, respectively), whereas there was no significant difference in HbA1c level among groups (p=0.714 for trend). There was a significant decrease in prevalence of NAFLD across GA/HbA1c ratio tertiles (67% vs. 58% vs. 41%, p for trend=0.007). Multivariate logistic regression analysis showed that individuals with the lowest GA/HbA1c ratio had an odds ratio (OR) of 2.75 (95% CI=1.06-7.13) for having any grade of NAFLD and an OR of 4.48 [1.20-16.74] for moderate-to-severe grade NAFLD compared with the highest GA/HbA1c ratio even after adjustment for confounding factors (p=0.038, p=0.026, respectively).

CONCLUSION

The present study showed that GA/HbA1c ratio was significantly inversely associated with the presence and severity of NAFLD on US.

Glycated albumin and ratio of glycated albumin to glycated hemoglobin are good indicators of diabetic nephropathy in type 2 diabetes mellitus

BACKGROUND

We investigated the association between serum levels of glycated albumin (GA), glycated hemoglobin (HbA_1c ), and GA:HbA_1c ratio and the presence of diabetic nephropathy (DN) in patients with type 2 diabetes mellitus (T2DM).

METHODS

Two hundred six consecutive patients with T2DM were enrolled from the endocrinology ward at Shengjing Hospital of China Medical University and classified into 2 groups: DN group (n = 71) and non-diabetic nephropathy (non-DN) group (n = 135).

RESULTS

The DN group showed significantly higher GA and GA:HbA_1c values compared with the non-DN group. After univariate logistic regression, GA, GA:HbA_1c , HbA_1c , age, T2DM duration, systolic blood pressure, diastolic blood pressure, triglycerides, mean blood glucose (from 7 blood glucose checks), and presence of retinopathy were selected for advanced analysis. A multivariate logistic regression analysis was performed to examine the association between the presence of DN and these variables. Glycated albumin, GA:HbA_1c , duration, systolic blood pressure, mean blood glucose, and retinopathy (but not HbA_1c ) were identified as independent variables that predicted the presence of DN. We then fitted the areas under the curve of GA:HbA_1c and GA (0.811 and 0.754, respectively) separately using a receiver operating characteristic curve analysis. Both were better than HbA_1c (0.580). We defined the cutoff value of GA:HbA_1c as 2.71 (sensitivity 0.676, specificity 0.778) and that of GA as 17.5% (sensitivity 0.761, specificity 0.644) for the prediction of DN in patients with T2DM.

CONCLUSIONS

The GA:HbA_1c ratio and GA may be superior to HbA_1c associated with the presence of DN.

Glycated albumin indicates peripheral diabetic neuropathy

AIMS

We investigated associations between serum levels of glycated albumin (GA) and glycated hemoglobin (HbA1c) and the presence of diabetic peripheral neuropathy (DPN) in patients with type 1 diabetes mellitus (T1DM).

METHODS

Between September 2009 and April 2015, we evaluated 314 patients with T1DM in the Endocrinology Department of Shengjing Hospital of China Medical University. We divided the patients into the DPN group (n = 72) and the non-DPN group (n = 242), on the basis of the presence of DPN.

RESULTS

The DPN group had significantly higher GA values than the non-DPN group. After univariate logistic regression, we selected several factors for further analysis: HbA1c, GA, duration of T1DM, body mass index, smoking, hypertension, and the presence of diabetic complications, including nephropathy, retinopathy, and cardiovascular disease. We performed a multivariate logistic regression analysis to examine the association between the presence of DPN and each of these variables. We identified GA, HbA1c, hypertension, smoking, retinopathy, and cardiovascular disease as independent variables for indicating the presence of DPN. Results of a receiver operating characteristic curve analysis revealed that the area under the curve of GA (0.771) was larger than that of HbA1c (0.629). We defined the cutoff value of GA as 23.5 % (sensitivity 0.764, specificity 0.661) and the cutoff value of HbA1c as 8.45 % (sensitivity 0.667, specificity 0.595) for predicting DPN in patients with T1DM.

CONCLUSIONS

GA may be a better indicative marker of DPN in patients with T1DM than HbA1c.

