Comparing multiple measures of glycemia: how to transition from biomarker to diagnostic test?

Glycated Albumin and Adverse Clinical Outcomes in Patients With CKD: A Prospective Cohort Study

RATIONALE & OBJECTIVE

Hemoglobin A1c (HbA1c) is widely used to estimate glycemia, yet it is less reliable in patients with chronic kidney disease (CKD). There is growing interest in the complementary use of glycated albumin (GA) to improve glycemic monitoring and risk stratification. However, whether GA associates with clinical outcomes in a non-dialysis-dependent CKD population remains unknown.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

3,110 participants with CKD from the Chronic Renal Insufficiency Cohort study.

EXPOSURE

Baseline GA levels.

OUTCOME

Incident end-stage kidney disease (ESKD), cardiovascular disease (CVD) events, and all-cause mortality.

ANALYTICAL APPROACH

Cox proportional hazards regression.

RESULTS

Participant characteristics included mean age 59.0±10.8 SD years; 1,357 (43.6%) female; and 1,550 (49.8%) with diabetes. The median GA was 18.7% (IQR, 15.8%-23.3%). During an average 7.9-year follow-up, there were 980 ESKD events, 968 CVD events, and 1,084 deaths. Higher GA levels were associated with greater risks of all outcomes, regardless of diabetes status: hazard ratios for ESKD, CVD, and death among participants with the highest quartile compared with quartile 2 (reference) were 1.42 (95% CI, 1.19-1.69), 1.67 (95% CI, 1.39-2.01), and 1.63 (95% CI, 1.37-1.94), respectively. The associations with CVD and death appeared J-shaped, with increased risk also seen at the lowest GA levels. Among patients with coexisting CKD and diabetes, the associations of GA with outcomes remained significant even after adjusting for HbA1c. For each outcome, we observed a significant increase in the fraction of new prognostic information when both GA and HbA1c were added to models.

LIMITATIONS

Lack of longitudinal GA measurements; and HbA1c measurements were largely unavailable in participants without diabetes.

CONCLUSIONS

Among patients with CKD, GA levels were independently associated with risks of ESKD, CVD, and mortality, regardless of diabetes status. GA added prognostic value to HbA1c among patients with coexisting CKD and diabetes.

PLAIN-LANGUAGE SUMMARY

Hemoglobin A1c (HbA1c) is widely used to estimate glycemia, yet it is less reliable in patients with chronic kidney disease (CKD). There is growing interest in the complementary use of glycated albumin (GA) to improve glycemic monitoring and risk stratification. However, whether GA associates with clinical outcomes in a non-dialysis-dependent CKD population remains unknown. In this cohort study of 3,110 individuals with non-dialysis-dependent CKD, GA levels were independently associated with risks of end-stage kidney disease, cardiovascular disease (CVD), and mortality. The associations with CVD and mortality appeared to be J-shaped. Among patients with coexisting CKD and diabetes, GA added prognostic value to HbA1c. Thus, GA may be a valuable complementary test to HbA1c in patients with CKD.

Characterizing common and rare variations in non-traditional glycemic biomarkers using multivariate approaches on multi-ancestry ARIC study

Glycated hemoglobin, fasting glucose, glycated albumin, and fructosamine are biomarkers that reflect different aspects of the glycemic process. Genetic studies of these glycemic biomarkers can shed light on unknown aspects of type 2 diabetes genetics and biology. While there exists several GWAS of glycated hemoglobin and fasting glucose, very few GWAS have focused on glycated albumin or fructosamine. We performed a multi-phenotype GWAS of glycated albumin and fructosamine from 7,395 White and 2,016 Black participants in the Atherosclerosis Risk in Communities (ARIC) study on the common variants from genotyped/imputed data. We found 2 genome-wide significant loci, one mapping to known type 2 diabetes gene (ARAP1/STARD10, p = 2.8 × 10-8) and another mapping to a novel gene (UGT1A, p = 1.4 × 10-8) using multi-omics gene mapping strategies in diabetes-relevant tissues. We identified additional loci that were ancestry-specific (e.g., PRKCA from African ancestry individuals, p = 1.7 × 10-8) and sex-specific (TEX29 locus in males only, p = 3.0 × 10-8). Further, we implemented multi-phenotype gene-burden tests on whole-exome sequence data from 6,590 White and 2,309 Black ARIC participants. Eleven genes across different rare variant aggregation strategies were exome-wide significant only in multi-ancestry analysis. Four out of 11 genes had notable enrichment of rare predicted loss of function variants in African ancestry participants despite smaller sample size. Overall, 8 out of 15 loci/genes were implicated to influence these biomarkers via glycemic pathways. This study illustrates improved locus discovery and potential effector gene discovery by leveraging joint patterns of related biomarkers across entire allele frequency spectrum in multi-ancestry analyses. Most of the loci/genes we identified have not been previously implicated in studies of type 2 diabetes, and future investigation of the loci/genes potentially acting through glycemic pathways may help us better understand risk of developing type 2 diabetes.

