Serum glycated albumin levels are influenced by smoking status, independent of plasma glucose levels

U-shaped associations between glycated albumin and obesity and role of IL-10 in hyperacute ischemic stroke

OBJECTIVE

There is growing interest in the use of new biomarkers such as glycated albumin (GA). In contrast to glycated hemoglobin (HbA1c), GA showed an inverse correlation with prestroke obesity status, but data are limited for ischemic stroke (IS).

MATERIALS AND METHODS

We explored the association between GA and body mass index (BMI) and investigated inflammatory cytokines to support the academic background. In total, 155 patients with hyperacute IS (HIS) between 2011 and 2019 were included. To identify the association between GA and BMI, patients were divided into four groups according to BMI quartiles. Levels of inflammatory cytokines, including IL-1β, IL-10, IL-6, TNF-α, and TNF-R1, were determined by ELISA using a ProcartaPlex multiplex immunoassay.

RESULTS

The mean age of the 155 patients was 68 ± 12 years, and 67.1% were men. The lowest BMI group had higher GA levels (GA 2 T and 3 T = 80%) (p-value=0.017), and these U-shaped associations were maintained only for small vessel occlusion etiology (p-value= 0.004). Plasma IL-10 levels were positively correlated with BMI and showed a U-shaped pattern (p-value= 0.001).

CONCLUSION

GA levels and BMI had U-shaped associations with HIS. IL-10, which acts as a protective cytokine for cardiovascular disease, may play a novel role in this association. Although GA is an emerging favorable clinical marker of cardiovascular outcomes, obesity status should be considered when interpreting these associations.

Smokers with Elevated Glycated Albumin Could Not Benefit from Dual Antiplatelet Therapy after Minor Stroke or Transient Ischemic Attack

INTRODUCTION

The aim of this study was to investigate the impact of smoking on dual antiplatelet therapy in patients with minor stroke or transient ischemic attack (TIA) under different glycated albumin (GA) levels.

METHODS

We analyzed data from the Clopidogrel in High-Risk Patients with Acute Nondisabling Cerebrovascular Events (CHANCE) trial. A subgroup of 3,044 patients with baseline GA levels was included and categorized by smoking status and GA levels. The primary efficacy outcome was a new stroke within 90 days. The safety outcome was any bleeding event at 90 days. The interaction of smoking status with antiplatelet therapy was calculated by Cox proportional hazards regression model.

RESULTS

In patients with GA levels ≤15.5%, the proportion of smokers was 37.7% (719/1,908), while in patients with GA levels >15.5%, it was 51.6% (586/1,136). During the 3-month follow-up period, 299 (9.9%) patients had a new stroke occurrence. In patients with elevated GA levels, both smokers and nonsmokers could not benefit from dual antiplatelet therapy (smokers, adjusted hazard ratio [HR] 0.70, 95% confidence interval [CI]: 0.42-1.17; nonsmokers, adjusted HR 0.82, 95% CI: 0.57-1.18). In patients with normal GA levels, dual antiplatelet therapy reduced the risk of stroke recurrence in smokers by 72% (adjusted HR 0.28, 95% CI: 0.14-0.56) and in nonsmokers by 53% (adjusted HR 0.47, 95% CI: 0.26-0.86). However, whether the GA level was elevated or normal, there was no significant interaction between smoking status and antiplatelet therapy.

CONCLUSIONS

Smokers with elevated GA levels could not benefit from dual antiplatelet therapy after minor stroke or TIA.

Serum Glycated Albumin Levels Are Affected by Alcohol in Men of the Jinuo Ethnic Group in China

AIM

To investigate the effects of alcohol on serum glycated albumin (GA) levels in Chinese men.