Urinary N-acetyl-β-D-glucosaminidase, an early marker of diabetic kidney disease, might reflect glucose excursion in patients with type 2 diabetes

Recently, several renal tubular damage markers have gained considerable attention because of their clinical implications as sensitive and specific biomarkers for early stage diabetic kidney disease. However, little is known about the demographic and glucometabolic factors affecting levels of urinary N-acetyl-β-D-glucosaminidase (NAG), a marker of proximal tubular damage, in type 2 diabetes mellitus (T2DM).The aim of this study was to investigate the clinical relevance of urinary NAG with regard to demographic and glucometabolic parameters, as well as nephropathic parameters, by comparing the glomerulopathic marker of albuminuria.In this retrospective cross-sectional study, we enrolled a total of 592 patients with either prediabetes (N = 29) or T2DM (N = 563). Glucometabolic parameters (glucose, hemoglobin A1c, glycated albumin [GA], insulin, C-peptide, homeostasis model assessment [HOMA] of insulin resistance, HOMA-β, postprandial C-peptide-to-glucose ratio [PCGR], and urinary glucose-to-creatinine ratio) and nephropathic parameters (urinary NAG, albumin-to-creatinine ratio [ACR], and estimated glomerular filtration rate) were measured.The levels of urinary NAG showed moderate positive correlation with the levels of urinary ACR in T2DM (r = 0.46). In correlation analysis, urinary NAG was more strongly correlated with body mass index (BMI) (r = -0.22; P < 0.001 vs. r = -0.02; P = 0.74), plasma stimulated glucose (r = 0.25; P < 0.001 vs. r = 0.08; P = 0.10), GA (r = 0.20; P < 0.001 vs. r = 0.13; P = 0.01), PCGR (r = -0.17; P = 0.001 vs. r = -0.09; P = 0.11), and HOMA-β (r = -0.10; P = 0.05 vs. r = -0.02; P = 0.79) than urinary ACR. In multiple regression analysis, age, lower BMI, stimulated glucose, GA, and urinary ACR predicted increased urinary NAG.In conclusion, increase in urinary NAG may be related to glycemic parameters reflecting glucose fluctuation and decreased insulin secretory capacity in patients with T2DM. Further longitudinal, prospective studies are needed to investigate a causal relationship between glucose fluctuations, renal tubular damage, and other vascular complications of diabetes.

The association of serum glycated albumin with the prevalence of diabetic retinopathy in Korean patients with type 2 diabetes mellitus

AIMS

To determine the clinical relationship between serum glycated albumin (GA) and diabetic retinopathy in Korean patients with type 2 diabetes mellitus (T2DM).

METHODS

A cross-sectional study including 424 patients with T2DM was conducted. Patients were divided into groups based on the presence of diabetic retinopathy and tertiles of serum GA and 1,5-anhydroglucitol levels.

RESULTS

Patients in the highest tertile of GA had a higher risk of diabetic retinopathy than those in the lowest tertile. Further analysis divided the groups based on glycated hemoglobin (HbA1c) levels, either above or below 8% (64mmol/mol), and revealed that in those with a HbA1c below 8% (64mmol/mol), the higher GA subgroup had an increased presence of diabetic retinopathy.

CONCLUSIONS

An increased GA level was significantly correlated with the presence of diabetic retinopathy, and measuring GA levels in addition to HbA1c was beneficial as a marker for retinopathy, especially in patients with moderate glycemic control.

Determinants of Preclinical Atherosclerosis Are Different in Type 1 and Type 2 Diabetic Women

Diabetes mellitus type 2 ranks among the strongest predictors of cardiovascular diseases (CVD) while the association of type 1 diabetes with CVD is more complex. We studied differences between type 1 and 2 diabetic women regarding association of cardiovascular risk factors with preclinical atherosclerosis expressed as intima-media thickness of common carotid (IMT CCA) and femoral arteries (IMT CFA) measured by high resolution ultrasound. Women with type 1 (n=203) and type 2 diabetes (n=123) were examined with regard to the presence of cardiovascular risk factors. In type 1 diabetic women strong association between IMT CCA and body mass index, waist circumference, and total body fat was found in contrast to type 2 diabetic women. In type 2 diabetic women strong association between IMT CCA and fasting glucose, glycated hemoglobin, and atherogenic index of plasma (log TG/HDL cholesterol) was observed in contrast to type 1 diabetic women. In type 1 diabetic women, IMT CFA was associated with body fat in contrast to type 2 diabetic women. Preclinical atherosclerosis in type 1 diabetic women was strongly associated with factors reflecting body fat and its distribution, while in type 2 diabetic women preclinical atherosclerosis was associated with markers reflecting glucose and lipid metabolic disorders.

