Does the measurement of serum fructosamine accurately reflect levels of glycated albumin in insulin-dependent diabetes?

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

Background

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

Materials and methods

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

Results

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

Conclusion

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

Prognostic implication of serum glycated albumin for patients with non-ST-segment elevation acute coronary syndrome undergoing percutaneous coronary intervention

BACKGROUND

It has been demonstrated that glycated albumin (GA) is significantly associated with diabetes complications and mortality. However, among patients diagnosed with non-ST-elevation acute coronary syndrome (NSTE-ACS) administered percutaneous coronary intervention (PCI), the predictive value of GA for poor prognosis is unclear.

METHODS

This study eventually included 2247 NSTE-ACS patients in Beijing Anzhen Hospital, Capital Medical University in January-December 2015 who received PCI. All patients were followed up until death or for 48 months post-discharge. The primary endpoint was major adverse cardio-cerebral events (MACCEs), including all-cause death, non-fatal myocardial infarction, ischemia-induced revascularization and non-fatal ischemic stroke.

RESULTS

In total, 547 (24.3%) MACCEs were recorded during the follow-up period. Upon adjusting for potential confounders, GA remained an important risk predictor of MACCEs (As nominal variate: hazard ratio [HR] 1.527, 95% confidence interval [CI] 1.236-1.886, P < 0.001; As continuous variate: HR 1.053, 95% CI 1.027-1.079, P < 0.001). GA addition significantly enhanced the predictive ability of the traditional risk model (Harrell's C-index, GA vs. Baseline model, 0.694 vs. 0.684, comparison P = 0.002; continuous net reclassification improvement (continuous-NRI) 0.085, P = 0.053; integrated discrimination improvement (IDI) 0.007, P = 0.020).

CONCLUSION

GA is highly correlated with poor prognosis in NSTE-ACS patients undergoing PCI, suggesting that it may be a major predictive factor of adverse events among these individuals.

Serum glycated albumin as good biomarker for predicting type 2 diabetes: A retrospective cohort study of China National Diabetes and Metabolic Disorders Survey

AIMS

Glycated albumin (GA) is a biomarker for short-term (2-3 weeks) glycaemic control. However, the predictive utility of GA for diabetes and prediabetes is largely uncharacterised. We aimed to investigate the relationships of baseline serum GA levels with incident diabetes and prediabetes.

METHODS

This was a longitudinal cohort study involving 516 subjects without diabetes or prediabetes at baseline. Blood glucose levels were observed during follow-up. Hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated using COX proportional hazard models. Receiver operating characteristic curves and areas under the curves (AUCs) were used to evaluate the discriminating abilities of glycaemic biomarkers and prediction models.

RESULTS

During a 9-year follow-up, 51 individuals (9.88%) developed diabetes and 92 (17.83%) prediabetes. Unadjusted HRs (95% CI) for both diabetes and prediabetes increased proportionally with increasing GA levels in a dose-response manner. Multivariable-adjusted HRs (95% CI) for diabetes were significantly elevated from 1.0 (reference) to 5.58 (1.86-16.74). However, the trend was no longer significant for prediabetes after multivariable adjustment. AUCs for GA, fasting blood glucose (FBG) and 2-h postprandial blood glucose (2h-PBG) for predicting diabetes were 0.698, 0.655 and 0.725, respectively. The AUCs for GA had no significant differences compared with those for FBG (p = 0.376) and 2h-PBG (p = 0.552). Replacing FBG or 2h-PBG or both with GA in diabetes prediction models made no significant changes to the AUCs of the models.

CONCLUSIONS

GA is of good prognostic utility in predicting diabetes. However, GA may not be a useful biomarker for predicting prediabetes.

Glycated albumin and the risk of chronic kidney disease in subjects with Type 2 Diabetes: A study in North Indian Population

AIM

Glycated albumin (GA) suggested being alternative glycemic marker than haemoglobin A1C (HbA1c) in patients with chronic kidney diseases (CKD). We investigated the association between GA and the progression of diabetic nephropathy (DN) in T2DM subjects.