METHODS

A total of 2314 male subjects from the Jinuo ethnic group in China were enrolled. Of these, 986 subjects drank alcohol frequently and 404 subjects did not. Lifestyle information was gathered by using a questionnaire, and measurements of blood pressure, body mass index, blood glucose level, liver function, and kidney function were collected. GA was measured by using an enzymatic method. Frequent drinking was defined as a history of drinking ethanol > 80 g/d within the past two weeks. Nondrinking was defined as no alcohol consumption in the past three months. Subjects with an alcohol intake between 0 and 80 g/d in the past two weeks were included in the drinking-occasionally group. Analysis of variance (ANOVA), correlation analysis, and linear regression were used to evaluate the effects of drinking on serum GA levels. Decision tree regression (DTR) algorithm was used to evaluate the effect of features (variables) on GA levels.

RESULTS

We found that male subjects who drank frequently had significantly lower serum GA levels than subjects who did not drink (13.0 ± 1.7 vs. 14.1 ± 3.7, p < 0.05). Spearman's correlation analysis calculated a coefficient of -0.152 between drinking and GA (p < 0.005). Linear regression established that drinking was an independent predictor for GA levels with a standardized regression coefficient of -0.144 (p < 0.05). Decision tree regression showed that the effect of drinking on GA levels (0.0283) is five times higher than that of smoking (0.0057).

CONCLUSIONS

Frequent alcohol consumption could result in decreased GA levels in men of the Jinuo ethnic group in China.

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.

Results of a Study Comparing Glycated Albumin to Other Glycemic Indices

CONTEXT

Intermediate-term glycemic control metrics fulfill a need for measures beyond hemoglobin A1C.

OBJECTIVE

Compare glycated albumin (GA), a 14-day blood glucose measure, with other glycemic indices.

DESIGN

24-week prospective study of assay performance.

SETTING

8 US clinics.

PARTICIPANTS

Subjects with type 1 (n = 73) and type 2 diabetes (n = 77) undergoing changes to improve glycemic control (n = 98) or with stable diabetes therapy (n = 52).

INTERVENTIONS

GA, fructosamine, and A1C measured at prespecified intervals. Mean blood glucose (MBG) calculated using weekly self-monitored blood glucose profiles.

MAIN OUTCOME MEASURES

Primary: Pearson correlation between GA and fructosamine. Secondary: magnitude (Spearman correlation) and direction (Kendall correlation) of change of glycemic indices in the first 3 months after a change in diabetes management.

RESULTS

GA was more concordant (60.8%) with changes in MBG than fructosamine (55.5%) or A1C (45.5%). Across all subjects and visits, the GA Pearson correlation with fructosamine was 0.920. Pearson correlations with A1C were 0.655 for GA and 0.515 for fructosamine (P < .001) and with MBG were 0.590 and 0.454, respectively (P < .001). At the individual subject level, Pearson correlations with both A1C and MBG were higher for GA than for fructosamine in 56% of subjects; only 4% of subjects had higher fructosamine correlations with A1C and MBG. GA had a higher Pearson correlation with A1C and MBG in 82% and 70% of subjects, respectively.

CONCLUSIONS

Compared with fructosamine, GA correlates significantly better with both short-term MBG and long-term A1C and may be more useful than fructosamine in clinical situations requiring monitoring of intermediate-term glycemic control (NCT02489773).

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.

Glycated albumin is stable in plasma when exposed to common laboratory conditions and comparable when drawn from venous or capillary sites

BACKGROUND

Circulating glycated albumin is a marker of blood glucose reflecting the previous 2 weeks. However, the effects of storage conditions and draw site on glycated albumin values are not fully understood.

METHODS

Fifteen plasma samples from people with type 2 diabetes were assessed during repeated freeze-thaw rounds for 10 cycles. A further 15 samples were stored at 4°C and assessed over 3 days. Another 40 samples drawn concurrently from capillary and venous sites had their glycated albumin content compared.

RESULTS

Glycated albumin concentration did not alter over 10 freeze-thaw cycles (P=.856), or after 72 hours at 4°C (P=.962). Capillary and venous samples did not differ in their percentage of glycated albumin (P=.379), although lower concentrations of albumin and glycated albumin (g/dL) were observed in the capillary sample (P<.001).