Glycated Albumin is Independently Associated With Arterial Stiffness in Non-Diabetic Chronic Kidney Disease Patients

Glycated albumin (GA) exhibits atherogenic effects and increased serum GA levels are associated with the development of cardiovascular complications in diabetic patients. GA production also increases with aging, oxidative stress, and renal dysfunction. We performed this study to further ascertain the association between GA and arterial stiffness in nondiabetic chronic kidney disease (CKD) patients. We enrolled 129 nondiabetic CKD patients. Arterial stiffness was measured by brachial-ankle pulse wave velocity (baPWV) using a volume plethysmographic instrument along with simultaneous measurements of GA. Insulin resistance was determined with the homeostatic model assessment. The estimated glomerular filtration rate was calculated using serum creatinine and cystatin C according to the CKD-EPI Creatinine-Cystatin C equation adjusted for age, sex, and race (eGFRcr-cys). Nondiabetic CKD patients with arterial stiffness (baPWV ≥1400 cm/s) showed higher GA levels than those without arterial stiffness (14.2 [8.7-20.2]% vs 13.0 [8.8-18.9]%, P = 0.004). In the subgroup analysis, the patients who had both a higher GA level and a lower eGFRcr-cys, showed the highest baPWV compared with patients with a higher GA or a lower GFR alone. By Spearman's correlation analysis, GA correlated significantly with baPWV (r = +0.291, P = 0.001) and fasting serum glucose level (r = +0.191, P = 0.030), whereas The homeostatic model assessment of insulin resistance did not show any significant correlation with baPWV. Systolic blood pressure (r = +0.401 P < 0.001), age (r = +0.574, P < 0.001), high-density lipoprotein (HDL)-cholesterol level (r = -0.317, P < 0.001), and eGFRcr-cys (r = -0.285, P = 0.002) had a significant correlation with baPWV. According to multivariable logistic regression analysis, higher GA and systolic blood pressure were the independent risk factors affecting arterial stiffness. Our results suggest that serum GA is a potential risk factor of arterial stiffness in nondiabetic CKD patients.

Serum Glycated Albumin to Guide the Diagnosis of Diabetes Mellitus

In the diagnosis of diabetes mellitus, hemoglobin A1c (HbA1c) is sometimes measured to determine the need of an oral glucose tolerance test (OGTT). However, HbA1c does not accurately reflect glycemic status in certain conditions. This study was performed to test the possibility that measurement of serum glycated albumin (GA) better assesses the need for OGTT. From 2006 to 2012, 1559 subjects not known to have diabetes or to use anti-diabetic medications were enrolled. Serum GA was measured, and a 75-g OGTT was then performed to diagnose diabetes. Serum GA correlated significantly to age (r = 0.27, p<0.001), serum albumin (r = -0.1179, age-adjusted p = 0.001), body mass index (r = -0.24, age-adjusted p<0.001), waist circumference (r = -0.16, age-adjusted p<0.001), and plasma GA (r = 0.999, p<0.001), but was unaffected by diet (p = 0.8). Using serum GA at 15% for diagnosis of diabetes, the sensitivity, specificity, and area under the receiver-operating characteristic curve were 74%, 85%, and 0.86, respectively. Applying a fasting plasma glucose (FPG) value of < 100 mg/dL to exclude diabetes and of ≥ 126 mg/dL to diagnose diabetes, 14.4% of the study population require an OGTT (OGTT%) with a sensitivity of 78.8% and a specificity of 100%. When serum GA value of 14% and 17% were used to exclude and diagnose diabetes, respectively, the sensitivity improved to 83.3%, with a slightly decrease in specificity (98.2%), but a significant increase in OGTT% (35%). Using combined FPG and serum GA cutoff values (FPG < 100 mg/dL plus serum GA < 15% to exclude diabetes and FPG ≥ 126 mg/dL or serum GA ≥ 17% to diagnose diabetes), the OGTT% was reduced to 22.5% and the sensitivity increased to 85.6% with no change in specificity (98.2%). In the diagnosis of diabetes, serum GA measurements can be used to determine the need of an OGTT.

Effect of improving dietary quality on carotid intima media thickness in subjects with type 1 and type 2 diabetes: a 12-mo randomized controlled trial

BACKGROUND

People with diabetes are at a heightened risk of cardiovascular disease compared with the general population. To our knowledge, randomized controlled trials investigating the effect of improving dietary quality on carotid intima media thickness, a marker of subclinical atherosclerosis and predictor of cardiovascular disease, have not been conducted in populations with diabetes.

OBJECTIVE

We aimed to determine whether increasing fruit (+1 serving; 150 g/d), vegetable (+2 servings; 150 g/d), and dairy (+1 serving; 200-250 g/d) intakes slows 12-mo common carotid artery intima media thickness (CCA IMT) progression, compared with a control group continuing to consume their usual diet, in people with type 1 and type 2 diabetes.

