An enzymatic method for the measurement of glycated albumin in biological samples

Association of fasting serum insulin and fasting serum glucose levels with cognitive impairment in Chinese nonagenarians/centenarians

In this study, we examined the association of fasting serum insulin (FSI) and fasting serum glucose (FSG) with cognitive impairment in the very elderly using a sample of Chinese nonagenarians/centenarians. This study used data from a survey that was conducted in 2005 on all residents aged 90 years or more in a district with 2,311,709 inhabitants. FSG, FSI, and cognitive function were analyzed. The sample included 661 unrelated Chinese individuals (aged 90-108 years; mean, 93.52 ± 3.37 years; 67.17 % women; FSI, 6.27 ± 2.27 mU/mL; FSG levels, 4.46 ± 1.45 mmol/L). The prevalence of cognitive impairment was 61.81 % and that of hypoinsulinemia was 31.92 %. Individuals with hypoinsulinemia showed lower cognitive function scores (14.81 ± 5.79 vs. 15.78 ± 5.24, t = 2.160, P = 0.031). No differences in cognitive function score between different FSI and FSG groups were significant, and no differences in FSI and FSG between individuals with and without cognitive impairment were statistically significant. Unadjusted multiple logistic regressions showed that hypoinsulinemia, impaired fasting glucose, or diabetes did not change the risk of cognitive impairment significantly. In summary, we found that in elderly subjects, cognitive function appeared associated with FSI, and higher FSI may be associated with enhanced cognitive function.

Evaluation of glycated hemoglobin and fetal hemoglobin-adjusted HbA1c measurements in infants

BACKGROUND

As the presence of fetal hemoglobin (HbF) affects the accuracy of hemoglobin A1c (HbA1c) analysis methods, HbA1c measurement may not be a good indicator for patients with neonatal diabetes mellitus, whereas glycated albumin (GA) may be a good indicator.

OBJECTIVE

To investigate whether total glycated hemoglobin (GHb) or HbF-adjusted HbA1c (adj-HbA1c) can act as a glycemic control marker in infants.

SUBJECTS AND METHODS

Plasma glucose (PG), GA, HbF, GHb measured using the affinity method, and HbA1c measured using the latex-immunoturbidimetry (LA) or the high-performance liquid chromatography (HPLC) methods were determined in 26 full-term newborn infants aged 4-234 d. Adj-HbA1c was calculated as HbA1c/(total Hb - HbF).

RESULTS

GHb, adj-HbA1c measured using the LA and the HPLC methods were 4.8 ± 0.5%, 4.5 ± 0.5%, and 4.7 ± 0.6%, respectively. GA was most positively correlated with PG (r = 0.696, p < 0.0001). GHb was positively correlated with both PG (r = 0.479, p = 0.013) and GA (r = 0.727, p < 0.0001). Adj-HbA1c measured using the LA method was positively correlated with GA (r = 0.465, p = 0.017), but not PG (r = 0.304, p = 0.132). Adj-HbA1c measured using the HPLC method was correlated with neither PG (r = -0.077, p = 0.710) nor GA (r = 0.360, p = 0.071).

CONCLUSIONS

GHb measured using the affinity method may be a useful glycemic control marker in infants. Although adj-HbA1c measured using the LA method was correlated with GA, it may not be a practical measure because it was not correlated with PG and determining HbF levels using HPLC method can be troublesome. Adj-HbA1c measured using the HPLC method should not be used as a glycemic marker in infants.

Comparison of annual variability in HbA1c and glycated albumin in patients with type 1 vs. type 2 diabetes mellitus

OBJECTIVE

It has been suggested that plasma glucose (PG) levels per se and long-term variations in PG levels are associated with diabetic vascular complications. Glycated albumin (GA) reflects shorter-term glycemic control, as well as postprandial PG levels, as compared to HbA1c. In this study, we hypothesized that GA more strongly reflects long-term variations in PG levels than HbA1c, and compared the variability of HbA1c and that of GA in patients with type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM).

METHODS

This study included 8 T1DM patients and 48 T2DM patients. Over a 1-year period, HbA1c and GA were measured every month and the mean values and coefficients of variation (CV) for each patient were calculated.

RESULTS

In both T1DM and T2DM patients, the CV of GA was significantly higher than the CV of HbA1c. Both the CV of HbA1c and the CV of GA were significantly higher in the T1DM patients than in the T2DM patients.

CONCLUSION

The annual variability in GA was greater than that in HbA1c. In addition, the annual variability in HbA1c and that in GA in the T1DM patients were greater than in the T2DM patients. Our findings suggest that GA more accurately reflects long-term variations in PG levels than HbA1c.

Glycated albumin is lower in infants than in adults and correlated with both age and serum albumin

BACKGROUND

Glycated albumin (GA) reflects glycemic control in patients with neonatal diabetes mellitus (NDM). However, GA in NDM patients is apparently low in relation to glycemia.

OBJECTIVE

To establish the reference intervals for GA in healthy infants.

SUBJECTS AND METHODS

Fifty-eight healthy, full-term newborn infants were used to define the GA reference values and to investigate its relationship to plasma glucose (PG) and serum albumin. The infants were categorized into three groups according to age: group A, 5 (4-6) median (range) d: n = 18; group B, 33 (30-38) d: n = 19; and group C, 181 (50-352) d: n = 21. We also studied 212 non-diabetic adults [group D, 53 (28-78) yr old] and the 5 NDM patients previously reported for GA comparisons.

RESULTS

In the infants, GA was strongly positively correlated with logarithmic transformation of age [log (age)] (p = 0.831, p < 0.0001). The GA in groups A, B, C, and D were 7.3 ± 1.0%, 8.6 ± 1.1%, 10.9 ± 0.8%, and 14.0 ± 1.1%, respectively. The GA was more strongly positively correlated with serum albumin (r = 0.768, p < 0.0001) than with PG (r = 0.596, p < 0.0001). When GA levels were compared with the age-dependent reference values, GA in the transient NDM patient was normalized although GA in the four permanent NDM patients decreased but remained high after insulin therapy.

CONCLUSIONS

This study showed that the reference range for GA in infants is lower than that of adults and increases with age, with which we confirmed that GA in the NDM patients reflected the clinical course. Consequently, GA in NDM patients should be compared with the age-based reference values to assess the accurate glycemic status.