CONCLUSION

Glycated albumin in plasma appears relatively stable when exposed to common laboratory conditions, reducing a potential confounder to its use as a marker of blood glucose control. The glycated albumin (%) in samples from capillary and venous sites was comparable, suggesting the potential of rapid or portable assessment devices that require a finger prick.

Evaluation of glycated albumin (GA) and GA/HbA1c ratio for diagnosis of diabetes and glycemic control: A comprehensive review

Diabetes Mellitus (DM) is a group of metabolic diseases characterized by chronic high blood glucose concentrations (hyperglycemia). When it is left untreated or improperly managed, it can lead to acute complications including diabetic ketoacidosis and non-ketotic hyperosmolar coma. In addition, possible long-term complications include impotence, nerve damage, stroke, chronic kidney failure, cardiovascular disease, foot ulcers, and retinopathy. Historically, universal methods to measure glycemic control for the diagnosis of diabetes included fasting plasma glucose level (FPG), 2-h plasma glucose (2HP), and random plasma glucose. However, these measurements did not provide information about glycemic control over a long period of time. To address this problem, there has been a switch in the past decade to diagnosing diabetes and its severity through measurement of blood glycated proteins such as Hemoglobin A1c (HbA1c) and glycated albumin (GA). Diagnosis and evaluation of diabetes using glycated proteins has many advantages including high accuracy of glycemic control over a period of time. Currently, common laboratory methods used to measure glycated proteins are high-performance liquid chromatography (HPLC), immunoassay, and electrophoresis. HbA1c is one of the most important diagnostic factors for diabetes. However, some reports indicate that HbA1c is not a suitable marker to determine glycemic control in all diabetic patients. GA, which is not influenced by changes in the lifespan of erythrocytes, is thought to be a good alternative indicator of glycemic control in diabetic patients. Here, we review the literature that has investigated the suitability of HbA1c, GA and GA:HbA1c as indicators of long-term glycemic control and demonstrate the importance of selecting the appropriate glycated protein based on the patient's health status in order to provide useful and modern point-of-care monitoring and treatment.

Low fructosamine and mortality - A long term follow-up of 215,011 non-diabetic subjects in the Swedish AMORIS study

BACKGROUND AND AIMS

Both high and low fasting glucose has been associated with an increased mortality among individuals without diabetes. This J-shaped association has also been shown for HbA1c in relation to all-cause mortality. High fructosamine is associated with increased mortality. In this study we aim to evaluate if low fructosamine is also associated with increased mortality in non-diabetic subjects.

METHODS AND RESULTS

We included 215,011 subjects from the AMORIS cohort undergoing occupational health screening or primary care in Stockholm, Sweden. Cause specific mortality was obtained from the Swedish Cause-of-Death Register by record linkage. Hazard ratios for the lowest decile of fructosamine were estimated by Cox regression for all-cause (n = 41,388 deaths) and cause-specific mortality during 25 years of follow-up. We observed gradually increased mortality with lower fructosamine in a large segment of the population. In the lowest decile of fructosamine the sex, age, social class and calendar adjusted hazard ratio was 1.20 (95% CI; 1.18-1.27) compared to deciles 2-9. This increased mortality was attenuated after adjustment for six other biomarkers (HR = 1.11 (95% CI; 1.07-1.15)). Haptoglobin, an indicator of chronic inflammation, made the greatest difference in the point estimate. In sensitivity analyses we found an association between low fructosamine and smoking and adjustment for smoking further attenuated the association between low fructosamine and mortality.

CONCLUSION

Low levels of fructosamine in individuals without diabetes were found to be associated with increased mortality. Smoking and chronic inflammation seem to at least partially explain this association but an independent contribution by low fructosamine cannot be excluded.

Fructosamine and Glycated Albumin and the Risk of Cardiovascular Outcomes and Death

BACKGROUND

Hemoglobin A1c (HbA1c) is the standard measure to monitor glucose control in diabetes mellitus and is a marker of future cardiovascular risk. Fructosamine and glycated albumin are markers of short-term glycemic control, but their associations with cardiovascular outcomes are uncharacterized.