DESIGN

A 12-mo randomized controlled trial was conducted. The primary outcome was mean CCA IMT, measured at baseline and 12 mo, with B-mode ultrasound. Participants in the intervention group received counseling from a dietitian at baseline and 1, 3, 6, and 9 mo, and compliance was measured with a food-frequency questionnaire at baseline, 3 mo, and 12 mo. The control group continued consuming their usual diet.

RESULTS

In total, 118 participants completed the study. Vegetable (46 g/d; 95% CI: 14, 77 g/d; P < 0.001) and fruit (179 g/d; 95% CI: 119, 239 g/d; P < 0.001) intakes were increased at 3 mo in the intervention group compared with the control group. This increase was not maintained at 12 mo, but intake increased overall in the cohort (fruit, 48 g/d; vegetables, 14 g/d). An increase in dairy consumption was not achieved, but yogurt intake was higher in the intervention group at 3 mo (38 g; 95% CI: 12, 65 g; P < 0.001); this was not maintained at 12 mo. At 12 mo, CCA IMT regressed (mean ± SD: -0.01 ± 0.04 mm; P < 0.001), with a greater effect in the treatment group (mean ± SD: -0.02 ± 0.04 mm compared with -0.004 ± 0.04 mm; P = 0.009).

CONCLUSION

Improving dietary quality in people with well-controlled type 1 and type 2 diabetes may slow CCA IMT progression. This trial was registered at https://www.anzctr.org.au as ACTRN12613000251729.

Glycated Albumin Levels in Patients with Type 2 Diabetes Increase Relative to HbA1c with Time

We recently reported that glycated albumin (GA) is increased in subjects with longer duration of diabetes and with decreased insulin secretory function. Based on this, we investigated whether GA increases with time relative to glycated hemoglobin (HbA1c) and the association between GA and beta-cell function. We analyzed 340 type 2 diabetes patients whose serum GA and HbA1c levels had been repeatedly measured over 4 years. We assessed the pattern of changes with time in glycemic indices (GA, HbA1c, and GA/HbA1c ratio) and their relationship with beta-cell function. In all patients, glycemic indices decreased and maintained low levels around 15 and 27 months. However, from 39 months to 51 months, GA significantly increased but HbA1c tended to increase without statistical significance. We defined ΔGA/HbA1c as the difference between the nadir point (at 15 to 27 months) and the end point (at 39 to 51 months) and found that ΔGA/HbA1c was positively correlated with diabetes duration and negatively related to beta-cell function. In multivariable linear regression analyses, ΔGA/HbA1c was independently associated with diabetes duration. In conclusion, this study demonstrated that serum GA levels increase relative to HbA1c levels with time.

Oxidized LDL and Fructosamine Associated with Severity of Coronary Artery Atherosclerosis in Insulin Resistant Pigs Fed a High Fat/High NaCl Diet

Background

Insulin-resistant subjects develop more severe and diffuse coronary artery atherosclerosis than insulin-sensitive controls but the mechanisms that mediate this atherosclerosis phenotype are unknown.

Research Objective

To determine the metabolic parameters that associate with the severity of coronary atherosclerosis in insulin resistant pigs fed a high fat/high NaCl diet.

Key Methods

The primary endpoint was severity of coronary atherosclerosis in adult pigs (Sus scrofa, n = 37) fed a high fat diet that also contained high NaCl (56% above recommended levels) for 1 year.

Principal Findings

Twenty pigs developed severe and diffuse distal coronary artery atherosclerosis (i.e., severe = intimal area as a percent medial area > 200% in at least 2 coronary artery cross sections and diffuse distal = intimal area as a percent medial area ≥ 150% over 3 sections separated by 2 cm in the distal half of the coronary artery). The other 17 pigs had substantially less coronary artery atherosclerosis. All 37 pigs had blood pressure in a range that would be considered hypertensive in humans and developed elevations in total and LDL and HDL cholesterol, weight gain, increased backfat, and increased insulin resistance (Bergman Si) without overt diabetes. Insulin resistance was not associated with atherosclerosis severity. Five additional pigs fed regular pig chow also developed increased insulin resistance but essentially no change in the other variables and little to no detectible coronary atherosclerosis. Most importantly, the 20 high fat/high NaCl diet -fed pigs with severe and diffuse distal coronary artery atherosclerosis had substantially greater increases (p< 0.05) in oxidized LDL (oxLDL) and fructosamine consistent with increased protein glycation.

Conclusion

In pigs fed a high fat/high NaCl diet, glycated proteins are induced in the absence of overt diabetes and this degree of increase is associated with the development of severe and diffuse distal coronary artery atherosclerosis.