Effects of Glucomannan Supplementation on Type II Diabetes Mellitus in Humans: A Meta-Analysis

The hypoglycemic and lipid-lowering effects of glucomannan are widely known, and it is a potential effective treatment for type II diabetes. In this study, we evaluated the effects of glucomannan supplementation on blood-lipid-related indicators, blood-glucose-related indicators, blood pressure (BP), and body weight (BW) in patients suffering from type II diabetes. We searched databases including PubMed, Cochrane, the comprehensive biomedical research database (Embase), Web of Science, and China National Knowledge Infrastructure (CNKI) for literature on glucomannan and type II diabetes. Six randomized controlled trials (RCTs) were eligible (n = 440 participants) to be included in our analysis. Glucomannan not only reduced the total cholesterol (TC) (MD -0.38 [95% CI: -0.61, -0.15], p = 0.001) and low-density lipoprotein (LDL) levels (MD -0.35 [95% CI: -0.52, -0.17], p < 0.0001) compared with the control group, but also reduced the fasting blood glucose (FBG) (MD -1.08 [95% CI: -1.65, -0.50], p = 0.0002), 2 h postprandial blood glucose (P2hBG) (MD -1.92 [95% CI: -3.19, -0.65], p = 0.003), fasting insulin (FINS) (MD -1.59 [95% CI: -2.69, -0.50], p = 0.004), and serum fructosamine (SFRA) levels (SMD -1.19 [95% CI: -1.74, -0.64], p < 0.0001). Our analysis indicates that glucomannan is an effective nutritional intervention for type II diabetes.

Recent Developments in Biomarkers for Diagnosis and Screening of Type 2 Diabetes Mellitus

PURPOSE OF REVIEW

Diabetes mellitus is a complex, chronic illness characterized by elevated blood glucose levels that occurs when there is cellular resistance to insulin action, pancreatic β-cells do not produce sufficient insulin, or both. Diabetes prevalence has greatly increased in recent decades; consequently, it is considered one of the fastest-growing public health emergencies globally. Poor blood glucose control can result in long-term micro- and macrovascular complications such as nephropathy, retinopathy, neuropathy, and cardiovascular disease. Individuals with diabetes require continuous medical care, including pharmacological intervention as well as lifestyle and dietary changes.

RECENT FINDINGS

The most common form of diabetes mellitus, type 2 diabetes (T2DM), represents approximately 90% of all cases worldwide. T2DM occurs more often in middle-aged and elderly adults, and its cause is multifactorial. However, its incidence has increased in children and young adults due to obesity, sedentary lifestyle, and inadequate nutrition. This high incidence is also accompanied by an estimated underdiagnosis prevalence of more than 50% worldwide. Implementing successful and cost-effective strategies for systematic screening of diabetes mellitus is imperative to ensure early detection, lowering patients' risk of developing life-threatening disease complications. Therefore, identifying new biomarkers and assay methods for diabetes mellitus to develop robust, non-invasive, painless, highly-sensitive, and precise screening techniques is essential. This review focuses on the recent development of new clinically validated and novel biomarkers as well as the methods for their determination that represent cost-effective alternatives for screening and early diagnosis of T2DM.