METHODS AND RESULTS

We measured glycated albumin and fructosamine in 11 104 participants with and without diabetes in the community-based Atherosclerosis Risk in Communities (ARIC) Study in 1990 to 1992 (baseline). We evaluated associations of fructosamine and glycated albumin with risk of coronary heart disease, ischemic stroke, heart failure, and mortality. We compared associations with those observed for HbA1c. During two decades of follow-up there were 1096 new cases of coronary heart disease, 605 of ischemic stroke, 1432 of heart failure, and 2860 deaths. Elevated baseline concentrations of fructosamine and glycated albumin were significantly associated with each of the outcomes even after adjustment for traditional cardiovascular risk factors, with especially strong associations in persons with diabetes mellitus. Associations were of similar magnitude to those observed for HbA1c and-as has been previously observed for HbA1c-the associations tended to be J-shaped, with an elevation of risk at the lowest levels of each biomarker.

CONCLUSIONS

The acceptance of new measures of hyperglycemia is partly dependent on establishing their association with long-term outcomes. We found that fructosamine and glycated albumin were associated with vascular outcomes and mortality and that these associations were similar to those observed for HbA1c.

Glycated Serum Albumin and AGE Receptors

In vivo modification of proteins by molecules with reactive carbonyl groups leads to intermediate and advanced glycation end products (AGE). Glucose is a significant glycation reagent due to its high physiological concentration and poorly controlled diabetics show increased albumin glycation. Increased levels of glycated and AGE-modified albumin have been linked to diabetic complications, neurodegeneration, and vascular disease. This review discusses glycated albumin formation, structural consequences of albumin glycation on drug binding, removal of circulating AGE by several scavenger receptors, as well as AGE-induced proinflammatory signaling through activation of the receptor for AGE. Analytical methods for quantitative detection of protein glycation and AGE formation are compared. Finally, the use of glycated albumin as a novel clinical marker to monitor glycemic control is discussed and compared to glycated hemoglobin (HbA1c) as long-term indicator of glycemic status.

Uric acid is associated with metabolic syndrome in children and adults in a community: the Bogalusa Heart Study

BACKGROUND

Elevated serum uric acid (UA) is commonly found in subjects with metabolic syndrome (MetS). This study examined the association of UA with levels of individual MetS components and the degree of their clustering patterns in both children and adults.

METHODS

The study sample consisted of 2614 children aged 4-18 years and 2447 adults aged 19-54 years. MetS components included body mass index (BMI), mean arterial pressure (MAP), triglycerides to high-density lipoprotein cholesterol ratio (TG/HDLC), and homeostasis model assessment of insulin resistance (HOMA). Observed/expected (O/E) ratio and intra-class correlation coefficient (ICC) were used as a measure of the degree of clustering of categorical and continuous MetS variables, respectively.

RESULTS

UA was positively and significantly associated only with BMI in children but with all four components in adults. The odds ratio for MetS associated with 1 mg/dL increase of UA was 1.74 (p<0.001) in children and 1.92 (p<0.001) in adults. O/E ratios showed a significant, increasing trend with increasing UA quartiles in both children and adults for 3- and 4-variable clusters with p-values for trend <0.001, except for BMI-MAP-TG/HDLC and MAP-TG/HDLC-HOMA clusters in children and MAP-TG/HDLC-HOMA cluster in adults. ICCs of 3 and 4 components increased with increasing UA quartiles in children and adults.

CONCLUSIONS

These results indicate that UA may play a role in the development of MetS in both pediatric and adult populations alike, which may aid in the identification and treatment of high risk individuals for MetS and related clinical disorders in early life.

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.

Serum glycated albumin, but not glycated hemoglobin, is low in relation to glycemia in men with hypertriglyceridemia

Aims/Introduction:  Serum glycated albumin (GA) and glycated hemoglobin (HbA1c) are influenced by plasma glucose levels, and are used for monitoring chronic glycemic control in diabetic patients. Both glycated proteins are known to be influenced by various factors other than plasma glucose levels. In the present study, we examined the effects of hypertriglyceridemia on them.