Dipeptidyl peptidase-4 inhibitors attenuate endothelial function as evaluated by flow-mediated vasodilatation in type 2 diabetic patients

BACKGROUND

Endothelial dysfunction is an independent predictor for cardiovascular events in patients with type 2 diabetes (T2DM). Glucagon like peptide-1 (GLP-1) reportedly exerts vasodilatory actions, and inhibitors of dipeptidyl peptidase-4 (DPP-4), an enzyme-degrading GLP-1, are widely used to treat T2DM. We therefore hypothesized that DPP-4 inhibitors (DPP-4Is) improve endothelial function in T2DM patients and performed 2 prospective, randomized crossover trials to compare the DPP-4I sitagliptin and an α-glucosidase inhibitor, voglibose (in study 1) and the DPP-4Is sitagliptin and alogliptin (in study 2).

METHODS AND RESULTS

In study 1, 24 men with T2DM (46±5 years) were randomized to sitagliptin or voglibose for 6 weeks without washout periods. Surprisingly, sitagliptin significantly reduced flow-mediated vasodilatation (FMD; -51% compared with baseline, P<0.05) of the brachial artery despite improved diabetic status. In contrast, voglibose did not affect FMD. To confirm this result and determine whether it is a class effect, we conducted another trial (study 2) to compare sitagliptin and alogliptin in 42 T2DM patients (66±8 years) for 6 weeks with 4-week washout periods. Both DPP-4Is improved glycemic control but significantly attenuated FMD (7.2/4.3%, P<0.001, before/after sitagliptin; 7.0/4.8%, P<0.001, before/after alogliptin, respectively). Interestingly, FMD reduction was less evident in subjects who were on statins or whose LDL cholesterol levels were reduced by them, but this was not correlated with parameters including DPP-4 activity and GLP-1 levels or diabetic parameters.

CONCLUSIONS

Our 2 independent trials demonstrated that DPP-4 inhibition attenuated endothelial function as evaluated by FMD in T2DM patients. This unexpected unfavorable effect may be a class effect of DPP-4Is.

CLINICAL TRIAL REGISTRATION

URL: http://center.umin.ac.jp, Unique Identifiers: UMIN000005682 (sitagliptin versus voglibose) and UMIN000005681 (sitagliptin versus alogliptin).

Study on the mechanism causing elevation of serum CA19-9 levels in diabetic patients

Serum CA19-9 levels are often elevated in diabetic patients. To elucidate this mechanism, we investigated the metabolism of CA19-9 in diabetic patients without obvious cancer. Study 1 included 119 patients in whom HbA1c, glycated albumin (GA) and CA19-9 were measured at the time of hospital admission. Study 2 examined 6 patients with markedly elevated CA19-9 levels (≥100 U/mL). Their half-lives for HbA1c, GA, and serum CA19-9 were calculated using the data before and after diabetes treatment. Three diabetic patients with pancreatic cancer were also examined as controls. In Study 1, serum CA19-9 (logarithmically transformed value) was significantly correlated with fasting plasma glucose (FPG), HbA1c and GA. On multivariate analysis, GA and FPG, but not HbA1c, were significant explanatory variables for serum CA19-9. In Study 2, serum CA19-9 decreased together with HbA1c and GA after diabetes treatment. The calculated half-lives for HbA1c, GA, and serum CA19-9 were 33.8 days, 16.1 days, and 10.9 days, respectively. The half-life of serum CA19-9 was longer in the study patients than that reported in patients with malignant tumors. By contrast, in the diabetic patients with pancreatic cancer serum CA19-9 showed a marginal decrease after diabetes treatment. Taken all together, prolonged half-life of serum CA19-9 may contribute to the increase in serum CA19-9 levels in diabetic patients without obvious cancer.

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.

Biomarkers for insulin resistance and inflammation and the risk for all-cause dementia and alzheimer disease: results from the Framingham Heart Study

OBJECTIVE

To investigate the contribution of biomarkers of glucose homeostasis (adiponectin, glucose, glycated albumin, and insulin levels) and inflammation (high-sensitivity C-reactive protein and lipoprotein-associated phospholipase A(2) levels) to the risk of developing Alzheimer disease (AD) and all-cause dementia.

DESIGN

Prospective cohort study.

SETTING

Dementia-free Framingham Heart Study participants had sera measured for these biomarkers at the 19th biennial examination (1985-1988) and were followed up prospectively for the development of AD and all-cause dementia.

PARTICIPANTS

Eight hundred forty (541 women, median age of 76 years) subjects participated in the study.

MAIN OUTCOME MEASURES

We used sex-pooled and sex-specific multivariable Cox proportional hazards models adjusted for age, education, body mass index, recent change in weight, APOE ε4 allele status, and plasma docosahexaenoic acid levels to determine association of these biomarkers with the development of all-cause dementia and AD.

RESULTS

Over a mean follow-up period of 13 years, 159 persons developed dementia (including 125 with AD). After adjustment for other risk factors, only adiponectin in women was associated with an increased risk of all-cause dementia (hazard ratio [HR], 1.29; 95% confidence interval [CI], 1.00-1.66; P=.054) and AD (HR, 1.33; 95% CI, 1.00-1.76; P=.050) per 1-SD increase in adiponectin level. Women with baseline adiponectin values more than the median had a higher risk of all-cause dementia (HR, 1.63; 95% CI, 1.03-2.56; P=.04) and AD (HR, 1.87; 95% CI, 1.13-3.10; P=.01) as compared with those with values less than the median.

CONCLUSION

In women, increased plasma adiponectin levels are an independent risk factor for the development of both all-cause dementia and AD.

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.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

Effects of 14-Week Tai Ji Quan Exercise on Metabolic Control in Women with Type 2 Diabetes

The present study investigated the effects of 14 weeks of practicing Tai Ji Quan (TJQ) on metabolic control and lipid metabolism in women with type 2 diabetes. Twenty Beijing female residents (57.4 ± 6.2 years) were recruited and were randomly assigned to either the TJQ training or the control group. In the TJQ group, the exercise duration was 1 hour per day and 5 days a week for 14 weeks. FPG, GSP, FPI, TC, HDL-C, LDL-C, TG, resting blood pressures and heart rate were measured before and after the 14 weeks in the 2 groups. It was found that after 14 weeks, the TJQ group had significantly lower FPG, GSP, TG and higher FPI concentration, whereas there were no significant differences in TC, HDL-C and LDL-C. It was concluded that TJQ exercise could be used as an intervention tool to improve glycaemic control and serum TG level in the elderly people. Future research with TJQ of different styles and exercise of different intensities were recommended.