Associations of glycated albumin and fructosamine with glycaemic status in urban black South Africans

BACKGROUND

The associations of glycated albumin (GA) and fructosamine (FA) as alternate tests for diabetes screening in South Africans were examined to overcome shortcomings with oral glucose tolerance tests (OGTTs).

METHODS

Based on OGTTs, glycaemic status included 1) normal glucose, 2) dysglycaemia (impaired fasting glucose, impaired glucose tolerance, newly diagnosed diabetes), and 3) known diabetes.

RESULTS

Among 1092 participants, >21 years, mean GA (16.9%) and FA (230.2 μmol/l) increased significantly by age and worsening glycaemic status and were significantly higher in women vs. men and BMI (kg/m²) ≥ 30 vs. <30. For dysglycaemia, correlations of GA and FA with fasting and 2-hour glucose levels were higher in obese (0.576 to 0.688) vs. non-obese (-0.010 to 0.522). Optimal GA threshold to identify dysglycaemia was 15.35% and comparable, but with lower sensitivity (0.54) and specificity (0.55), to Asian studies. For FA, the optimal cut-point of 227.0 μmol/l approximated that described in the literature. Dysglycaemia and known diabetes were associated with GA, while only known diabetes was related to FA, in models adjusted for age, gender and obesity.

CONCLUSIONS

Potential exists for GA and/or FA as alternative measures of dysglycaemia in clinical practice in Africans, but longitudinal studies are required to clearly elucidate their utility.

Impact of genotype, body weight and sex on the prenatal muscle transcriptome of Iberian pigs

Growth is dependent on genotype and diet, even at early developmental stages. In this study, we investigated the effects of genotype, sex, and body weight on the fetal muscle transcriptome of purebred Iberian and crossbred Iberian x Large White pigs sharing the same uterine environment. RNA sequencing was performed on 16 purebred and crossbred fetuses with high body weight (340±14g and 415±14g, respectively) and 16 with low body weight (246±14g and 311±14g, respectively), on gestational day 77. Genotype had the greatest effect on gene expression, with 645 genes identified as differentially expressed (DE) between purebred and crossbred animals. Functional analysis showed differential regulation of pathways involved in energy and lipid metabolism, muscle development, and tissue disorders. In purebred animals, fetal body weight was associated with 35 DE genes involved in development, lipid metabolism and adipogenesis. In crossbred animals, fetal body weight was associated with 60 DE genes involved in muscle development, viability, and immunity. Interestingly, the results suggested an interaction genotype*weight for some DE genes. Fetal sex had only a modest effect on gene expression. This study allowed the identification of genes, metabolic pathways, biological functions and regulators related to fetal genotype, weight and sex, in animals sharing the same uterine environment. Our findings contribute to a better understanding of the molecular events that influence prenatal muscle development and highlight the complex interactions affecting transcriptional regulation during development.

Association of Glycated Proteins with Inflammatory Proteins and Periodontal Disease Parameters

Periodontitis is a chronic inflammatory condition that may contribute to diabetogenesis. The aim was to investigate the levels of glycated proteins and their correlation with periodontal and systemic inflammation. Fifty-one patients with periodontitis and 20 healthy subjects underwent probing pocket depth (PPD) measurements. PPD total and PPD disease with and without tooth adjustment were used as continuous indices. Marginal bone loss (MBL) for mandibular premolars and molars was measured digitally. Body mass index (BMI) and waist circumference (WC) were also analyzed. Glycated hemoglobin (HbA1c) and fructosamine (FrAm) levels were measured in all subjects. A multiplex proximity extension assay (PEA) was used to analyze the serum samples for simultaneous measurement of 92 proteins. Both HbA1c and FrAm inversely correlated with IL-10, FGF-21, MCP-1, and TNF beta amongst 16 proteins. HbA1c correlated directly with OPG. Parameters of disease severity were consistently significant for HbA1c. Adjusted PPD total and number of missing teeth were increased in diabetes whereas levels of RANKL and RANKL to OPG ratio were the highest in nondiabetic periodontitis patients. Hyperglycemic conditions in periodontitis patients are associated with reduced levels of anti-inflammatory proteins as well as dysregulated bone resorption.