MATERIALS AND METHODS

  The present study comprised 273 non-diabetic men. They were grouped into men with normotriglyceridemia (serum triglyceride [TG] <150 mg/dL) and those with hypertriglyceridemia (serum TG ≥150 mg/dL).

RESULTS

  Body mass index (BMI) and high sensitivity C-reactive protein (hs-CRP) were significantly higher in the 160 men with hypertriglyceridemia than the 113 men with normotriglyceridemia. In men with hypertriglyceridemia, as compared with those with normotriglyceridemia, fasting plasma glucose, 2-h plasma glucose after 75 g oral glucose tolerance test, and HbA1c were significantly higher. By contrast, serum GA was significantly lower in men with hypertriglyceridemia. BMI-adjusted serum GA was also significantly lower in these men. In a multivariate analysis, serum TG was an inverse explanatory variable for serum GA.

CONCLUSIONS

  Serum GA is low in relation to plasma glucose levels in men with hypertriglyceridemia. This might be caused by increased albumin metabolism associated with hypertriglyceridemic state. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2010.00049.x, 2010).

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.

Effect of smoking status on healthcare costs and resource utilization in patients with type 2 diabetes in routine clinical practice: a retrospective nested case-control economic study

AIM

To compare healthcare resource utilization and costs according to smoking status in patients with type 2 diabetes in clinical practice.

METHODS

A retrospective cohort nested case-control study was designed. Cases were current smokers, while 2 types of controls (former smokers and never smokers) were matched (2 controls per case) for age, sex, duration of diabetes and burden of comorbidity using data from medical records. Noninstitutionalized diabetics of both genders, aged>18 years and seen consecutively over a 5-year period before the index date, were enrolled. Analysis compared healthcare resource utilization, loss of productivity due to sick leave and corresponding costs.

RESULTS

In total, 2,490 medical records were analyzed, i.e. 498 cases, 996 former smokers and 996 never smokers. Mean age was 63.4 years (64.9% male). Smokers had higher glycosylated hemoglobin levels (7.4 vs. 7.2 and 7.2%, respectively; p=0.013) and a lower degree of metabolic control (49.2 vs. 54.7 and 55.8%; p=0.036). Smokers had higher average annual costs (EUR 3,583) than former smokers (EUR 2,885; p<0.001) and never smokers (EUR 2,183; p<0.001).

CONCLUSIONS

Diabetic smoker patients had lower metabolic control, higher health resource utilization and more sick leave, resulting in higher healthcare costs and lost productivity compared with both former and never smoker diabetics.

Evaluation of 1,5-anhydroglucitol as a marker for glycemic variability in patients with type 2 diabetes mellitus

1,5-anhydroglucitol (1,5-AG) has been suggested as a marker for short-term glycemic control and postprandial hyperglycemia. However, the role of 1,5-AG in glycemic variability has not been established. The aim of this study was to demonstrate the usefulness of 1,5-AG as a marker for glycemic variability in patients with type 2 diabetes. Sixty patients with type 2 diabetes were enrolled, and a continuous glucose monitoring system (CGMS) was applied for 72 h. Continuous overlapping net glycemic action (CONGA), mean amplitude of glycemic excursion (MAGE), and mean of the daily differences (MODD) were calculated for the assessment of glycemic variability and compared with 1,5-AG. Urinary 8-iso prostaglandin F2α (8-isoPGF2α) was measured to assess oxidative stress. 1,5-AG was correlated with fasting blood glucose, HbA1c, postprandial area under the curve for glucose above 180 mg/dL (AUC-180), and mean post-meal maximum glucose (MPMG). However, 1,5-AG did not show significant correlation with CONGA-1, MAGE, and MODD (R = -0.053, P = 0.689; R = -0.148, P = 0.259; R = -0.123, P = 0.350). In patients with HbA1c ≤ 8.0% (n = 35), 1,5-AG was significantly correlated with HbA1c, mean glucose, postprandial AUC-180, and MPMG. However, in patients with HbA1c > 8.0% (n = 25), 1,5-AG did not show correlation with any glycemic markers. Oxidative stress measured as urine 8-isoPGF2α showed positive correlations with CONGA-1, MAGE, AUC-180, postprandial AUC-180, and MPMG only in men. However, 1,5-AG did not correlate with oxidative stress. Our data suggested a limited usefulness of 1,5-AG in estimating glycemic variability and oxidative stress. 1,5-AG was able to represent mean glucose and postprandial hyperglycemia only in well-controlled diabetic patients.