Estimation of Duration of Symptoms in Fulminant Type 1 Diabetes Mellitus Using HbA1c or Glycated Albumin

Fulminant type 1 diabetes mellitus (FT1DM) develops as a result of very rapid and almost complete destruction of pancreatic β cells. Because of an abrupt increase in plasma glucose, HbA_1c and glycated albumin (GA) might increase along with duration of symptoms in FT1DM patients. We attempted to devise a formula to estimate duration of symptoms based on the increased levels in HbA_1c or GA. Four patients who developed FT1DM during the course of type 2 diabetes mellitus and in whom HbA_1c was measured before onset were investigated in this study. The percents of the estimated duration of symptoms calculated from HbA_1c (four patients) and GA (two patients) to the actual duration were 137 ± 88% and 122%, respectively. In FT1DM patients in whom HbA_1c and/or GA before onset and at the time of ketoacidosis are measured, duration of symptoms might be estimated with using the increased levels in HbA_1c or GA.

Reduction in glycated albumin can predict change in HbA1c: comparison of oral hypoglycaemic agent and insulin treatments

AIM

To investigate whether the change in glycated albumin 3 weeks after initiating anti-diabetes treatment (oral hypoglycaemic agent or insulin) could predict the corresponding change in HbA(1c) 3 months later in Korean patients with Type 2 diabetes.

METHODS

A total of 140 patients were enrolled into two groups: group I (insulin-based; n = 100) and group II (oral hypoglycaemic agent-based; n = 40). Both glycated albumin and HbA(1c) levels were measured as 'glucose control markers' during hospitalization. Glycated albumin was measured again at 3 weeks (first visit) after the initial measurement, and HbA(1c) was measured at 3 months (second visit) after the initial measurement.. The change in glucose control marker was defined as 100 × (follow-up glucose control marker--hospital glucose control marker)/hospital glucose control marker.

RESULTS

In both groups, the change in glycated albumin at the first visit and in HbA(1c) at the second visit showed a moderate linear relationship (r = 0.735; P < 0.01). In group II (r = 0.778; P < 0.01), a slightly stronger linear relationship was demonstrated than in group I (r = 0.738; P < 0.001); however, there was no statistically significant difference between the two groups. A correlation coefficient between the change in glycated albumin and HbA(1c) was not affected by sex, age, BMI, haemoglobin, serum creatinine or albumin.

CONCLUSION

The reduction in glycated albumin 3 weeks after the initiation of treatment corresponded with the reduction in HbA(1c) 3 months after starting treatment in both the group treated with a oral hypoglycaemic agent and the insulin-treated group of Korean patients with Type 2 diabetes.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Emerging applications of metabolomic and genomic profiling in diabetic clinical medicine

Clinical and epidemiological metabolomics provides a unique opportunity to look at genotype-phenotype relationships as well as the body\x{2019}s responses to environmental and lifestyle factors. Fundamentally, it provides information on the universal outcome of influencing factors on disease states and has great potential in the early diagnosis, therapy monitoring, and understanding of the pathogenesis of disease. Diseases, such as diabetes, with a complex set of interactions between genetic and environmental factors, produce changes in the body\x{2019}s biochemical profile, thereby providing potential markers for diagnosis and initiation of therapies. There is clearly a need to discover new ways to aid diagnosis and assessment of glycemic status to help reduce diabetes complications and improve the quality of life. Many factors, including peptides, proteins, metabolites, nucleic acids, and polymorphisms, have been proposed as putative biomarkers for diabetes. Metabolomics is an approach used to identify and assess metabolic characteristics, changes, and phenotypes in response to influencing factors, such as environment, diet, lifestyle, and pathophysiological states. The specificity and sensitivity using metabolomics to identify biomarkers of disease have become increasingly feasible because of advances in analytical and information technologies. Likewise, the emergence of high-throughput genotyping technologies and genome-wide association studies has prompted the search for genetic markers of diabetes predisposition or susceptibility. In this review, we consider the application of key metabolomic and genomic methodologies in diabetes and summarize the established, new, and emerging metabolomic and genomic biomarkers for the disease. We conclude by summarizing future insights into the search for improved biomarkers for diabetes research and human diagnostics.

Utility of glycated albumin for the diagnosis of diabetes mellitus in a Japanese population study: results from the Kyushu and Okinawa Population Study (KOPS)

AIMS/HYPOTHESIS

Glycated albumin is a measure of the mean plasma glucose concentration over approximately 2-3 weeks. We determined reference values for glycated albumin, and assessed its utility for the diagnosis of type 2 diabetes mellitus in the general population.

METHODS

We studied 1,575 men and women (mean age, 49.9 years; range, 26-78 years) who participated in a periodic health examination in a suburban Japanese town. HbA(1c) and fasting plasma concentrations of glucose (FPG) and glycated albumin were measured. Participants with FPG ≥ 7.0 mmol/l or HbA(1c) ≥ 6.5% (48 mmol/mol) were diagnosed as having diabetes. In our laboratory, the glycated albumin assay had intra-assay and inter-assay CVs of 1.1% and 1.6%, respectively.

RESULTS

Glycated albumin levels were significantly correlated with HbA(1c) levels (r = 0.766, p < 0.001) and FPG (r = 0.706, p < 0.001). The presence of diabetes was significantly higher in participants with glycated albumin levels between 15.0% and 15.9% (five of 276, 1.81%) than in those with glycated albumin <14% (three of 672, 0.45%) (p = 0.037), and was markedly increased in those with a glycated albumin level >16% (58 of 207, 28.0%). Receiver operating characteristic curve analysis indicated that a glycated albumin level of ≥15.5% was optimal for predicting diabetes, with a sensitivity of 83.3% and a specificity of 83.3%.

CONCLUSIONS/INTERPRETATION

There is merit to further investigating the potential for glycated albumin to be used as an alternative measure of dysglycaemia for future research and clinical practice.