Update on biomarkers of glycemic control

Attaining and maintaining good glycemic control is a cornerstone of diabetes care. The monitoring of glycemic control is currently based on the self-monitoring of blood glucose (SMBG) and laboratory testing for hemoglobin A1c (HbA1c), which is a surrogate biochemical marker of the average glycemia level over the previous 2-3 mo period. Although hyperglycemia is a key biochemical feature of diabetes, both the level of and exposure to high glucose, as well as glycemic variability, contribute to the pathogenesis of diabetic complications and follow different patterns in type 1 and type 2 diabetes. HbA1c provides a valuable, standardized and evidence-based parameter that is relevant for clinical decision making, but several biological and analytical confounders limit its accuracy in reflecting true glycemia. It has become apparent in recent years that other glycated proteins such as fructosamine, glycated albumin, and the nutritional monosaccharide 1,5-anhydroglucitol, as well as integrated measures from direct glucose testing by an SMBG/continuous glucose monitoring system, may provide valuable complementary data, particularly in circumstances when HbA1c results may be unreliable or are insufficient to assess the risk of adverse outcomes. Long-term associations of these alternative biomarkers of glycemia with the risk of complications need to be investigated in order to provide clinically relevant cut-off values and to validate their utility in diverse populations of diabetes patients.

Genome-Wide Association Study of Serum Fructosamine and Glycated Albumin in Adults Without Diagnosed Diabetes: Results From the Atherosclerosis Risk in Communities Study

Fructosamine and glycated albumin are potentially useful alternatives to hemoglobin A1c (HbA1c) as diabetes biomarkers. The genetic determinants of fructosamine and glycated albumin, however, are unknown. We performed genome-wide association studies of fructosamine and glycated albumin among 2,104 black and 7,647 white participants without diabetes in the Atherosclerosis Risk in Communities (ARIC) Study and replicated findings in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Among whites, rs34459162, a novel missense single nucleotide polymorphism (SNP) in RCN3, was associated with fructosamine (P = 5.3 × 10-9) and rs1260236, a known diabetes-related missense mutation in GCKR, was associated with percent glycated albumin (P = 5.9 × 10-9) and replicated in CARDIA. We also found two novel associations among blacks: an intergenic SNP, rs2438321, associated with fructosamine (P = 6.2 × 10-9), and an intronic variant in PRKCA, rs59443763, associated with percent glycated albumin (P = 4.1 × 10-9), but these results did not replicate. Few established fasting glucose or HbA1c SNPs were also associated with fructosamine or glycated albumin. Overall, we found genetic variants associated with the glycemic information captured by fructosamine and glycated albumin as well as with their nonglycemic component. This highlights the importance of examining the genetics of hyperglycemia biomarkers to understand the information they capture, including potential glucose-independent factors.

Calcium dobesilate: A drug treatment for diabetic retinopathy can negatively interfere with the measurement of glycated albumin using the enzymatic method

BACKGROUND

We reported that calcium dobesilate, a vasoprotective agent mainly used for diabetic retinopathy (DR), negatively interferes with glycated albumin (GA) assays involving enzymatic methods.

METHODS

A calcium dobesilate standard was added to 3serum pools in vitro to prepare concentration-response series according to Clinical and Laboratory Standards Institute EP7-A2 guidelines. Percentage deviation between each drug concentration and the drug-free sample was calculated for 6 commercially available GA assays. The acceptable limit of deviation for GA was ±5.61%. For in vivo analyses, changes in serum concentrations of GA and calcium dobesilate were monitored in eight healthy participants before and after oral calcium dobesilate administration.

RESULTS

At 16 μg/ml calcium dobesilate, within the therapeutic range, the percentage deviations for Asahi Kasei, Maccura, Leadman, Homa, and Medicalsystem assays were -8.7% to -49.7%, -2.0% to -47.7%, and -10.1% to -35.7% for low-, medium- and high-GA level interference pools, respectively, exhibiting dose-dependent negative interference. In vivo, calcium dobesilate ingestion was associated with statistically significant, falsely decreased measurements in 5 GA assays, 2 h after daily 500 mg administration.

CONCLUSIONS

Calcium dobesilate ingestion was associated with erroneously low measurements in 5 GA assays. The degree of interference varied greatly among the assays examined.

