1-Amino-1-deoxy-d-fructose ("fructosamine") and its derivatives: An update

1-Amino-1-deoxy-d-fructose (fructosamine, FN) derivatives are omnipresent in all living organisms, as a result of non-enzymatic condensation and Amadori rearrangement reactions between free glucose and biogenic amines such as amino acids, polypeptides, or aminophospholipids. Over decades, steady interest in fructosamine was largely sustained by its role as a key intermediate structure in the Maillard reaction that is responsible for the organoleptic and nutritional value of thermally processed foods, and for pathophysiological effects of hyperglycemia in diabetes. New trends in fructosamine research include the discovery and engineering of FN-processing enzymes, development of advanced tools for hyperglycemia monitoring, and evaluation of the therapeutic potential of both fructosamines and FN-recognizing proteins. This article covers developments in the field of fructosamine and its derivatives since 2010 and attempts to ascertain challenges in future research.

1-Amino-1-deoxy-d-fructose ("fructosamine") and its derivatives

Fructosamine has long been considered as a key intermediate of the Maillard reaction, which to a large extent is responsible for specific aroma, taste, and color formation in thermally processed or dehydrated foods. Since the 1980s, however, as a product of the Amadori rearrangement reaction between glucose and biologically significant amines such as proteins, fructosamine has experienced a boom in biomedical research, mainly due to its relevance to pathologies in diabetes and aging. In this chapter, we assess the scope of the knowledge on and applications of fructosamine-related molecules in chemistry, food, and health sciences, as reflected mostly in publications within the past decade. Methods of fructosamine synthesis and analysis, its chemical, and biological properties, and degradation reactions, together with fructosamine-modifying and -recognizing proteins are surveyed.

Fructosamine as a predictor of incident diabetic microvascular disease in a population with high prevalence of red cell disorders: A cohort study

AIMS

Fructosamine can be used to estimate glycaemia in individuals in whom HbA1c may be unreliable. We aimed to establish clinically useful fructosamine treatment targets in a population with a high prevalence of conditions affecting erythrocyte survival, including variant haemoglobin and G6PD deficiency.

METHODS

Fructosamine was measured on a clinical basis in individuals in whom HbA1c was suspected to be unreliable by their primary physician. Study endpoints were incident retinopathy and albuminuria in individuals with Prediabetes (n = 60), Type 1 (n = 161) or Type 2 diabetes (n = 1350) during follow up of 4.4 ± 2.3 years.

RESULTS

Fructosamine ≥ 250 umol/L was significantly associated with incident retinopathy, and fructosamine ≥ 300 umol/L with incident microalbuminuria, in univariate analysis and adjusted for established risk factors. Fructosamine ≥ 250 umol/L was also significantly associated with incident retinopathy in individuals with HbA1c < 7.0% (53 mmol/mol) at inclusion.

CONCLUSIONS

In this patient population, a single measurement of fructosamine significantly and independently predicts incident retinopathy in individuals with HbA1c < 7.0% (53 mmol/mol). Routine measurement of fructosamine on at least one occasion is recommended as part of assessment of prediabetes or diabetes mellitus in populations with a high prevalence of conditions affecting erythrocyte lifespan.

Fructosamine and glycated hemoglobin as biomarkers of glycemic control in people with type 2 diabetes mellitus and cancer (GlicoOnco study)

INTRODUCTION

Glycemic control is important to avoid diabetes complications in individuals with cancer. There is no evidence for HbA1c and fructosamine as reliable biomarkers in these conditions. There are particularities in caring for patients with diabetes and cancer that can alter these biomarkers.

OBJECTIVE

The aim of this study was to evaluate HbA1c and fructosamine as glycemic biomarkers in people with type 2 diabetes and cancer, undergoing clinical or surgical oncological treatment.

METHODS

The authors conducted a single-center, retrospective analysis with people who have cancer and diabetes. Comparison of glycemic biomarkers (HbA1c, fructosamine, and Self-Monitoring of Blood Glucose [SMBG]) was performed including evaluation in individuals undergoing chemotherapy, using glucocorticoids, with anemia, hypoproteinemia or with reduced estimated Glomerular Filtration Rate (eGFR).