Construction of engineered fructosyl peptidyl oxidase for enzyme sensor applications under normal atmospheric conditions

Current enzymatic methods for the analysis of glycated proteins use flavoenzymes that catalyze the oxidative deglycation of fructosyl peptides, designated as fructosyl peptidyl oxidases (FPOXs). However, as FPOXs are oxidases, the signals derived from electron mediator-type electrochemical monitoring based on them are affected by dissolved O(2). Improvement of dye-mediated dehydrogenase activity of FPOXs and its application to enzyme electrode construction were therefore undertaken. Saturation mutagenesis study on Asn56 of FPOX from Phaeosphaeria nodorum, produced mutants with marked decreases in the catalytic ability to employ O(2) as the electron acceptor, while showing higher dye-mediated dehydrogenase activity employing artificial electron acceptors than the parental enzyme. Thus constructed virtually fructosyl peptide dehydrogenase, Asn56Ala, was then applied to produce an enzyme electrode for the measurement of fructosyl-(α) N-valyl-histidine (f-(α)Val-His), the protease-digested product of HbA1c. The enzyme electrode could measure f-(α)Val-His in the physiological target range in air.

Basic performance of an enzymatic method for glycated albumin and reference range determination

BACKGROUND

Glycated albumin (GA) is a medium-term glycemic control marker of diabetes and may be more sensitive to changes in plasma glucose than hemoglobin A1c. We studied where and how many fructosyl groups bind to albumin, and which glycation sites are measured by the enzymatic method for GA. We also studied the basic performance of the enzymatic method for GA.

METHODS

Glycated albumin was measured using an enzymatic method (Lucica®GA-L, Asahi Kasei Pharma) on a biochemical autoanalyzer. Molecular weights of purified GA and nonglycated albumin were measured by a mass spectrometry system. Two hundred one healthy volunteers with normal results of oral glucose tolerance testing were recruited to determine the reference range in Americans.

RESULTS

The present method measured only glycated amino acids from albumin in serum protein. We estimate that the number of glycated amino acids measured by this method was approximately two per molecule of albumin. The general performance (sensitivity, specificity, reproducibility, linearity, interference) of the method was good. The reference range of GA% in Americans with normal glucose tolerance was determined to be 11.9-15.8% (mean ± 2 standard deviations). Significant differences were not observed between the sexes; however, race differences were observed (higher levels in blacks relative to whites).

CONCLUSIONS

The method was specific for measuring glycated amino acids in albumin and had good basic performance characteristics. The reference range in Americans was 11.9-15.8%. This method may be a useful indicator for diabetes control.

Glycated albumin levels are higher relative to HbA1c levels in people with autoimmune acute-onset type 1 diabetes mellitus than in people with type 2 diabetes mellitus at the time of diagnosis

Glycated albumin (GA) is a new glycemic control indicator. GA/HbA1c ratio in autoimmune acute-onset type 1 diabetes mellitus patients was significantly higher than in type 2 diabetes mellitus patients at the time of diagnosis. This difference might reflect speed of increase in plasma glucose after the onset of diabetes.

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

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

Glycated albumin but not HbA1c reflects glycaemic control in patients with neonatal diabetes mellitus

AIMS/HYPOTHESIS

It is difficult to use HbA(1c) as an indicator of glycaemic control in patients with neonatal diabetes mellitus (NDM) because of high levels of fetal haemoglobin (HbF) remaining in the blood. In this study, glycated albumin (GA), which is not affected by HbF, and HbA(1c) were compared to evaluate whether they reflect glycaemic control in patients with NDM.

METHODS

This study included five patients with NDM. Age at diagnosis was 38 ± 20 days. Insulin therapy was started in all patients, and levels of GA, HbA(1c) and HbF were measured monthly for 6 months. One-month average preprandial plasma glucose (aPPG) was calculated using self-monitoring of blood glucose.

RESULTS

Plasma glucose and GA were elevated (29.7 ± 13.1 mmol/l [n = 5] and 33.3 ± 6.9% [n = 3], respectively) but HbA(1c) was within normal limits (5.4 ± 2.6% [35.5 ± 4.9 mmol/mol]; n = 4) at diagnosis. With diabetes treatment, aPPG (r = -0.565, p = 0.002), GA (r = -0.552, p = 0.003) and HbF (r = -0.855, p < 0.0001) decreased with age, whereas HbA(1c) increased (r = 0.449, p = 0.004). GA was strongly positively correlated with aPPG (r = 0.784, p < 0.0001), while HbA(1c) showed no correlation with aPPG (r = 0.221, p = 0.257) and was significantly inversely correlated with HbF (r = -0.539, p = 0.004).

CONCLUSIONS/INTERPRETATION

GA is a useful indicator of glycaemic control in patients with NDM, whereas HbA(1c) is influenced by age-related changes in HbF and does not accurately reflect glycaemic control.

Metabolic responses to prolonged consumption of glucose- and fructose-sweetened beverages are not associated with postprandial or 24-h glucose and insulin excursions

BACKGROUND

Consumption of sugar-sweetened beverages has been shown to be associated with dyslipidemia, insulin resistance, fatty liver, diabetes, and cardiovascular disease. It has been proposed that adverse metabolic effects of chronic consumption of sugar-sweetened beverages are a consequence of increased circulating glucose and insulin excursions, ie, dietary glycemic index (GI).

OBJECTIVE

We determined whether the greater adverse effects of fructose than of glucose consumption were associated with glucose and insulin exposures.

DESIGN

The subjects were studied in a metabolic facility and consumed energy-balanced diets containing 55% of energy as complex carbohydrate for 2 wk (GI = 64). The subjects then consumed 25% of energy requirements as fructose- or glucose-sweetened beverages along with their usual ad libitum diets for 8 wk at home and then as part of energy-balanced diets for 2 wk at the metabolic facility (fructose GI = 38, glucose GI = 83). The 24-h glucose and insulin profiles and fasting plasma glycated albumin and fructosamine concentrations were measured 0, 2, 8, and 10 wk after beverage consumption.

RESULTS

Consumption of fructose-sweetened beverages lowered glucose and insulin postmeal peaks and the 23-h area under the curve compared with the baseline diet and with the consumption of glucose-sweetened beverages (all P < 0.001, effect of sugar). Plasma glycated albumin concentrations were lower 10 wk after fructose than after glucose consumption (P < 0.01, effect of sugar), whereas fructosamine concentrations did not differ between groups.

CONCLUSION

The results suggest that the specific effects of fructose, but not of glucose and insulin excursions, contribute to the adverse effects of consuming sugar-sweetened beverages on lipids and insulin sensitivity. This study is registered at clinicaltrials.gov as NCT01165853.