Association of hemoglobin A1c and glycated albumin with carotid atherosclerosis in community-dwelling Japanese subjects: the Hisayama Study

Background

It is not clear which glucose measure is more useful in the assessment of atherosclerosis. We investigated the associations of hemoglobin A_1c (HbA_1c), glycated albumin (GA), 1,5-anhydroglucitol (1,5-AG), fasting plasma glucose (FPG), and 2-hour postload glucose (PG) with carotid intima-media thickness (IMT) in community-dwelling Japanese subjects.

Methods

A total of 2702 subjects aged 40–79 years underwent a 75-g oral glucose tolerance test and measurements of HbA_1c, GA, 1,5-AG, and carotid IMT by ultrasonography in 2007–2008. Carotid wall thickening was defined as a maximum IMT of >1.0 mm. The crude and multivariable-adjusted linear and logistic regression models were used to analyze cross-sectional associations between levels of glycemic measures and carotid IMT.

Results

The crude average of the maximum IMT increased significantly with rising quartiles of HbA_1c, GA, FPG, and 2-hour PG levels in subjects with and without glucose intolerance (GI), while no clear association was observed for 1,5-AG. After adjustment for other confounding factors, positive trends for HbA_1c, GA, and FPG (all p for trend < 0.05), but not 2-hour PG (p = 0.07) remained robust in subjects with GI, but no such associations were found in those without GI. When estimating multivariable-adjusted β values for the associations of 1 SD change in glycemic measures with the maximum IMT in subjects with GI, the magnitude of the influence of HbA_1c (β = 0.021), GA (β = 0.024), and FPG (β = 0.024) was larger than that of 2-hour PG (β = 0.014) and 1,5-AG (β = 0.003). The multivariable-adjusted odds ratios for the presence of carotid wall thickening increased significantly with elevating HbA_1c, GA, and FPG levels only in subjects with GI (all p for trend < 0.001). Among subjects with GI, the area under the receiver operating characteristic curve significantly increased by adding HbA_1c (p = 0.04) or GA (p = 0.04), but not 1,5-AG, FPG, or 2-hour PG, to the model including other cardiovascular risk factors.

Conclusions

In community-dwelling Japanese subjects with GI, elevated HbA_1c, GA, and FPG levels were significantly associated with increased carotid IMT, and HbA_1c and GA provided superior discrimination for carotid wall thickening compared to 1,5-AG, FPG, and 2-hour PG, suggesting that HbA_1c and GA are useful for assessing carotid atherosclerosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-015-0247-7) contains supplementary material, which is available to authorized users.

Glycated albumin and the risk of micro- and macrovascular complications in subjects with type 1 diabetes

BACKGROUND

We investigated the relationship between the glycemic indices glycated albumin (GA) and glycated hemoglobin (HbA1c) and the progression of diabetic vascular complications [diabetic nephropathy (DN) and carotid artery atherosclerosis (CAA)] in subjects with type 1 diabetes (T1D).

METHODS

A total of 154 participants with a median follow-up of 2.8 years were enrolled in this retrospective longitudinal study. We recruited T1D subjects who had regularly measured urine albumin-creatinine ratios and estimated glomerular filtration rates, as well as tested HbA1c and GA levels consecutively every 3 or 6 months. A subgroup of 54 subjects was measured repeated carotid intima-media thickness (IMT).

RESULTS

We classified subjects into the DN progression (Group I; n = 30) with either deteriorated stages of chronic kidney disease (n = 18) or albuminuria progression (n = 17), and the non-progression (Group II; n = 124). In multiple logistic regression analyses, baseline albuminuria (odds ratio [OR] = 2.64, 95 % confidence interval [CI] = 1.03-6.74), mean GA levels (OR = 2.03, 95 % CI = 1.27-3.26) were significantly associated with progression of DN. However, there was no association with mean HbA1c (OR = 0.98, 95 % CI = 0.62-1.54). In a subgroup analysis for follow-up measurements of carotid IMT, age was independently associated with the presence of plaque and the mean IMT. However glycemic indices were not significantly associated with CAA.

CONCLUSIONS

Mean GA levels were more closely associated with DN progression than mean HbA1c in subjects with T1D. However, they were not associated with the CAA.