RESULTS

There was a strong positive correlation between fructosamine and HbA1c (n = 318, r = 0.66, p < 0.001) in people with diabetes and cancer even in those under chemotherapy (n = 101, r = 0.61, p < 0.001) or using glucocorticoids (n = 96, r = 0.67, p<0.001). There was a strong correlation between HbA1c and fructosamine in subjects with anemia (n = 111, r = 0.66, p < 0.001), hypoproteinemia (n = 54, r = 0.67, p < 0.001), or with eGFR ≥ 60 mL/min/1.73 m2 (n = 189, r = 0.70, p < 0.001), and moderate correlation with hypoalbuminemia (n = 21, r = 0.54, p = 0.001) and with reduced eGFR (n = 67, r = 0.57, p < 0.001). The correlations between fructosamine and HbA1c with SMBG were moderate (n = 164, r = 0.49, p < 0.001; n = 111, r = 0.55, p < 0.001, respectively), strong in subjects undergoing chemotherapy, with hypoalbuminemia or hypoproteinemia, and at least moderate, if eGFR < 60 mL/min/1.73 m2 or with anemia.

CONCLUSIONS

Fructosamine and HbA1c can be used as glycemic biomarkers in people with diabetes and cancer, even in those with anemia, hypoproteinemia, or undergoing chemotherapy.

Diagnostic performance of glycated haemoglobin (HbA1c) for diabetes mellitus in dogs

The objective of this study was to determine the diagnostic performance of glycated haemoglobin (HbA1c) for canine diabetes mellitus (DM) and compare it with that of serum fructosamine. Aliquots of blood samples collected for diagnostic purposes from adult dogs were used. HbA1c was measured using a previously validated capillary electrophoresis assay. The dogs were allocated into four groups: (1) DM; (2) hyperadrenocorticism (HAC); (3) long-term corticosteroid therapy (CST); and (4) various chronic diseases (VD). In total, 88 dogs were included as follows: DM (n = 11), HAC (n = 10), CST (n = 14), and VD (n = 53). Fructosamine was measured in all four groups as follows: DM (n = 6), HAC (n = 7), CST (n = 9), and VD (n = 42). Median (range) serum glucose concentration was higher (P < 0.001) in the DM group (22.8 mmol/L; range, 15.6-29.3 mmol/L) compared to HAC (5.9 mmol/L; range, 4.2-6.8 mmol/L), CST (5.6 mmol/L; range, 4.3-23.3 mmol/L), and VD (5.5 mmol/L; range, 4.1-9.4 mmol/L) groups. Mean (± standard deviation) HbA1c was higher (P < 0.001) in the DM group (6.3% ± 1.5%) compared to HAC (1.9% ± 0.5%), CST (1.7% ± 0.5%), and VD (1.9% ± 0.5%) groups. All diabetic dogs and none of the other dogs had HbA1c levels above the cut-off value for DM (3.3%), indicating an accuracy of 100% in diagnosing DM. Significant differences (P < 0.01) were observed in median fructosamine between the DM group (389 μmol/L; range, 348-865 μmol/L) and the HAC (306 μmol/L; range, 167-348 μmol/L) and the VD (316 μmol/L; range, 189-500 μmol/L) groups. Fructosamine had an accuracy of 84.4% for the diagnosis of DM. When used for the diagnosis of canine DM, HbA1c measured with this specific assay had excellent diagnostic accuracy and was superior to serum fructosamine.

Estimated average blood glucose level based on fructosamine level

Objective

To define the mathematical relationship between fructosamine levels and average glucose values.

Subjects and methods

The study comprised laboratory data of 1,227 patients with type 1 or 2 diabetes mellitus. Fructosamine levels measured at the end of a 3-week period were compared against the average blood glucose levels of the previous 3 weeks. Average glucose levels were determined by the weighted average of the daily fasting capillary glucose results performed during the study period, and the plasma glucose measured in the same sample collected for fructosamine measurement.

Results

In total, 9,450 glucose measurements were performed. Linear regression analysis between fructosamine levels and average glucose levels showed that for each 1.0 μmol/L increase in fructosamine level there was a 0.5 mg/dL increase in average glucose level, as estimated by the equation Mean glucose level = (0.5157 × Fructosamine) - 20. The coefficient of determination (r2 = 0.353492, p < 0.006881) allowed the calculation of the estimated average glucose based on fructosamine level.