Maternal undernutrition and offspring sex determine birth-weight, postnatal development and meat characteristics in traditional swine breeds

Background

The aim of this study was to determine how maternal undernutrition during pregnancy and offspring birth-weight can affect the postnatal development of offspring under farm conditions, which may lead to consequences in its meat and carcass quality. The current study involved a total of 80 litters from Iberian sows fed a diet fulfilling daily requirements (n = 47; control) or providing 70% daily requirements (n = 33; underfed) from d 38 to d 90 of gestation when fetal tissue development begins. After birth, piglets born live were classified as low birth-weight (LBW; < 1 kg) and normal birth-weight (NBW; ≥1 kg). During the growing phase, 240 control and 230 underfed pigs (50% males and females) distributed by BW category and sex were studied until the slaughter.

Results

At birth and weaning, there were significant differences in all morphological measures and weight between NBW and LBW piglets as expected (P < 0.0005), but few effects of the gestational feed restriction. During the growing phase, NBW pigs continued with higher weight than LBW pigs on all the days of evaluation (P < 0.05), even though control-LBW-females and LBW-males showed a catch-up growth. However, underfed pigs showed slower growth and higher feed conversion ratio than control pigs (P < 0.0001) at 215 days old. Moreover, the average daily weight gain (ADWG) for the overall period was greater for NBW, male and control pigs than for their LBW, female and underfed pigs (P < 0.0001, P< 0.0005 and P< 0.05, respectively) and NBW pigs were slaughtered at a younger age than LBW pigs (P < 0.0001). After slaughtering, control pigs also had higher carcass yield and backfat depth than underfed pigs (P < 0.0005) and the maternal nutritional effect caused main changes in the polar lipid fraction of liver and loin. The fatty acid composition of loin in control pigs had higher C18:1n-9 and n-3 FA concentrations, as well as lower ∑n-6/∑n-3 ratio, than in underfed pigs (P < 0.005).

Conclusions

In brief, results showed that the effects of maternal nutritional restriction appeared and increased with offspring age, causing worse developmental patterns for underfed pigs than for control pigs.

Electronic supplementary material

The online version of this article (10.1186/s40104-018-0240-6) contains supplementary material, which is available to authorized users.

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

INTRODUCTION

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

Maillard reaction in food allergy: Pros and cons

Food allergens have a notable potential to induce various health concerns in susceptible individuals. The majority of allergenic foods are usually subjected to thermal processing prior to their consumption. However, during thermal processing and long storage of foods, Maillard reaction (MR) often takes place. The MR is a non-enzymatic glycation reaction between the carbonyl group of reducing sugars and compounds having free amino groups. MR may sometimes be beneficial by damaging epitope of allergens and reducing allergenic potential, while exacerbation in allergic reactions may also occur due to changes in the motifs of epitopes or neoallergen generation. Apart from these modulations, non-enzymatic glycation can also modify the food protein(s) with various type of advance glycation end products (AGEs) such as Nϵ-(carboxymethyl-)lysine (CML), pentosidine, pyrraline, and methylglyoxal-H1 derived from MR. These Maillard products may act as immunogen by inducing the activation and proliferation of various immune cells. Literature is available to understand pathogenesis of glycation in the context of various diseases but there is hardly any review that can provide a thorough insight on the impact of glycation in food allergy. Therefore, present review explores the pathogenesis with special reference to food allergy caused by non-enzymatic glycation as well as AGEs.

Glucose Variability Measures as Predictors of Oral Feeding Intolerance in Acute Pancreatitis: A Prospective Pilot Study

BACKGROUND

Oral feeding intolerance (OFI) is a common complication in patients with acute pancreatitis (AP). Variations in blood glucose are associated with impaired gastrointestinal function but, to date, measures of glucose variability have not been investigated to predict OFI in patients with AP.

AIM

To investigate the usefulness of several glucose variability measures in predicting the occurrence of OFI early in the course of AP.

METHODS

In this prospective cohort study, six measures of glucose variability were calculated prior to the occurrence of OFI. Multivariate binary logistic regression analyses were conducted, and the diagnostic performance and accuracy of glucose variability measures were assessed.