Measurement of glycated hemoglobin and glycated albumin in umbilical cord: evaluation of the glycemic control indicators in neonates

OBJECTIVE

As neonatal blood contains a high proportion of fetal hemoglobin (HbF), it is difficult to use high-performance liquid chromatography (HPLC) method, latex-immunoturbidimetry (LA) method and enzymatic methods, which determine hemoglobin A(1C) (HbA(1C)) in order to provide the glycemic control indicators of neonates. In this study, we evaluated glycated hemoglobin (GHb) and glycated albumin (GA) as appropriate indicators of the glycemic control in the neonatal period.

STUDY DESIGN

Umbilical cord blood samples collected during delivery were subjected to measurements of GHb (HPLC methods using two different instruments, LA method, enzymatic method and affinity method) and serum GA.

RESULT

HbA(1C) levels determined by the HPLC method, the LA method and the enzymatic method were as low as <3.0% in all the cases. Although GHb determined by the affinity method was 3.6 ± 0.2%, this method may not measure accurately the values of glycated HbF plus glycated HbA. Serum GA was 9.4 ± 1.1%.

CONCLUSION

We speculate that serum GA, but not GHb, could be used as glycemic control indicators in neonates.

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.

Effects of maximal atorvastatin and rosuvastatin treatment on markers of glucose homeostasis and inflammation

Studies have reported an increased risk of developing diabetes in subjects receiving statins versus placebo. Our purpose was to compare the effects of maximum doses of rosuvastatin and atorvastatin on the plasma levels of the insulin, glycated albumin, adiponectin, and C-reactive protein compared to baseline in hyperlipidemic patients. We studied 252 hyperlipidemic men and women who had been randomized to receive atorvastatin 80 mg/day or rosuvastatin 40 mg/day during a 6-week period. Atorvastatin and rosuvastatin were both highly effective in lowering the low-density lipoprotein cholesterol and triglyceride levels, with rosuvastatin more effective than atorvastatin in increasing high-density lipoprotein cholesterol. Atorvastatin and rosuvastatin at the maximum dosage both significantly (p <0.05) increased the median insulin levels by 5.2% and 8.7%, respectively, from baseline. However, only atorvastatin increased the glycated albumin levels from baseline (+0.8% for atorvastatin vs -0.7% for rosuvastatin, p = 0.002). Both atorvastatin and rosuvastatin caused significant (p <0.001) and similar median reductions in the C-reactive protein level of -40% and -26% compared to the baseline values. However, no statistically significant difference was found between the 2 groups in the adiponectin changes from baseline (-1.5% vs -4.9%, p = 0.15). In conclusion, our data have indicated that the maximum dosage of atorvastatin or rosuvastatin therapy significantly lower C-reactive protein levels but also moderately increase insulin levels.

Comparison of modification sites formed on human serum albumin at various stages of glycation

BACKGROUND

Many of the complications encountered during diabetes can be linked to the non-enzymatic glycation of proteins, including human serum albumin (HSA). However, there is little information regarding how the glycation pattern of HSA changes as the total extent of glycation is varied. The goal of this study was to identify and conduct a semi-quantitative comparison of the glycation products on HSA that are produced in the presence of various levels of glycation.

METHODS

Three glycated HSA samples were prepared in vitro by incubating physiological concentrations of HSA with 15 mmol/l glucose for 2 or 5 weeks, or with 30 mmol/l glucose for 4 weeks. These samples were then digested and examined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the glycation products that were formed.

RESULTS

It was found that the glycation pattern of HSA changed with its overall extent of total glycation. Many modifications including previously-reported primary glycation sites (e.g., K199, K281, and the N-terminus) were consistently found in the tested samples. Lysines 199 and 281, as well as arginine 428, contained the most consistently identified and abundant glycation products. Lysines 93, 276, 286, 414, 439, and 524/525, as well as the N-terminus and arginines 98, 197, and 521, were also found to be modified at various degrees of HSA glycation.

CONCLUSIONS

The glycation pattern of HSA was found to vary with different levels of total glycation and included modifications at the 2 major drug binding sites on this protein. This result suggests that different modified forms of HSA, both in terms of the total extent of glycation and glycation pattern, may be found at various stages of diabetes. The clinical implication of these results is that the binding of HSA to some drug may be altered at various stages of diabetes as the extent of glycation and types of modifications in this protein are varied.

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.

Influence of iron metabolism indices on glycated haemoglobin but not glycated albumin levels in premenopausal women

We have recently shown that in premenopausal women without anaemia, glycated haemoglobin (HbA(1C)) is inversely associated with mean corpuscular haemoglobin (MCH). Based on the hypothesis that iron deficient state (IDS) due to menstruation may influence erythrocyte metabolism and thereby HbA(1C) levels, we examined the relation of iron metabolism indices with HbA(1C) in premenopausal women. HbA(1C), serum glycated albumin (GA) and iron metabolism indices were determined in 104 premenopausal women with normal glucose tolerance. Among them, 17 were diagnosed with iron deficiency anaemia (IDA) and 30 with IDS. The other 57 subjects were diagnosed with normal iron state (NIS). HbA(1C) levels showed significant inverse association with serum iron, serum transferrin saturation and serum ferritin in 104 study participants. Multivariate regression analysis identified serum ferritin as negatively associated with HbA(1C). These were also observed in 87 premenopausal women without IDA. HbA(1C) levels in IDA subjects and in IDS subjects were higher than it in NIS subjects, while GA levels were not different among the three groups of subjects. In conclusions, iron metabolism indices influence HbA(1C) levels, but not serum GA levels, in premenopausal women.

Evaluation of error levels in hemoglobin A1c and glycated albumin in type 2 diabetic patients due to inter-individual variability

AIM

To evaluate error levels in hemoglobin A1c (A1C) and glycated albumin (GA) in type 2 diabetic patients due to inter-individual variability.

METHODS

Type 2 diabetic patients with stable glycemic control and without complications affecting either A1C or GA were enrolled (n=154; age 68.4+/-9.9 years). Blood examination was performed 1-4h after breakfast or lunch every 2-3 months on > or =3 occasions. A1C data were changed to IFCC values for analysis.