Conclusion

Our study demonstrated a linear correlation between fructosamine level and mean blood glucose level, suggesting that fructosamine levels can be a proxy for the average glucose level in assessing the metabolic control of patients with diabetes.

Proteomics profiles of blood glucose-related proteins involved in a Chinese longevity cohort

BACKGROUND

High blood glucose level is one of the main characteristics of diabetes mellitus. Based on previous studies, it is speculated longevity families may have certain advantages in blood glucose regulation. However, limited information on these items has been reported. The purpose of this study was to profile differences of plasma proteomics between longevity subjects (with normal fructosamine (FUN) level) and non-longevity area participants (with exceeding standard FUN level).

METHODS

In this study, a TMT-based proteomics analysis was used to profile differences of plasma proteomics between longevity subjects (with normal FUN level) and non-longevity area participants (with exceeding standard FUN level). Results were validated by Luminex detection.

RESULTS

A total of 155 differentially expressed proteins (DEPs) were identified between these two groups. The DEPs related to blood glucose regulation were mainly involved in glycolysis/gluconeogenesis, pyruvate metabolism and propanoate metabolism, and most of the DEPs were contained in carbohydrate metabolism, PI3K-Akt pathway, glucagon signaling pathway and inflammatory response. Validation by Luminex detection confirmed that CD163 was down-regulated, and SPARC, PARK 7 and IGFBP-1 were up-regulated in longevity participants.

CONCLUSIONS

This study not only highlighted carbohydrate metabolism, PI3K-Akt pathway, glucagon signaling pathway and inflammatory response may play important roles in blood glucose regulation, but also indicated that YWHAZ, YWHAB, YWHAG, YWHAE, CALM3, CRP, SAA2, PARK 7, IGFBP1 and VNN1 may serve as potential biomarkers for predicting abnormal blood glucose levels.

Metabolic changes associated with two endocrine abnormalities in dogs: elevated fructosamine and low thyroxine

INTRODUCTION

Metabolomics studies in canine endocrine abnormalities are sparse and basic information on these abnormalities must be generated.

OBJECTIVES

To characterize the metabolic changes associated with elevated fructosamine, reflecting poor glycemic control, and low thyroxine, a thyroid hormone controlling metabolism.

METHODS

Leftovers of clinical serum samples; 25 controls, 79 high fructosamine, and 47 low thyroxine, were analyzed using ¹H NMR and differences were evaluated using Firth logistic regression.

RESULTS

Both high fructosamine and low thyroxine were associated with changes in concentrations of multiple metabolites, including glycoprotein acetyls and lipids.

CONCLUSION

These findings suggest promising makers for further research and clinical validation.

Elevated levels of fructosamine are independently associated with SARS-CoV-2 reinfection: A 12-mo follow-up study

BACKGROUND

The association between blood levels of fructosamine (FMN) and recurrent coronavirus disease 2019 (COVID-19) is currently unclear.

AIM

To investigate a prospective relationship between blood levels of FMN and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfection.

METHODS

A total of 146 Chinese hospitalized patients infected with SARS-CoV-2 were consecutively collectively recruited and followed from January 2020 to May 2021. Diagnosis of COVID-19 and SARS-CoV-2 reinfection was based on the diagnostic criteria and treatment protocol in China. The levels of FMN were determined in blood and divided into tertiles based on their distribution in the cohort of COVID-19 patients. Multivariate-adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated for SARS-CoV-2 reinfection across the tertiles of FMN levels. A Cox regression model was used to generate the HR for SARS-CoV-2 reinfection in the participants in the top tertile of FMN levels compared with those at the bottom. Disease-free survival was used as the time variable, and relapse was used as the state variable, adjusted for age, gender, influencing factors such as diabetes mellitus, hypertension, and corticosteroid therapy, and clinical indexes such as acute liver failure, acute kidney failure, white blood cell (WBC) count, C-reactive protein, prognostic nutritional index (PNI), and blood lipids. Kaplan-Meier analysis with log-rank tests was used to compare the survival rate between patients with elevated FMN levels (FMN > 1.93 mmol/L, the top tertile) and those with nonelevated levels.