Glycated albumin with loss of fatty acid binding capacity contributes to enhanced arachidonate oxygenation and platelet hyperactivity: relevance in patients with type 2 diabetes

High plasma concentrations of nonesterified fatty acids (NEFAs), transported bound to serum albumin, are associated with type 2 diabetes (T2D). The effects of albumin on platelet function were investigated in vitro. Modifications of albumin, such as those due to glycoxidation, were found in patients with T2D, and the consequences of these modifications on biological mechanisms related to NEFA handling were investigated. Mass spectrometry profiles of albumin from patients with T2D differed from those from healthy control subjects. Diabetic albumin showed impaired NEFA binding capacity, and both structural and functional alterations could be reproduced in vitro by incubating native albumin with glucose and methylglyoxal. Platelets incubated with albumin isolated from patients with T2D aggregated approximately twice as much as platelets incubated with albumin isolated from healthy control subjects. Accordingly, platelets incubated with modified albumin produced significantly higher amounts of arachidonate metabolites than did platelets incubated with control albumin. We concluded that higher amounts of free arachidonate are made available for the generation of active metabolites in platelets when the NEFA binding capacity of albumin is blunted by glycoxidation. This newly described mechanism, in addition to hypoalbuminemia, may contribute to platelet hyperactivity and increased thrombosis, known to occur in patients with T2D.

Glycated albumin is more closely correlated with coronary artery disease than 1,5-anhydroglucitol and glycated hemoglobin A1c

BACKGROUND

The aim of this study was to investigate the associations of two nontraditional glycemic markers, glycated albumin (GA) and 1,5-anhydroglucitol (1,5-AG), as well as glycated hemoglobin A1c (HbA1c) with coronary artery disease (CAD).

METHODS

In total, 272 subjects (178 men and 94 postmenopausal women) were enrolled in this study. All of them underwent coronary angiography which was used to diagnose CAD. The severity of coronary artery stenosis was assessed by the coronary stenosis index (CSI). GA and 1,5-AG were assayed using the enzymatic method, and HbA1c was detected by high-pressure liquid chromatography.

RESULTS

The HbA1c and GA levels were significantly higher in CAD group than those in non-CAD group (both P < 0.01). While the 1,5-AG level was significantly lower in CAD group than that in non-CAD group (P < 0.05). After adjustment for traditional risk factors of CAD, HbA1c, 1,5-AG, and GA, multivariate logistic regression analysis showed that GA was an independent risk factor for CAD (odds ratio = 1.143, 95% confidence interval: 1.048-1.247, P = 0.002). With CSI as a dependent variable, multiple stepwise regression analysis demonstrated an independent positive correlation between GA and CSI (standardized β = 0.184, P = 0.003), beyond gender, age, and lipid-lowering therapy, after adjustment for traditional risk factors of CAD, HbA1c, 1,5-AG, and GA.

CONCLUSIONS

GA was more closely correlated with CAD than HbA1c and 1,5-AG in a Chinese population with high risk of CAD.

The glycated albumin to glycated hemoglobin ratio might not be associated with carotid atherosclerosis in patients with type 1 diabetes

BACKGROUND

The ratio of glycated albumin to glycated hemoglobin (GA/A1c) is known to be elevated in subjects with type 2 diabetes mellitus (T2DM) who had decreased insulin secretion. Additionally, the carotid intima media thickness (IMT) is greater in T2DM patients with higher GA/A1c ratios. We investigated whether increased GA/A1c ratio and IMT are also associated in type 1 diabetes mellitus (T1DM), which is characterized by lack of insulin secretory capacity.

METHODS

In this cross-sectional study, we recruited 81 T1DM patients (33 men, 48 women; mean age 44.1±13.0 years) who underwent carotid IMT, GA, and HbA1c measurements.

RESULTS

The mean GA/A1c ratio was 2.90. Based on these results, we classified the subjects into two groups: group I (GA/A1c ratio <2.90, n=36) and group II (GA/A1c ratio ≥2.90, n=45). Compared with group I, the body mass indexes (BMIs), waist circumferences, and IMTs were lower in group II. GA/A1c ratio was negatively correlated with BMI, urine albumin to creatinine ratio (P<0.001 for both), and both the mean and maximal IMT (P=0.001, both). However, after adjusting the confounding factors, we observed that IMT was no longer associated with GA/A1c ratio.

CONCLUSION

In contrast to T2DM, IMT was not significantly related to GA/A1c ratio in the subjects with T1DM. This suggests that the correlations between GA/A1c ratio and the parameters known to be associated with atherosclerosis in T2DM could be manifested differently in T1DM. Further studies are needed to investigate these relationships in T1DM.

Serum glycated albumin predicts the progression of diabetic retinopathy--a five year retrospective longitudinal study

AIMS

To assess the predictive value of glycated albumin (GA) and other risk factors on a progression of diabetic retinopathy (DR).

METHODS

In this retrospective longitudinal study, we enrolled the subjects with type 2 diabetes who had undergone fundus photography twice with a 5-years gap between January 2006 and December 2012, and had been measured consecutively for hemoglobin A1c (HbA1c) and GA levels every 3 or 6 months. The subjects were divided into two groups with or without a progression of DR. The mean HbA1c and mean GA were calculated separately by the sum of all measured values divided by the numbers of values throughout the study period.