RESULTS

A1C and GA correlated significantly with postprandial plasma glucose. The correlation coefficient between A1C and GA was 0.728 (p<0.001) when calculated using raw data and 0.747 (p<0.001) when calculated using averaged data for each patient. The ratio R of GA to A1C was 3.88+/-0.50 for raw data and 3.88+/-0.47 for averaged data, indicating coefficients of variation of R (CV(R)) of 12.9% and 12.1%, respectively. Multiple regression analysis reduced CV(R) to 11.2%. After dividing CV(R)(2) into CV(A1C)(2) and CV(GA)(2), CV(A1C) and CV(GA) were calculated as 9.1% for raw data and 8.6% for averaged data, and were reduced to 7.9% after multiple regression analysis.

CONCLUSIONS

Error levels in A1C and GA reach 7.9-9.1%, suggesting the existence of maximal 18% errors in A1C and GA levels.

Thioredoxin glycation: A novel posttranslational modification that inhibits its antioxidant and organ protective actions

Thioredoxin (Trx) is an antioxidant and antiapoptotic molecule, and its activity is regulated by posttranslational modifications. Trx-1 has recently been reported to exert potent protective action against endotoxic liver injury. However, whether Trx-1 activity is affected by endotoxin has never been previously investigated. The aim of the present study was to determine endotoxic regulation of Trx-1, and the potential mechanism involved. In vitro coincubation of Trx-1 with lipopolysaccharide (LPS) inhibited Trx-1 activity in a dose- and time-dependent fashion. The core (polysaccharide containing) region of LPS had a greater inhibitory effect on Trx-1 activity than its Lipid A fragment, suggesting the involvement of sugar groups. Periodic acid-Schiff staining and fructosamine assay demonstrated that Trx-1 was rapidly glycated by LPS. Aminoguanidine, a competitive glycation-inhibitor, completely blocked the inhibitory effect of LPS on Trx-1. Moreover, Trx-1 activity was also significantly inhibited by in vitro ribose incubation. Finally, in vivo administration of Trx-1, but not glycated Trx-1, reduced LPS-induced hepatic injury. Taken together, these results demonstrated for the first time that Trx-1 is susceptible to glycative inactivation. This novel posttranslational Trx-1 modification contributes to LPS cytotoxicity, suggesting that blockading protein glycation might be a new therapeutic strategy against endotoxic organ injury.

Serum glycated albumin to haemoglobin A(1C) ratio can distinguish fulminant type 1 diabetes mellitus from type 2 diabetes mellitus

BACKGROUND

Fulminant type 1 diabetes mellitus (FT1DM), a subtype of type 1 diabetes mellitus, was first reported as a disease entity in 2000. Ketoacidosis at initial onset due to acute pancreatic cell destruction makes early diagnosis and treatment for FT1DM mandatory. In the early period of FT1DM, haemoglobin (Hb)A(1C) levels are not markedly elevated. This study investigated serum glycated albumin (GA), which reflects acute short-term changes in plasma glucose, as a new clinical index for FT1DM at disease onset.

METHODS

Subjects comprised 35 patients with FT1DM who had undergone measurement of HbA(1C) and serum GA at initial visit and 42 patients with type 2 diabetes mellitus (T2DM) with HbA(1C) <8.5% and no history of diabetes treatment as controls.

RESULTS

HbA(1C) was significantly lower in FT1DM than in T2DM, whereas serum GA was significantly higher. GA/HbA(1C) ratio was thus significantly higher in FT1DM than in T2DM (3.9 +/- 0.5 versus 2.8 +/- 0.3; P < 0.0001). GA/HbA(1C) ratio was >3.2 in 41 of 42 FT1DM patients (98%), compared with only one of 32 T2DM patients (3%).

CONCLUSIONS

Serum GA is significantly higher in FT1DM than in T2DM, whereas HbA(1C) is significantly lower. FT1DM can thus be distinguished from untreated T2DM by GA/HbA(1C) ratio at initial visit before treatment for 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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A1C but not serum glycated albumin is elevated because of iron deficiency in late pregnancy in diabetic women

OBJECTIVE We have already reported that A1C is elevated because of iron deficiency in late pregnancy among nondiabetic pregnant women. This report examined whether the same phenomenon is observed in pregnant women with diabetes. RESEARCH DESIGN AND METHODS This longitudinal study was conducted in 17 pregnant women with diabetes (20-35 weeks of pregnancy). A1C, serum glycated albumin, erythrocyte indexes, and iron metabolism indexes were measured. RESULTS A1C levels were significantly increased in late pregnancy, whereas serum glycated albumin showed no significant changes. Glycated albumin/A1C ratio, mean corpuscular hemoglobin, serum transferrin saturation, and serum ferritin were significantly decreased in late pregnancy. Serum transferrin saturation showed a significant positive correlation with glycated albumin/A1C ratio. CONCLUSIONS A1C levels, but not serum glycated albumin levels, are elevated in late pregnancy because of iron deficiency in diabetic women. Serum glycated albumin may offer an adequate marker for glycemic control during pregnancy.

Relationship between clinical markers of glycemia and glucose excursion evaluated by continuous glucose monitoring (CGM)

In order to evaluate the relationship between clinical markers of glycemia and glucose excursion, we performed 48-hour continuous glucose monitoring (CGM) in 43 diabetic patients. For the clinical markers, HbA(1c), glycoalbumin (GA), and 1,5-anhydroglucitol (1,5-AG) were measured, and for the parameters of glucose excursion from CGM, average glucose (AG), standard deviation of glucose (SD), the area under the curve for glucose levels >180 mg/dL (AUC(>180)), and the difference between the maximum and minimum glucose levels during 48 hours (DeltaG(48hr)) were analyzed. All patients were treated without any changes of the dosages of oral anti-diabetic agents or insulin for at least the previous 3 months with coefficient of variation (CV) of HbA(1c) less than 4 %. In results, while HbA(1c) did not show any single correlation with AG, SD, AUC(>180), or DeltaG(48hr), both GA and 1,5-AG were significantly related to all these parameters. Furthermore, GA significantly correlated to all CGM parameters, and SD significantly correlated to GA in multiple regression analyses. These results suggest that GA may be a different marker from HbA(1c) for diabetic complications, because GA, but not HbA(1c), may reflect not only short-term average glucose but also fluctuation of glucose.

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.

Altering dietary lysine:arginine ratio has little effect on cardiovascular risk factors and vascular reactivity in moderately hypercholesterolemic adults

BACKGROUND

Information is scarce regarding the effect of dietary protein type, with specific focus on the lysine-to-arginine (Lys:Arg) ratio, on cardiovascular risk factors and vascular reactivity in humans.