RESULTS

Clinical data for the 146 patients with confirmed COVID-19 [age 49 (39-55) years; 49% males] were analyzed. Eleven patients had SARS-CoV-2 reinfection. The SARS-CoV-2 reinfection rate in patients with elevated FMN levels was significantly higher than that in patients with nonelevated FMN (17% vs 3%; P = 0.008) at the end of the 12-mo follow-up. After adjustments for gender, age, diabetes mellitus, hypertension, corticosteroid therapy, WBC count, PNI, indexes of liver and renal function, and blood lipids, patients with nonelevated FMN levels had a lower risk of SARS-CoV-2 reinfection than those with elevated FMN levels (HR = 6.249, 95%CI: 1.377-28.351; P = 0.018). Kaplan-Meier analysis showed that the cumulative survival rate of patients infected with SARS-CoV-2 was higher in patients with nonelevated FMN levels than in those with elevated FMN levels (97% vs 83%; log rank P = 0.002).

CONCLUSION

Elevated levels of FMN are independently associated with SARS-CoV-2 reinfection, which highlights that patients with elevated FMN should be cautiously monitored after hospital discharge.

Assessment of glycemia in chronic kidney disease

Reliable assessment of glycemia is central to the management of diabetes. The kidneys play a vital role in maintaining glucose homeostasis through glucose filtration, reabsorption, consumption, and generation. This review article highlights the role of the kidneys in glucose metabolism and discusses the benefits, pitfalls, and evidence behind the glycemic markers in patients with chronic kidney disease. We specifically highlight the role of continuous glucose monitoring as an emerging minimally invasive technique for glycemic assessment.

Glycemic control is not related to cerebral small vessel disease in neurologically asymptomatic individuals with type 1 diabetes

AIMS

To determine if medium- and long-term blood glucose control as well as glycemic variability, which are known to be strong predictors of vascular complications, are associated with underlying cerebral small vessel disease (cSVD) in neurologically asymptomatic individuals with type 1 diabetes.

METHODS

A total of 189 individuals (47.1% men; median age 40.0, IQR 33.0-45.2 years) with type 1 diabetes (median diabetes duration of 21.7, IQR 18.3-30.7 years) were enrolled in a cross-sectional retrospective study, as part of the Finnish Diabetic Nephropathy (FinnDiane) Study. Glycated hemoglobin (HbA_1c) values were collected over the course of ten years before the visit including a clinical examination, biochemical sampling, and brain magnetic resonance imaging. Markers of glycemic control, measured during the visit, included HbA_1c, fructosamine, and glycated albumin.

RESULTS

Signs of cSVD were present in 66 (34.9%) individuals. Medium- and long-term glucose control and glycemic variability did not differ in individuals with signs of cSVD compared to those without. Further, no difference in any of the blood glucose variables and cSVD stratified for cerebral microbleeds (CMBs) or white matter hyperintensities were detected. Neither were numbers of CMBs associated with the studied glucose variables. Additionally, after dividing the studied variables into quartiles, no association with cSVD was observed.

CONCLUSIONS

We observed no association between glycemic control and cSVD in neurologically asymptomatic individuals with type 1 diabetes. This finding was unexpected considering the large number of signs of cerebrovascular pathology in these people after two decades of chronic hyperglycemia and warrants further studies searching for underlying factors of cSVD.

Hemoglobin A1c and Fructosamine Evaluated in Patients with Type 2 Diabetes Receiving Peritoneal Dialysis Using Long-Term Continuous Glucose Monitoring

INTRODUCTION

Shortened erythrocyte life span and erythropoietin-stimulating agents may affect hemoglobin A1c (HbA1c) levels in patients receiving peritoneal dialysis (PD). We compared HbA1c with interstitial glucose measured by continuous glucose monitoring (CGM) in patients with type 2 diabetes receiving PD.

METHODS

Fourteen days of CGM (Ipro2, Medtronic) were performed in 23 patients with type 2 diabetes receiving PD and in 23 controls with type 2 diabetes and an estimated glomerular filtration rate over 60 mL/min/1.73 m2. Patients were matched on gender and age (±5 years). HbA1c (mmol/mol), its derived estimate of mean plasma glucose (eMPGA1c) (mmol/L), and fructosamine (µmol/L) were measured at the end of the CGM period and compared with the mean sensor glucose (mmol/L) from CGM.