RESULTS

Of the 95 prospectively enrolled patients, 21 (22%) developed OFI. After adjusting for confounders, admission blood glucose concentration and mean blood glucose concentration were significantly associated with OFI [odds ratio 1.49 (95% confidence interval 1.01-2.20) and odds ratio 1.67 (95% confidence interval 1.07-2.61), respectively]. Both admission blood glucose and mean blood glucose had an area under the curve of 0.83 and positive likelihood ratios of 6.45 and 10.19, respectively. Blood glucose concentration before refeeding, standard deviation of blood glucose concentration, coefficient of variation, and mean amplitude of glycemic excursions were not significantly associated with OFI.

CONCLUSION

In-hospital blood glucose concentrations are associated with subsequent development of OFI in patients with AP. In particular, admission blood glucose and mean blood glucose could be useful predictors of OFI in this setting.

GLYCATED ALBUMIN AT 4 WEEKS CORRELATES WITH A1C LEVELS AT 12 WEEKS AND REFLECTS SHORT-TERM GLUCOSE FLUCTUATIONS

OBJECTIVE

Evaluate the performance of glycated albumin (GA) monitoring by comparing it to other measures of glycemic control during intensification of antidiabetic therapy.

METHODS

This 12-week, prospective, multicenter study compared the diagnostic clinical performance of GA to glycated hemoglobin A1C (A1C), fructosamine corrected for albumin (FRA), fasting plasma glucose (FPG), and mean blood glucose (MBG) estimated from self-monitoring of blood glucose (SMBG) and continuous glucose monitoring (CGM) in 30 patients with suboptimally controlled type 1 or 2 diabetes.

RESULTS

Mean A1C decreased from 9.5% to 8.1%. Mean SMBG correlated closely with CGM (Pearson r = 0.783 for daily estimates and r = 0.746 for weekly estimates, P<.0001). Both GA and FRA levels significantly correlated with changes from baseline in A1C and mean weekly SMBG (P<.001). The lowest observed median GA occurred at 4 weeks, followed by a small increase and then a slight reduction, mirroring changes in overall mean SMBG values. The median A1C fell throughout the treatment period, failing to reflect short-term changes in SMBG. A ≥1% reduction in GA at 4 weeks was significantly associated with a ≥0.5% change in A1C at 12 weeks (odds ratio [OR] = 19.0, 95% confidence interval [CI]: 1.4, 944, P = .018).

CONCLUSION

In patients receiving glucose-lowering therapy, changes in GA at 4 weeks were concordant with changes in A1C at 12 weeks, and both GA and FRA more accurately reflected short-term blood glucose fluctuations than A1C.

Salivary protein glycosylation as a noninvasive biomarker for assessment of glycemia

Assessment of short-term glycemic control can facilitate monitoring of diabetes development in at-risk individuals and monitoring response to lifestyle modification or medication. We evaluated salivary protein glycosylation levels as a novel, noninvasive, short-term glycemic index in comparison to hemoglobin A1c (HbA1c), fructosamine, 1,5-anhydroglucitol (1,5-AG), and continuous glucose monitoring (CGM). Ten subjects with type 2 diabetes were monitored by CGM and saliva and blood were collected at baseline and days 1, 7, 14, 21, and 28 for determination of salivary protein glycosylation, serum fructosamine, and serum 1,5-anhydroglucitol (1,5-AG) levels, as well as HbA1c (baseline and day 28). Weekly, 14-day, 21-day, and 28-day summary blood glucose measures from CGM were computed and matched to the time of each study visit. Salivary protein glycosylation exhibited a moderate correlation with fructosamine (r = .65) and 1,5-AG (r = -.48) at baseline, and weak correlation with HbA1c (r = .3). Salivary protein glycosylation exhibited a stronger correlation than fructosamine and 1,5-AG with 7-, 14-, and 21-day average BG (r = .84, .84, and .69, respectively, vs -.37, -.28, and .00 [fructosamine] and .00, -.21, and -.57 [1,5-AG]), maximum BG (r = .79, .76, and .53 vs -.09, -.21, and -.05 [fructosamine] and -.32, -.27, and -.52 [1,5-AG]), and percentage of time over 140 mg/dL (r = .87, .79, and .59 vs -.26, -.32, and .07 [fructosamine] and -.04, -.10, and -.50 [1,5-AG]). Salivary protein glycosylation represents a promising noninvasive technology for monitoring short-term glycemic control.