The importance of HbA1c and glucose variability in patients with type 1 and type 2 diabetes: outcome of continuous glucose monitoring (CGM)

Glucose variability has recently been investigated in diabetic patients in several studies, but most of them considered only a few variability indicators and did not systematically correlate them with patients' HbA1c levels and other important characteristics. In thus study, the correlations between HbA1c levels and metabolic control (average glucose, AG), glucose variability (SD, CONGA, MAGE, MODD, BG ROC), hyperglycemia (HBGI), hypoglycemia (LBGI) and postprandial (AUC PP) indices were investigated in patients with type 1 and type 2 diabetes. The study involved 68 patients divided into 3 groups as follows: 35 patients had type 1 diabetes (group 1); 17 had type 2 diabetes and were taking multiple daily injections (MDI) of insulin (group 2); and 16 patients had type 2 diabetes treated with OHA and/or basal insulin (group 3). The indicators were obtained over at least 48 h using a continuous glucose monitoring (CGM) system. HbA1c levels were measured at the baseline and after CGM. HbA1c correlated significantly with AG (r = 0.74), AUC PP (r = 0.69) and HBGI (r = 0.74), but only in type 1 diabetic patients. Patients with longstanding disease and type 1 diabetes had a greater glucose variability, irrespective of their HbA1c levels. Insulin therapy with MDI correlated strongly with HbA1c, but not with glucose variability. HbA1c levels identify states of sustained hyperglycemia and seem to be unaffected by hypoglycemic episodes or short-lived glucose spikes, consequently revealing shortcomings as a "gold standard" indicator of metabolic control. Glucose variability indicators describe the glucose profile of type 1 diabetic patients and identify any worsening glycemic control (typical of longstanding diabetes) more accurately than HbA1c tests.

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.

The glycated albumin to glycated haemoglobin ratio increases along with the fibrosis stage in non-alcoholic steatohepatitis

BACKGROUND

We previously reported that the indicator of glycaemic control, glycated albumin (GA) levels, are low in relation to glycaemia in patients with high alanine aminotransferase (ALT) levels in non-alcoholic fatty liver disease because of chronic inflammation, and that the GA/glycated haemoglobin ratio (G/H ratio) is inversely correlated with hepatic function in patients with chronic liver disease. The severity of liver fibrosis is known to be a good indicator for surveillance, and for determining the prognosis and optimal treatment of non-alcoholic steatohepatitis (NASH). In this study, we aimed to investigate the clinical usefulness of measuring the G/H ratio for predicting the severity of liver fibrosis in patients with NASH.

METHODS

The study subjects were 36 patients with histologically diagnosed NASH (19 men, 17 women; mean age 54.8±12.2 years, body mass index 28.3±5.0 kg/m2). The relationships of the G/H ratio to hepatic function tests and fibrosis stage in the liver were investigated.

RESULTS

The G/H ratio in patients with NASH was inversely correlated with ALT (P<0.001) and platelet count (P<0.0001). Furthermore, the G/H ratio was positively correlated with the fibrosis stage in liver (P=0.003).

CONCLUSIONS

These results suggest that the G/H ratio increases along with the fibrosis stage in patients with NASH.

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.

Glycated hemoglobin A₁c (HbA₁c) and diabetes: a new era?