RESULTS

In the PD group, mean sensor glucose was 0.98 (95% con-fidence interval (CI): 0.43-1.54) mmol/L higher than the eMPGA1c compared with the control group (p = 0.002) where glucose levels were nearly identical (-0.05 (95% CI: -0.35-0.25) mmol/L). A significant association was found between fructosamine and mean sensor glucose using linear regression with no difference between slopes (p = 0.89) or y-intercepts (p = 0.28).

DISCUSSION/CONCLUSION

HbA1c underestimates mean plasma glucose levels in patients with type 2 diabetes receiving PD. However, the clinical significance of this finding is undetermined. Fructosamine seems to more accurately reflect glycemic status. CGM or fructosamine could complement HbA1c to increase the accuracy of glycemic monitoring in the PD population.

Glycated albumin as biomarker: Evidence and its outcomes

Glycemic control markers are important for the diagnosis and treatment of diabetes. Hemoglobin A1c (A1C) is an important marker that is mandatory in routine medical examinations; however, it is well known that it has some limitations. In this review, we focus on the limitation of A1C and introduce a relatively new marker, glycated albumin (GA), which can be used to complement A1C. First, for a better understanding of the characteristics of each marker, we sort the similarities and differences of glycemic control markers as well as the characteristics of each marker. Second, we point out the limitation of A1C, introduce GA as an alternative indicator, and discuss the limitations of GA. Finally, we summarize important evidence regarding the utility of GA. We hope that this review provides useful information that permits more effective usage of GA as well as other glycemic control markers.

The Accuracy of Hemoglobin A1c and Fructosamine Evaluated by Long-Term Continuous Glucose Monitoring in Patients with Type 2 Diabetes Undergoing Hemodialysis

INTRODUCTION

The accuracy of hemoglobin A1c (HbA1c) as a glycemic marker in patients with type 2 diabetes (T2D) receiving hemodialysis (HD) remains unknown. To assess accuracy, we compared HbA1c and fructosamine levels with interstitial glucose measured by continuous glucose monitoring (CGM) in patients with T2D receiving HD.

METHODS

Thirty patients in the HD group and 36 patients in the control group (T2D and an estimated glomerular filtration rate >60 mL/min/1.73 m2) completed the study period of 17 weeks. CGM (Ipro2®, Medtronic) was performed 5 times for periods of up to 7 days (with 4-week intervals) during a 16-week period. HbA1c (mmol/mol), the estimated mean plasma glucose from HbA1c (eMPGA1c [mmol/L]) and fructosamine (μmol/L) was measured at week 17 and compared with mean sensor glucose levels from CGM.

FINDINGS

In the HD group, mean sensor glucose was 1.4 mmol/L (95% confidence interval [CI]: 1.0-1.8) higher than the eMPGA1c, whereas the difference for controls was 0.1 mmol/L (95% CI: -0.1-[0.4]; p < 0.001). Adjusted for mean sensor glucose, HbA1c was lower in the HD group (-7.3 mmol/mol, 95% CI: -10.0-[-4.7]) than in the control group (p < 0.001), with no difference detected for fructosamine (p = 0.64).

DISCUSSION

HbA1c evaluated by CGM underestimates plasma glucose levels in patients receiving HD. The underestimation represents a clinical challenge in optimizing glycemic control in the HD population. Fructosamine is unaffected by the factors affecting HbA1c and appears to be more accurate for glycemic monitoring. CGM or fructosamine could thus complement HbA1c in obtaining more accurate glycemic control in this patient group.

Use of large scale EHR data to evaluate A1c utilization among sickle cell disease patients

BACKGROUND

The glycated hemoglobin (A1c) test is not recommended for sickle cell disease (SCD) patients. We examine ordering patterns of diabetes-related tests for SCD patients to explore misutilization of tests among this underserved population.

METHODS

We used de-identified electronic health record (EHR) data in the Cerner Health Facts™ (HF) data warehouse to evaluate the frequency of A1c and fructosamine tests during 2010 to 2016, for 37,151 SCD patients from 393 healthcare facilities across the United States. After excluding facilities with no A1c data, we defined three groups of facilities based on the prevalence of SCD patients with A1c test(s): adherent facilities (no SCD patients with A1c test(s)), minor non-adherent facilities, major non-adherent facilities.