METHODS

We recruited T2DM subjects with different stages of CKD who had regularly measured serum creatinine and estimated glomerular filtration rates (eGFR) according to Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines, HbA1c consecutively every 3 months along with GA levels and other anthropometric and demographic measurements. We grouped age and sex matched subjects into the CKD progression, Group I healthy subjects (n = 100, M: F;50:50). Group II T2DM subjects with eGFR ≥90 mL/min (n = 167, M:F; 76:91). Group III of T2DM patients with eGFR 60-89 mL/min (n = 91, M:F; 44:47). Group IV T2DM subjects with eGFR 30-59 mL/min (n = 68, M:F;31:37). Group V T2DM with eGFR ≤ 29 mL/min (n = 21, M:F; 13:8).

RESULTS

Pearson's correlation analysis between glycated albumin and biochemical parameters were established in all subjects. GA/HbA1c ratio increases with poor glycemic control except for nephrosis state.

CONCLUSION

Mean GA levels were more closely associated with DN progression than mean HbA1c in subjects with T2DM and can be implemented as an alternative diagnostic marker in nephropathy.

Glycated Serum Albumin and AGE Receptors

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

Evaluation of biological variation of glycated albumin (GA) and fructosamine in healthy subjects

BACKGROUND

Glycated albumin (GA) and fructosamine are nonenzymatically glycated proteins still frequently utilized for monitoring glycemic control in diabetics. To investigate the analytical variation and the degree of individuality of these glycemic markers, we have performed an experimental study under a well designed and standardized protocol.

METHODS

We collected five specimens from each of 18 apparently healthy subjects (9 men and 9 women, ages 26-52 years), on the same day, every two weeks for two months. Samples were stored at -80°C until analysis and assayed in duplicate in a single analytical run. GA and fructosamine were measured using enzymatic (Lucica®GA-L, Asahi Kasei Pharma, AKP, Tokyo, Japan) and colorimetric assays, respectively, on a Modular P Roche system (Roche Diagnostics GmbH, Mannheim, Germany). Data were analyzed by ANOVA.

RESULTS

Analytical coefficient of variation (CVA) was 1.7%, 2.3% and 2.8% for GA, albumin and fructosamine, respectively. Within-subject (CVW) and between-subject (CVG) coefficients of variation were 2.1% and 10.6% for GA, 2.3% and 2.9% for albumin, and 2.3% and 6.3% for fructosamine. The estimated critical difference (CD) was 7.5% for GA, 9% for albumin and 10% for fructosamine.

CONCLUSIONS

The good quality achieved by the analytical method for GA assessment and the reduced within-subject biological variation would allow to recommend this test in clinical practice for evaluation of glycemic control along with measurement of glycated hemoglobin.

Fructosamine as a screening-test for gestational diabetes mellitus: a reappraisal

Fructosamine, glycosylated hemoglobin (HbA1c) and serum total proteins were measured in normal nondiabetic pregnant women (n = 170) at three stages of pregnancy (14-18, 24-28, and 32-40 weeks of gestation). No significant correlation was found between fructosamine and either HbA1c or total plasma proteins. Only early in pregnancy (less than 20 weeks of gestation) was a correlation found between fructosamine and fasting blood glucose (r = 0.40, P less than 0.05). There was also no correlation between either tests (i.e. fructosamine and HbA1c) and fetal birthweight. The value of fructosamine measurement in the detection of diabetes in pregnancy was further tested in a group of high-risk patients (n = 98) for developing carbohydrate intolerance. It is concluded that fructosamine has limited value as a screening test for gestational diabetes mellitus, particularly for the mild form of the glucose intolerance.