RESULTS

Of the 359 subjects, progression group showed significantly higher diabetes duration (8.41±5.72 vs. 6.46±5.77, P<0.01), baseline HbA1c (9.13±2.71 vs. 8.41±2.32, P<0.05), fasting plasma glucose (8.71±2.78 vs. 7.94±2.63, P<0.05), 2h-postprandial glucose (15.12±11.20 vs.13.14±4.72, P<0.05), eGFR (114.81±39.15 vs. 103.23±32.18, P<0.01), mean HbA1c (8.32±1.69 vs. 7.39±1.35, P<0.01) and mean GA (22.66±5.92 vs. 19.83±5.18, P<0.01) than non-progression group. The frequencies of subjects with DR progression increased obviously with the increment of baseline HbA1c, mean HbA1c and mean GA according to quartile stratification of the above three glucose parameters. Multivariable binary logistic regression analysis investigated that the factors affected the DR progression were the presence of DR at baseline (OR=0.391, P=0.005), mean HbA1c (OR=1.389, P=0.021), mean GA (OR=1.087, P=0.039) and eGFR (OR=1.008, P=0.045). The optimal cut-off values of mean HbA1c and GA to predict DR progression were 7.27% and 21.85%, respectively.

CONCLUSIONS

The presence of DR at baseline, poor glycemic control, glycated albumin, and impaired renal function predicted DR progression in patients with type 2 diabetes.

Glycemic variability and oxidative stress: a link between diabetes and cardiovascular disease?

Diabetes is associated with a two to three-fold increase in risk of cardiovascular disease. However, intensive glucose-lowering therapy aiming at reducing HbA1c to a near-normal level failed to suppress cardiovascular events in recent randomized controlled trials. HbA1c reflects average glucose level rather than glycemic variability. In in vivo and in vitro studies, glycemic variability has been shown to be associated with greater reactive oxygen species production and vascular damage, compared to chronic hyperglycemia. These findings suggest that management of glycemic variability may reduce cardiovascular disease in patients with diabetes; however, clinical studies have shown conflicting results. This review summarizes the current knowledge on glycemic variability and oxidative stress, and discusses the clinical implications.

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.

Optimal glycated albumin cutoff value to diagnose diabetes in Korean adults: a retrospective study based on the oral glucose tolerance test

INTRODUCTION

Glycated albumin (GA) reflects short-term status of glycemic control. We suggest a GA cut-off value to diagnose pre-diabetes and diabetes in Korean adults. In addition, we compared the performance of GA for the diagnosis of diabetes with that of glycated hemoglobin (A1c).

MATERIALS AND METHODS

A total of 852 subjects (498 males, 354 females) aged 20 to 83years (mean: 52.5years) were enrolled. A 75-g oral glucose tolerance test (OGTT) was performed and A1c and GA were measured.

RESULTS

In these enrolled subjects, 88% have glucose intolerance status (pre-diabetes or diabetes). The GA concentrations corresponding to fasting plasma glucose (FPG) of 7.0mmol/l, 2-h plasma glucose during OGTT (PPG2)≥11.1mmol/l, and A1c≥6.5% were 14.6%, 13.7%, and 14.7%, respectively. A meta-analysis of three GA cutoffs revealed a GA cutoff for diabetes of 14.3%. When A1c is used in combination with FPG, the sensitivity and specificity for the diagnosis of OGTT-based diabetes were 72.16% (95% CI: 66.6-72.2) and 96.4% (95% CI: 94.4-97.7), respectively. With the newly developed GA cutoff of 14.3%, GA combined with FPG resulted in a sensitivity and specificity of 77.5% (95% CI: 72.17-82.0) and 89.9% (95% CI: 87.1-92.2), respectively.

CONCLUSIONS

A GA cutoff of >14.3% is optimal for the diagnosis of diabetes in Korean adults. The measurement of FPG and GA may detect diabetes earlier than the measurement of FPG and A1c.

Development of an HbA1c-based conversion equation for estimating glycated albumin in a Korean population with a wide range of glucose intolerance

Background

Compared to the golden standard glycation index of HbA1c, glycated albumin (GA) has potentials for assessing insulin secretory dysfunction and glycemic fluctuation as well as predicting diabetic vascular complications. However, the reference ranges of GA and a conversion equation need to be clearly defined. We designed this study to determine the reference ranges in patients with normal glucose tolerance (NGT) based on conventional measures of glycemic status and to devise a conversion equation for calculating HbA1c and GA in a Korean population.