Fructosamine is a useful indicator of hyperglycaemia and glucose control in clinical and epidemiological studies--cross-sectional and longitudinal experience from the AMORIS cohort

CONTEXT

Fructosamine is a glycemic biomarker which may be useful for indication and control of diabetes respectively.

OBJECTIVE

The objective of the study was to evaluate fructosamine as an indicator of hyperglycaemia and glucose control in subjects with diabetes.

DESIGN, SETTING & PATIENTS

From the AMORIS cohort, subjects with serum glucose, fructosamine and HbA1c from the same examination were studied cross-sectionally and longitudinally (n = 10,987; 5,590 overnight-fasting). The guidelines of the American Diabetes Association were followed for classification of prediabetes and diabetes. Separate analyses were performed in patients with a newly detected or a known diagnosis of type 1 or type 2 diabetes respectively.

RESULTS

All three biomarkers were strongly correlated. With regard to the association between fructosamine and HbA1c Pearson linear correlation coefficients in the range of 0.67-0.75 were observed in fasting and non-fasting subjects with type 1 or type 2 diabetes. Analyses of glucose control in fasting patients with type 2 diabetes having all three biomarkers measured at three separate occasions within on average 290 days of the index examination showed similar trends over time for glucose, fructosamine and HbA1c. Discrimination of subjects with and without diabetes across the range of fructosamine levels was good (area under curve (AUC) 0.91-0.95) and a fructosamine level of 2.5 mmol/L classified subjects to diabetes with a sensitivity of 61% and a specificity of 97%.

CONCLUSIONS

Fructosamine is closely associated with HbA1c and glucose respectively and may be a useful biomarker of hyperglycaemia and glucose control in clinical and epidemiological studies.

[Significance of hemoglobin A1C in the management of diabetes in dialysis patients]

According to latest guidelines hemoglobin A1C plays a central role in the diagnosis of diabetes mellitus. It is well-known from epidemiologic studies that a high rate of diabetic patients enters into dialysis programs and these patients have an unfavourable mortality outcome. Based on surveys conducted in recent years in this patient group, hemoglobin A1C has an important role in assessing carbohydrate metabolism. However, there are several factors independent of blood glucose may affect hemoglobin A1C values both in hemodialysis and peritoneal dialysis patients. Hemodialysis disturbs hemoglobin A1c assessment because of an accelerated turnover of lost red blood cells. During peritoneal dialysis a considerable amount of glucose may be absorbed from the peritoneal solutions that may influence hemoglobin A1C level. Several alternative markers such as glycated albumin and fructosamine have been evaluated but they failed to have prognostic advantage. It has been concluded that among dialysis patients the hemoglobin A1C range between 6.5 and 8% is associated with the lowest mortality risk.

Comparative associations of diabetes risk factors with five measures of hyperglycemia

OBJECTIVE

To compare the associations of diabetes mellitus risk factors with nontraditional markers of hyperglycemia (glycated albumin, fructosamine, 1,5-anhydroglucitol (1,5-AG)) to those observed with traditional markers (fasting glucose, hemoglobin A1c (HbA1c)).

DESIGN

Cross-sectional study.

SETTING

The community-based Atherosclerosis Risk in Communities (ARIC) Study cohort.

PARTICIPANTS

A subsample of 1764 participants (309 with diagnosed diabetes and 1455 without diagnosed diabetes) from the ARIC Study who attended a clinic visit in 2005-2006.

MAIN OUTCOME MEASURES

Elevated levels of glycated albumin, fructosamine, 1,5-AG, fasting glucose, and HbA1c in persons with and without a diagnosis of diabetes.