OBJECTIVE

Determine the effect of dietary Lys:Arg ratio on cardiovascular risk factors and vascular reactivity in moderately hypercholesterolemic adults.

DESIGN

Randomized cross-over design of two 35-day diet phases; thirty adults (21 females and 9 males, >or=50 years, LDL cholesterol>or=120 mg/dL). Diets had 20% energy (E) protein, 30%E fat, 50%E carbohydrate and were designed to have low (0.7) or high (1.4) Lys:Arg ratio. Measures included fasting and postprandial lipid, lipoprotein, apolipoprotein concentrations; fasting high sensitivity C-reactive protein (hsCRP), small dense LDL (sdLDL) cholesterol, remnant lipoprotein cholesterol (RemLC), glycated albumin, adiponectin and immunoreactive insulin concentrations, endogenous cholesteryl ester transfer protein (CETP) and lecithin:cholesterol acyl transferase (LCAT) activities; cholesterol fractional synthesis rate (FSR); and flow mediated dilation (FMD) and peripheral artery tonometry (PAT).

RESULTS

No differences were observed in fasting and/or postprandial total, LDL, HDL and sdLDL cholesterol, RemLC, Lp(a) or apo B concentrations, LCAT and CETP activities, FSR, glycated albumin, immunoreactive insulin, FMD or PAT. The low, relative to the high, Lys:Arg ratio diet resulted in lower postprandial VLDL cholesterol (-24%, P=0.001) and triglycerides (-23%, P=0.001), and small but significant differences in fasting (-3%, P=0.003) and postprandial (-3%, P=0.018) apo AI, and fasting adiponectin concentrations (+7%, P=0.035). Fasting and postprandial hsCRP concentrations were 23% lower after the low Lys:Arg ratio diet (P=0.020 for both).

CONCLUSIONS

Diets differing in Lys:Arg ratios had no or small effects on cardiovascular risk factors and vascular reactivity.

Glycated albumin levels are higher relative to glycated haemoglobin levels in gastrectomized subjects

Background

In gastrectomized subjects, oral glucose tolerance test often shows marked hyperglycaemia (oxyhyperglycaemia) after glucose loading. Because serum glycated albumin (GA) has been shown to better reflect postprandial and maximum plasma glucose levels, we investigated whether or not the clinical significance of serum GA and glycated haemoglobin (HbA1C) in non-diabetic gastrectomized subjects differs.

Methods

During health examinations, 62 non-diabetic subjects with a history of gastrectomy and 87 non-diabetic control subjects were selected in the present study. Body mass index (BMI) in the gastrectomy group was significantly lower than in the control group.

Results

Fasting plasma glucose levels were significantly lower in the gastrectomized subjects than in the control subjects. Although both HbA1C and serum GA were significantly higher in the gastrectomized subjects, there was a significant difference in GA/HbA1C ratio between the gastrectomized subjects and the control subjects. BMI-adjusted serum GA, based on our previous finding of inverse influence of BMI on serum GA, was also significantly higher in the gastrectomized subjects than in the controls.

Conclusions

Serum GA is higher relative to HbA1C in gastrectomized subjects. This suggests that serum GA may be a better marker than HbA1C for glycaemic excursion in these subjects.

Analysis of the method for conversion between levels of HbA1c and glycated albumin by linear regression analysis using a measurement error model

AIM

To establish a method for conversion between HbA(1c) and glycated albumin (GA) using a measurement error model (MEM).

METHODS

Type 2 diabetic patients, without complications that might affect either HbA(1c) or GA, were enrolled in the study (n=154, age 68.4+/-9.9). HbA(1c), GA and postprandial plasma glucose (PPG) levels were measured simultaneously on >or=3 occasions.

RESULTS

PPG showed a significant correlation with HbA(1c) and GA (p<0.001 for both). Correlation between HbA(1c) and GA was very high (r=0.747, p<0.001). When the independent variable was assumed to be GA, common regression analysis yielded a regression line HbA(1c)=2.59+0.204GA. When the independent variable was changed to HbA(1c), the regression line became GA=2.26+2.74HbA(1c). The y-intercept of the first line was significantly positive, whereas that of the second was not. The regression line using MEM was HbA(1c)=1.73+0.245GA. The y-intercept was 1.73+/-0.38 (p<0.001) and the slope was 0.245+/-0.018 (p<0.001), showing that 1% increase in HbA(1c) level corresponds to 4% increase in GA level.

CONCLUSIONS

The relationship between HbA(1c) and GA was examined by regression analysis using MEM. HbA(1c) levels in Japan appear to have a positive shift of approximately 1.7%. Incremental ratio 4 of GA vs. HbA(1c) showed good consistency with values derived from in vitro data.

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

Serum glycated albumin (GA) is the clinical markers reflecting recent plasma glucose levels. We have previously clarified that serum GA levels are low for obesity and chronic inflammation is involved in the obesity-associated decrease in GA levels through acceleration of albumin catabolism. The present study investigated whether smoking, which is a representative factor that increases CRP, affects serum GA levels. One hundred and three male subjects with normal glucose tolerance (70 nonsmokers, 33 smokers) were enrolled in this study. Smokers and nonsmokers displayed no significant differences in fasting plasma glucose (FPG), oral glucose tolerance test 2-h glucose and HbA(1C). CRP levels were significantly higher in smokers than in nonsmokers (P < 0.05). Serum GA levels were significantly lower in smokers than in nonsmokers (P < 0.05). Stepwise multivariate regression analysis identified FPG and age as positively associated, and BMI and smoking as negatively associated with serum GA levels. In conclusion, serum GA levels were significantly lower in smokers than in nonsmokers. Smoking was identified as a significant negative explanatory variable for serum GA levels. These findings suggest that the inflammation-induced acceleration of albumin metabolism may be involved in the mechanism by which smoking is associated with serum GA levels.

Substitution of vegetable oil for a partially-hydrogenated fat favorably alters cardiovascular disease risk factors in moderately hypercholesterolemic postmenopausal women

OBJECTIVE

Compared to vegetable oils in their unmodified state, partially-hydrogenated fat is associated with less favorable effects on cardiovascular disease (CVD) risk factors. Acceptable alternatives must be adjudicated. Our objective was to assess the effect of a recent commercial fat substitution, corn oil for partially-hydrogenated soybean oil.