Maternal serum fructosamine and maternofetal glucose and insulin homeostasis in normal pregnancy

Well-defined normal values are necessary to identify pregnancies complicated by gestational diabetes (GD) and thus further reduce perinatal morbidity and mortality from this condition. The present study defined the range for the oral glucose tolerance test (oGTT) in 2578 pregnancies. After exclusion of abnormal results 822 randomized patients were used to define normal values for fructosamine, HbA1c, insulin, glucose and C-peptide in the maternal serum; insulin, glucose and fructosamine in the amniotic fluid; and insulin, glucose, C-peptide and fructosamine in the cord blood.

A comparison of direct measures of glycaemia and glycated blood proteins in insulin-dependent diabetes mellitus

We have studied associations between various direct measures of glycaemia and glycated blood proteins in 113 subjects with insulin-dependent diabetes mellitus (IDDM), and examined whether or not the 'fructosamine' assay results were affected by differing patient serum concentrations of lipids, albumin or C peptide. Serum fructosamine correlated less closely with HbA1 (r = 0.44) than did HbA1 with glycated serum albumin (GSA) (r = 0.68). Serum fructosamine and GSA also were poorly correlated (r = 0.48). Although fructosamine, HbA1 and GSA correlated to a similar degree with fasting blood glucose (r range 0.34 to 0.37), GSA was most closely related to mean blood glucose (r = 0.39 vs. 0.30-0.35) and the M value (a marker of diurnal glycaemic instability) (r = 0.42 vs. 0.33-0.35). The serum concentration of fructosamine was not significantly affected by a variation in serum cholesterol, but tended to be lower in subjects with moderate hypertriglyceridaemia (p = 0.05). The fructosamine assay may be altered by moderately lipaemic serum but is not affected by serum albumin concentration in normoalbuminaemic patients with IDDM. Our study indicates, however, that GSA is a more reliable marker of short-term glycaemic control in IDDM than fructosamine.

An analysis of glycosylated blood proteins and blood glucose profiles over one year in patients with type 1 diabetes

The clinical value of prospective measurement of several direct and indirect measures of blood glucose control in the management of Type 1 diabetes has been investigated. Ninety-eight Type 1 diabetic patients were followed over a period of 1 year after a 6-week period of intensification of management, with monthly measurements of blood glucose profiles and 3-monthly HbA1, glycosylated serum albumin, and fructosamine measurements. All measures improved markedly after the initial 6-week period (p less than 0.001), and all except glycosylated serum albumin and fructosamine then remained relatively stable. Of fourteen serial comparisons, glycosylated blood proteins were significantly correlated more often with levels of mean blood glucose and M value (on 4-7 occasions, rs 0.30-0.58) than with fasting blood glucose levels (on only 2-3 occasions, rs 0.34-0.44). Serum fructosamine levels correlated significantly with mean blood glucose on four occasion (rs 0.30-0.50), whilst glycosylated serum albumin and HbA1 correlated with mean blood glucose on six occasions (rs 0.36-0.54). Glycosylated serum albumin correlated with HbA1 and fructosamine levels throughout the year (rs 0.47-0.68 and 0.48-0.76, respectively), but HbA1 and fructosamine were less clearly correlated with each other (rs 0.38-0.44), with no significant association immediately after the period of intensive management or 3 months later.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of plasma glycoalbumin levels with a monoclonal antibody based ELISA

We have reported the establishment of hybridomas secreting monoclonal antibody that specifically recognizes glycated albumin. The antibody, raised in mice immunized with nonenzymatically glycated albumin isolated from human plasma, recognizes glycated epitopes residing in albumin but not in other plasma proteins, and does not react with unglycated albumin. We now report utilization of this antibody to measure the amount of nonenzymatically glycated albumin in human plasma. When immobilized onto microtiter wells in ELISA format, A717 yields a linear dose-response relationship upon incubation with authentic purified glycoalbumin. This allows construction of standard curves from which the amount of circulating glycoalbumin can be determined. The glycoalbumin level (mean +/- SEM) in 12 samples from nondiabetic subjects was 2.4 +/- 0.22% of total albumin. In normal plasma spiked with known amounts of purified glycoalbumin, values measured with this assay were close to 100% of expected values. Glycoalbumin levels in samples from 25 diabetic subjects ranged from 1.6 to 11.6%, with a mean +/- SEM of 4.5 +/- 1.2%. Glycoalbumin levels in diabetic samples correlated significantly (r = 0.93) with glycohemoglobin values. The ability of this assay to quantitate glycoalbumin, an index of the prevailing blood glucose concentrations over the preceding 2-3 weeks, makes it a favourable candidate for utilization in the clinical setting to monitor glycemic control in diabetic subjects.