RESULTS

We determined that 11% of SCD patients (3927 patients) treated at 393 facilities in the US received orders for at least one A1c test. Of the 3927 SCD patients with an A1c test, only 89 patients (2.3%) received an order for a fructosamine test. At the minor non-adherent facilities, 5% of the SCD patients received an A1c test while 58% of the SCD patients at the least adherent facilities had at least one A1c test. Overall, the percent of A1c tests ordered for SCD patients between 2010 and 2016 remained similar.

CONCLUSIONS

Inappropriate A1c test orders among a sickle cell population is a significant quality gap. Interventions to advance adoption of professional recommendations that advocate for alternate tests, such as fructosamine, can guide clinicians in test selection to reduce this quality gap are discussed. The informatics strategy used in this work can inform other largescale analyses of lab test utilization using de-identified EHR data.

Impact of triglycerides and waist circumference on insulin resistance and β-cell function in non-diabetic first-degree relatives of type 2 diabetes

BACKGROUND

Although there is abundant evidence indicating the relative contribution of insulin resistance (HOMA-IR) and β-cell dysfunction (HOMA-β) among first-degree relatives (FDRs) of Type 2 DM patients, few studies reported the association between HOMA-IR and HOMA-β with metabolic syndrome. Our objective was to evaluate the impact of metabolic syndrome factors on HOMA-IR, HOMA-β and glycoproteins in non-diabetic FDRs.

METHODS

In this study, 103 Yemeni male subjects aged 25-42 years, with BMI < 25 kg/m² were examined, 39 of whom were normal subjects with no family history of diabetes served as control and 64 subjects were non-diabetic FDRs of Type 2 DM patients.

RESULTS

Both glycoproteins, glycated haemoglobin (HbA1c) and fructosamine as well as insulin, HOMA-IR and HOMA-β were significantly (p = 4.9 × 10^-9; 6.0 × 10^-8; 6.6 × 10^-12; 1.3 × 10^-7; 5.5 × 10^-12, respectively) higher in non-diabetic FDRs as compared to control group. Fasting plasma glucose, though within normal range, were significantly (p = 0.026) higher in non-diabetic FDRs. Linear regression analysis showed that both TG and WC are the main metabolic syndrome factors that significantly increased HOMA-IR (B = 0.334, p = 1.97 × 10^-6; B = 0.024, p = 1.05 × 10^-5), HOMA-β (B = 16.8, p = 6.8 × 10^-5; B = 0.95, p = 0.004), insulin (B = 16.5, p = 1.2 × 10^-6; B = 1.19, p = 8.3 × 10^-6) and HbA1c (B = 0.001, p = 0.034; B = 0.007, p = 0.037).

CONCLUSION

Triglyceride and WC are the important metabolic syndrome factors associated with insulin resistance, basal β-cell function and insulin levels in non-diabetic FDR men of Type 2 DM patients. Moreover, FDRs showed insulin resistance with compensatory β-cell function (hyperinsulinaemia) suggesting that insulin resistance precede the development of pancreatic β-cell dysfunction in individuals at risk of Type 2 DM.

Protein glycation - biomarkers of metabolic dysfunction and early-stage decline in health in the era of precision medicine

Protein glycation provides a biomarker in widespread clinical use, glycated hemoglobin HbA1c (A1C). It is a biomarker for diagnosis of diabetes and prediabetes and of medium-term glycemic control in patients with established diabetes. A1C is an early-stage glycation adduct of hemoglobin with glucose; a fructosamine derivative. Glucose is an amino group-directed glycating agent, modifying N-terminal and lysine sidechain amino groups. A similar fructosamine derivative of serum albumin, glycated albumin (GA), finds use as a biomarker of glycemic control, particularly where there is interference in use of A1C. Later stage adducts, advanced glycation endproducts (AGEs), are formed by the degradation of fructosamines and by the reaction of reactive dicarbonyl metabolites, such as methylglyoxal. Dicarbonyls are arginine-directed glycating agents forming mainly hydroimidazolone AGEs. Glucosepane and pentosidine, an intense fluorophore, are AGE covalent crosslinks. Cellular proteolysis of glycated proteins forms glycated amino acids, which are released into plasma and excreted in urine. Development of diagnostic algorithms by artificial intelligence machine learning is enhancing the applications of glycation biomarkers. Investigational glycation biomarkers are in development for: (i) healthy aging; (ii) risk prediction of vascular complications of diabetes; (iii) diagnosis of autism; and (iv) diagnosis and classification of early-stage arthritis. Protein glycation biomarkers are influenced by heritability, aging, decline in metabolic, vascular, renal and skeletal health, and other factors. They are applicable to populations of differing ethnicities, bridging the gap between genotype and phenotype. They are thereby likely to find continued and expanding clinical use, including in the current era of developing precision medicine, reporting on multiple pathogenic processes and supporting a precision medicine approach.