Methodology/Principal Findings

In this multicenter, retrospective, cross-sectional study, we recruited antidiabetic drug-naïve patients with available glycemic variables including HbA1c, GA, and fasting plasma glucose regardless of glucose status. For the reference interval of serum GA, 5^th to 95^th percentile value of GA in subjects with NGT was adopted. The conversion equation between HbA1c and GA was devised using an estimating regression model with unknown break-points method. The reference range for GA was 9.0–14.0% in 2043 subjects. The 95^th percentile responding values for FPG, and HbA1c were approximately 5.49 mmol/l, and 5.6%, respectively. The significant glycemic turning points were 5.868% HbA1c and 12.2% GA. The proposed conversion equation for below and above the turning point were GA (%) = 6.960+0.8963 × HbA1c (%) and GA (%) = −9.609+3.720 × HbA1c (%), respectively.

Conclusions/Significance

These results should be helpful in future studies on the clinical implications of high GA relative to HbA1c and the clinical implementation of diabetes management.

Glycated albumin; clinical usefulness

The main purpose of treating diabetes is to prevent the onset and 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 plasma glucose levels as close as possible to those in healthy subjects and maintain good glycemic control over the long term. Since glycation among various proteins is increased in diabetic patients compared with non-diabetic subjects, glycated protein can be used as a glycemic control indicator. Currently, among these glycated proteins, HbA1c is used as the gold standard of glycemic control indicators. However, HbA1c does not accurately reflect the actual status of glycemic control in some conditions with rapid changes in glycemic control and in patients with anemia (hemolytic anemia, iron deficiency anemia, etc.) and variant hemoglobin. In comparison, glycated albumin (GA) more accurately reflects changes in plasma glucose during the short term and postprandial plasma glucose. GA also reflects glycemic control in patients with hematologic disorders whereas GA does not reflect glycemic control in patients with disorder of albumin metabolism. GA is a glycemic control indicator which overcomes most of the disadvantages of HbA1c, and could be therefore expected to replace HbA1c as the standard glycemic control indicator in the near future. However, it is necessary to accumulate more evidences from large research studies on the effective directions for measuring GA.

Beyond HbA1c and glucose: the role of nontraditional glycemic markers in diabetes diagnosis, prognosis, and management

Fasting glucose and hemoglobin A1c (HbA1c) are the standard measures for diagnosis and monitoring of diabetes. There has been recent interest in nontraditional markers of hyperglycemia, including fructosamine, glycated albumin, and 1,5-anhydroglucitol (1,5-AG), as alternatives or adjuncts to standard measures. There is a growing literature linking these nontraditional markers with microvascular and macrovascular complications. Fructosamine and glycated albumin have also been shown to improve identification of persons with diabetes. However, long-term prospective studies with clinical outcomes are lacking. Some modern laboratory assays for fructosamine, glycated albumin, and 1,5-AG have excellent performance. Expanded use of these tests has the potential to improve diabetes care as these measures may overcome limitations of HbA1c in certain patients, complement traditional measures by providing additional information on shorter-term glycemic control, and improve risk stratification for diabetes and its complications. Nonetheless, studies are needed to demonstrate if their routine use will benefit patients and improve outcomes.

Lower beta cell function relates to sustained higher glycated albumin to glycated hemoglobin ratio in Japanese patients with type 2 diabetes

The aim of this study was to clarify the relationship between baseline beta cell function and future glycated albumin (GA) to glycated hemoglobin ratio (GA/HbA1c) in patients with type 2 diabetes. In our retrospective cohort, 210 type 2 diabetic patients who had been admitted to our hospital and in whom HbA1c and GA had been measured at baseline and 2 years after admission were included in this study. Baseline beta cell function was assessed by postprandial C-peptide immunoreactivity index (PCPRI) during admission. With intensification of treatment during admission, HbA1c and GA were significantly decreased 1 year and 2 years after admission. While baseline HbA1c was not significantly correlated with HbA1c after 2 years, baseline GA/HbA1c was strongly correlated with GA/HbA1c after 2 years (r = 0.575, P <0.001). When the patients were divided into two groups according to median PCPRI, patients with low PCPRI showed higher GA/HbA1c both at baseline and after 2 years compared to those with high PCPRI. There was a significant negative correlation between PCPRI and GA/HbA1c after 2 years (r = -0.379, P <0.001). Multiple regression analysis revealed that PCPRI was an independent predictor of GA/HbA1c after 2 years. In conclusion, our findings suggest that lower beta cell function is associated with sustained higher GA/HbA1c ratio in patients with type 2 diabetes.