Abstract In January 2011 the American Diabetes Association (ADA) published the latest guidelines for the diagnosis and treatment of diabetes mellitus (DM)(1,2). Despite some controversies, glycated hemoglobin A(1c) (HbA(1c)), an established marker of long-term glycemia traditionally used to assess the quality of DM management, remained an independent criterion for the diagnosis of DM, and indeed now appears to be well established in the USA. This has far-reaching implications for clinical practice worldwide.

Glycated albumin is a useful glycation index for monitoring fluctuating and poorly controlled type 2 diabetic patients

Glycated albumin (GA) is recognized as a reliable marker for short-term glycemic monitoring in diabetic patients. We investigated the clinical relevance of GA and the ratio of GA to glycated hemoglobin (A1c) in Korean type 2 diabetic patients. In this retrospective study, we compared A1c, GA, and the GA/A1c ratio and analyzed the relationship between glycemic indices and various parameters in 1,038 Korean type 2 diabetic patients. The patients were divided into two groups: a stably maintained A1c group whose A1c levels did not fluctuate by more than 0.5% for at least 6 months and an unstably maintained A1c group whose A1c levels fluctuated by more than 0.5%. Serum GA was strongly correlated with A1c in both groups. Fasting plasma glucose and postprandial glucose were correlated with GA in unstably maintained A1c group, whereas they were correlated with A1c in stably maintained A1c group. The GA/A1c ratio tended to increase as A1c increased. Postprandial glucose and body mass index affected the GA/A1c ratio. Our data show that serum GA may be a more useful glycation index than A1c for monitoring glycemic control in type 2 diabetic patients with fluctuating and poorly controlled glycemic excursions.

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.

The glycation of albumin: structural and functional impacts

Oxidative stress and protein modifications are frequently observed in numerous disease states. Glucose constitutes a vital nutrient necessary to cellular oxygen metabolism. However, hyperglycemia-associated damage is an important factor in diabetes disorders. Albumin, the major circulating protein in blood, can undergo increased glycation in diabetes. From recent studies, it has become evident that protein glycation has important implications for protein activity, unfolding, and degradation, as well as for cell functioning. After giving a brief overview of the key role of albumin in overall antioxidant defense, this review examines its role as a target of glycation reactions. A synthesis of state of the art methods for measuring and characterizing albumin glycation is detailed. In light of recent data, we then report the impact of glycation on the structure of albumin and its various activities, especially its antioxidant and binding capacities. The biological impact of glycated albumin on cell physiology is also discussed, specifically the role of the protein as a biological marker of diabetes.

Serum glycated albumin, but not glycated haemoglobin, is low in relation to glycemia in hyperuricemic men

Measurements of glycated albumin (GA) as well as glycated haemoglobin (HbA(1C)) have been applied in order to monitor chronic glycemic control in diabetic patients. Since the levels of both glycated proteins are influenced by various factors other than glycemia, cautions are necessary to evaluate such measures in some specific conditions. In this study, we examined the effects of serum uric acid (UA) levels on these glycemic markers. One hundred and ninety-three men with normal glucose tolerance were enrolled in this study. Association of serum UA with BMI, plasma glucose (PG), high sensitivity CRP (hs-CRP), serum GA and HbA(1C) was analysed. Serum UA showed a significant positive correlation with BMI (R = 0.329, P < 0.0001) and hs-CRP (R = 0.306, P < 0.0001). Multivariate analysis revealed serum UA to be a significant positive explanatory variable for hs-CRP. There was a significant positive correlation of serum UA with the 2-h PG after 75 g OGTT but not fasting PG. Although there was no correlation of serum UA with HbA(1C), serum UA showed a significant inverse correlation with both serum GA (R = -0.402, P < 0.0001) as well as BMI-adjusted serum GA (R = -0.327, P < 0.0001). By multivariate analysis, serum UA was an explanatory variable for serum GA. Serum GA, but not HbA(1C), is set lower in relation to plasma glucose levels in hyperglycemic men. This may be caused by microinflammation associated with hyperuricemic state.

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.