Screening for diabetes: does measurement of serum fructosamine help?

The diagnostic sensitivity and specificity for diabetes of serum fructosamine levels and fasting venous blood glucose concentrations were compared in 613 subjects during a diabetes community screening programme of 1049 adult Muslim Asians in Dar es Salaam, Tanzania. Using WHO (1985) criteria 228 had impaired glucose tolerance (IGT), 41 had previously been diagnosed as having diabetes while 32 had newly recognized diabetes. The mean (+/- SD) serum fructosamine levels were 20.9 +/- 3.2, 21.6 +/- 3.2, 23.9 +/- 4.9, and 30.1 +/- 7.9 (mumol g-1 albumin) in subjects with normal glucose tolerance, IGT, newly diagnosed diabetes, and previously diagnosed diabetes, respectively (p less than 0.001 for differences between groups). The specificity of values above the mean +2SD normal was 99% for abnormal glucose tolerance with a sensitivity of only 22% for diabetes. The predictive values were 44% and 97% for positive and negative results, respectively. Very little difference from normal was found for IGT subjects. Expressing fructosamine values in absolute terms or per gram albumin made little difference to sensitivity and specificity. The sensitivity was only 32% for fasting blood glucose greater than or equal to 6.7 mmol l-1, 73% for values greater than or equal to 5.5 mmol l-1, and 100% for fasting blood glucose greater than or equal to 4.5 mmol l-1. It is concluded that both serum fructosamine and fasting blood glucose are poor screening and diagnostic tests for diabetes and for IGT, and that glucose loading is required.

Serum fructosamine does reflect levels of glycated serum albumin in insulin-dependent diabetics

Fructosamine was measured in the serum of 62 patients with insulin-dependent diabetes (IDD) and 32 non-diabetics and the results compared with glycated albumin levels (GSA) measured using the affinity medium Cibarcron blue F3GA. Good correlations were found both for the IDD patients (r = 0.93) and the combined group of IDD plus non-diabetics (r = 0.95). We conclude, that fructosamine measurements accurately reflect GSA concentrations, and, therefore, provide a practical method for assessing intermediate term glycaemia in IDD.

Comparison of fructosamine and glycated haemoglobin in children with type 1 (insulin-dependent) diabetes mellitus

In six children (age: mean 8.4 years, range 2.2-12.6 years) with newly diagnosed Type 1 (insulin-dependent) diabetes mellitus, plasma fructosamine and glycated haemoglobin (HbA1) were compared in respect to their disappearance during the first month after diagnosis during well controlled glycaemia. The disappearance of the surplus plasma fructosamine and HbA1 was calculated applying exponential equations. The estimated half-lives of fructosamine (mean 57.2 days, range 40.7-77 days) and HbA1 (mean 59.7 days, range 43.3-82 days) were not significantly different, a finding which is left unexplained.

Plasma fructosamine in non-diabetic pregnancy

Plasma fructosamine and its relation to plasma total protein and albumin was examined in 40 non-diabetic pregnant women. Plasma fructosamine did not correlate with haemoglobin A1 or plasma albumin. The mean intra-individual ranges were plasma fructosamine 0.53 mmol/l (SD 0.17); haemoglobin A1 1.42% (SD 0.42); plasma fructosamine/g albumin 0.024 mmol (SD 0.005) and plasma fructosamine/g total protein 0.008 mmol (SD 0.003). A high degree of individuality for these variables was also observed.