METHODS

Using a double-blind cross-over design, 30 postmenopausal women >or=50 years with LDL-cholesterol concentrations >or=120 mg/dL were randomly assigned to each of two 35-day phases; all food and beverage was provided to maintain body weight. Corn or partially-hydrogenated soybean oil was incorporated throughout the diet and contributed two-thirds of fat. Primary outcomes included fasting and non-fasting lipid, lipoprotein, apolipoprotein, and fasting high sensitivity C-reactive protein (hsCRP) concentrations; secondary outcomes included fasting small dense LDL (sdLDL)-cholesterol, remnant lipoprotein cholesterol (RemLC), glycated albumin, adiponectin and immunoreactive insulin concentrations, and endogenous cholesteryl ester transfer protein (CETP) and lecithin:cholesterol acyl transferase (LCAT) activities.

RESULTS

Relative to the partially-hydrogenated soybean oil enriched diet, the corn oil enriched diet resulted in lower fasting total cholesterol (7%; P<0.0001), LDL-cholesterol (10%; P<0.0001), VLDL-cholesterol (7%; P=0.052), apo B (9%; P<0.0001), lipoprotein (a) [Lp(a)] (5%; P=0.024), sdLDL-cholesterol (17%; P=0.001), and RemLC (20%; P=0.007) concentrations, and no significant effect on the other outcomes. Changes in postprandial (4-h post-meal) lipid, lipoprotein and apolipoprotein concentrations were similar to the fasting state.

CONCLUSION

The replacement of partially-hydrogenated soybean oil with corn oil favorably affects a range of CVD risk factors and is an appropriate option to decrease cardiovascular disease risk factors in moderately hypercholesterolemic individuals.

A review of glycated albumin as an intermediate glycation index for controlling diabetes

INTRODUCTION

This article reviews glycated albumin (GA) as a potential intermediate-term glycation index to fill the gap between self-monitoring of blood glucose (SMBG) and hemoglobin A1c testing in diabetes management. The introduction gives an assessment of available short-, medium-, and long-term glycemic indicators. METHODOLOGIES AND UTILITY: Methods of GA measurement are summarized, and the variance of normal and diabetic GA values are discussed. Greatest uniformity in GA measurement is generally associated with immunoassay and the newer affinity chromatography methodologies utilized by reference laboratories. Utility of GA measurement includes its value as a marker for glycation, its substantial relationship to diabetes complications such as nephropathy and coronary artery disease, and as an unambiguous indicator of glycemic control in diabetes patients undergoing hemodialysis. Studies support the utility of GA in detecting short-term changes in glycemic control, and GA testing has been strongly recommended for gestational diabetes.

RESULTS AND DISCUSSION

The results of a survey with mailings to over 3500 diabetes care professionals primarily in the United States are outlined and analyzed (margin of error: +/-6.5%, 95% confidence). Respondents strongly supported the need for a test for intermediate glycemic control as well as the utility of a rapid GA test as a monthly glycemic indicator.

CONCLUSIONS

Such a test, as yet unavailable, could increase compliance and enhance empowerment among diabetes patients. It also has the potential to reduce the number of recommended SMBG tests, which may result in significant health care cost savings.

A1C but not serum glycated albumin is elevated in late pregnancy owing to iron deficiency

OBJECTIVE

A1C levels have been shown to be elevated in relation to glycemia in late pregnancy, although the precise mechanisms remain undetermined. We hypothesized that iron deficiency is involved in the A1C increase in late pregnancy.

RESEARCH DESIGN AND METHODS

In study 1, A1C, serum glycated albumin, erythrocyte indexes, and iron metabolism indexes were determined in 47 nondiabetic pregnant women not receiving iron supplementation who were divided into four groups according to gestational period (group I, 21-24 weeks; group II, 25-28 weeks; group III, 29-32 weeks; and group IV, 33-36 weeks). In study 2, these determinants were obtained at two gestational periods (20-23 weeks and 32-33 weeks) in 17 nondiabetic pregnant women.

RESULTS

In study 1, A1C levels were higher in groups III and IV than those in groups I and II, whereas serum glycated albumin levels were not different among these four groups. Hemoglobin, mean corpuscular hemoglobin (MCH), serum transferrin saturation, and serum ferritin were lower in groups III and IV. A1C levels were negatively correlated with MCH, serum transferrin saturation, and serum ferritin. In study 2, A1C levels were significantly increased at gestational weeks 32-33 from those at weeks 20-23, whereas serum glycated albumin levels did not differ between the two gestational periods. MCH, serum transferrin saturation, and serum ferritin were decreased at gestational weeks 32-33. A1C levels showed a negative correlation with MCH, serum transferrin saturation, and serum ferritin.

CONCLUSIONS

A1C levels were elevated in late pregnancy owing to iron deficiency. Serum glycated albumin may offer a better index for monitoring glycemic control in pregnancy.

Glycated albumin is a better indicator for glucose excursion than glycated hemoglobin in type 1 and type 2 diabetes

To determine the impact of blood glucose profile, involving fluctuation and excursion of blood glucose levels, on glycated proteins, we evaluated the association among the daily profile of blood glucose, and glycated albumin (GA) and HbA1c levels in patients with type 1 diabetes (n = 93) and type 2 diabetes (n = 75). GA levels were strongly correlated with HbA1c levels in type 1 (r = 0.85, P<0.0001) and type 2 diabetes (r = 0.61, P<0.0001), respectively. HbA1c levels were similar between patients with type 1 and type 2 diabetes, while GA levels were significantly higher in type 1 diabetes. Thus the ratio of GA levels to HbA1c levels was significantly higher in type 1 diabetes than that in type 2 diabetes (3.32 0.36 vs. 2.89 0.44, p<0.001). The degrees of GA levels and HbA1c levels correlated with maximum and mean blood glucose levels in patients with type 1 and type 2 diabetes. Stepwise multivariate analysis revealed that GA levels independently correlated with maximum blood glucose levels in type 1 diabetes (F = 43.34, P<0.001) and type 2 diabetes (F = 41.57, P<0.001). HbA1c levels also independently correlated with maximum blood glucose levels in type 1 diabetes (F = 34.78, P<0.001), as well as being correlated with mean blood glucose levels in type 2 diabetes (F = 11.28, P<0.001). In summary, GA could be a better marker for glycemic control than glycated hemoglobin in diabetic patients, especially for evaluating glycemic excursion, which is considered to be a major cause of diabetic angiopathy.