RESULTS

The mean age of participants was 70 years (SD, 6), 43% were men, and 20% were African-American. Black race and family history of diabetes were generally positively associated with elevated levels of all biomarkers of hyperglycemia except 1,5-AG, which showed inverse but weaker associations with the risk factors examined. In general, patterns of risk factor associations observed for fasting glucose and HbA1c were similar to those observed for the nontraditional biomarkers of hyperglycemia but with one clear exception: body mass index (BMI). In persons without a diagnosis of diabetes, BMI was positively associated with fasting glucose and HbA1c, but the associations of BMI with glycated albumin and fructosamine were inverse, with high values of these markers at low levels of BMI. 1,5-AG, which is lowered in the setting of hyperglycemia, was positively associated with BMI.

CONCLUSIONS

Traditional diabetes risk factors have similar associations with glycated albumin and fructosamine as those for fasting glucose and HbA1c, with the exception of BMI. Risk factor associations with 1,5-AG were mostly inverse. The inverse associations of BMI with glycated albumin and fructosamine, and positive associations with 1,5-AG, may reflect pathways independent of glucose metabolism and merit further examination.

Fructosamine and glycated albumin for risk stratification and prediction of incident diabetes and microvascular complications: a prospective cohort analysis of the Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND

HbA1c is the standard measure by which to monitor long-term (2-3 months) glucose control in people with diabetes and is now used for diagnosis of diabetes. Fructosamine and glycated albumin are markers of short-term (2-4 weeks) glycaemic control that might add complementary prognostic information to HbA1c. Our aim was to clarify the performance of fructosamine and glycated albumin measurements for identifying people at risk of incident diabetes or diabetic complications.

METHODS

We measured glycated albumin and fructosamine in blood samples from 11 348 adults without diabetes and 958 adults diagnosed with diabetes mellitus (both type 1 and 2) who attended the second examination of the Atherosclerosis Risk in Communities (ARIC) study in 1990-92 (baseline). We assessed the associations of fructosamine and glycated albumin with risk of incident diabetes, retinopathy, and risk of incident chronic kidney disease (CKD), during two decades of follow-up. We compared these associations with those of HbA1c with incident diabetes, retinopathy, and CKD. For analyses of associations with incident diabetes and CKD, adjusted hazard ratios (HRs) and their corresponding 95% CIs were estimated using Cox proportional hazards models. Model discrimination was assessed using Harrell's C statistic.

FINDINGS

The HRs for incident diabetes were 4·96 (4·36-5·64) for fructosamine above the 95th percentile and 6·17 (5·45-6·99) for glycated albumin above the 95th percentile. Associations were attenuated but persisted after adjustment for HbA1c. Fructosamine and glycated albumin were strongly associated with retinopathy (p<0·0001 for trend). The multivariable-adjusted HRs for CKD for people with fructosamine and glycated albumin above the 95th percentile were 1·50 (95% CI 1·22-1·85) and 1·48 (1·20-1·83), respectively, when compared with people with no diabetes and fructosamine or glycated albumin below the 75th percentile. Prediction of incident CKD by fructosamine (C statistic 0·717) and glycated albumin (0·717) were nearly as strong as by HbA1c (0·726), but HbA1c outperformed fructosamine and glycated albumin for prediction of incident diabetes with C statistics of 0·760, 0·706, and 0·703, respectively.

INTERPRETATION

Fructosamine and glycated albumin were strongly associated with incident diabetes and its microvascular complications, with prognostic value comparable to HbA1c.

FUNDING

National Heart, Lung, and Blood Institute.

Review: Glycation of human serum albumin

Glycation involves the non-enzymatic addition of reducing sugars and/or their reactive degradation products to amine groups on proteins. This process is promoted by the presence of elevated blood glucose concentrations in diabetes and occurs with various proteins that include human serum albumin (HSA). This review examines work that has been conducted in the study and analysis of glycated HSA. The general structure and properties of HSA are discussed, along with the reactions that can lead to modification of this protein during glycation. The use of glycated HSA as a short-to-intermediate term marker for glycemic control in diabetes is examined, and approaches that have been utilized for measuring glycated HSA are summarized. Structural studies of glycated HSA are reviewed, as acquired for both in vivo and in vitro glycated HSA, along with data that have been obtained on the rate and thermodynamics of HSA glycation. In addition, this review considers various studies that have investigated the effects of glycation on the binding of HSA with drugs, fatty acids and other solutes and the potential clinical significance of these effects.