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.

Field efficacy and safety of protamine zinc recombinant human insulin in 276 dogs with diabetes mellitus

Twice-daily (BID) insulin injections are a major deterrence to owners treating dogs with diabetes mellitus (DM). The hypothesis for this study was that Protamine Zinc Recombinant Human Insulin (PZIR) is safe and efficacious as a once-daily (SID) treatment for canine DM. This was a prospective, baseline-controlled, multi-center study over 182 ± 5 d. Two hundred seventy-six client-owned dogs with naturally occurring DM (naïve or pre-treated with insulin) were enrolled in the study. Enrollment was based upon demonstration of hyperglycemia, glycosuria, and ≥1 diabetic clinical sign (polyuria (PU), polydipsia (PD), or weight loss). Insulin treatment was initiated at 0.5-1.0 IU/kg SID. An improvement in at least one lab parameter related to DM (mean BG, min BG, Fructosamine) and one clinical parameter (PU/PD, body weight) was achieved in 72% of dogs (80% of naive, 62% of pre-treated). Dogs treated SID and BID showed improvement in 71% and 74% of cases, respectively. In naïve dogs, mean and minimum BG and fructosamine were significantly decreased (P < 0.05) by d 7 and 21, respectively, and in pre-treated dogs by d 63. By d 84, PU/PD improved in 90% and 88% of dogs, respectively, and the mean successful insulin dose was 1.4 IU/kg/d. Safety parameters were measured in 276 dogs for up to 182 d; clinical hypoglycemia occurred in 8.9% of dogs. We conclude that PZIR safely and effectively improved glycemic parameters and clinical signs in naïve and pre-treated diabetic dogs. The significant percentage of dogs on SID treatment with improvement in hyperglycemia and clinical signs confirms the prolonged action of PZIR in many dogs.

Increased body fat mass reduces the association between fructosamine and glycated hemoglobin in obese type 2 diabetes patients

Obesity is increasing in patients with type 2 diabetes. A possible reduced association between fructosamine and glycated hemoglobin (HbA1c) in obese individuals has been previously discussed, but this has never been specifically evaluated in type 2 diabetes, and the potential influence of body fat mass and fat distribution has never been studied. We studied 112 type 2 diabetes patients with assessment of fat mass, liver fat and fat distribution. Patients with body mass index (BMI) above the median (34.9 kg/m² ), versus BMI below the median, had a correlation coefficient between fructosamine and HbA1c significantly reduced (r = 0.358 vs r = 0.765). In the whole population, fructosamine was correlated negatively with BMI and fat mass. In multivariate analysis, fructosamine was associated with HbA1c (positively) and fat mass (negatively), but not with BMI, liver fat or fat distribution. The association between fructosamine and HbA1c is significantly reduced in the most obese type 2 diabetes patients, and this is mostly driven by increased fat mass.

Supplemental selenium and coenzyme Q10 reduce glycation along with cardiovascular mortality in an elderly population with low selenium status - A four-year, prospective, randomised, double-blind placebo-controlled trial

BACKGROUND

A low intake of selenium has been shown to increase the risk of cardiovascular mortality, and supplementation of selenium and coenzyme Q10 influences this. The mechanism behind is unclear although effects on inflammation, oxidative stress and microRNA expression have been reported. Fructosamine, a marker of long-term glycaemic control, is also a marker of increased risk of heart disease and death, even in non-diabetics.

OBJECTIVE

To analyse the impact of selenium and coenzyme Q10 supplementation on the concentration of fructosamine. Also, the relation between pre-intervention serum selenium concentration and the effect on fructosamine of the intervention was studied.

METHODS

Fructosamine plasma concentration was determined in 219 participants after six and 42 months of intervention with selenium yeast (200 μg/day) and coenzyme Q10 (200 mg/ day) (n = 118 of which 20 had diabetes at inclusion), or placebo (n = 101 of which 18 had diabetes at inclusion). Pre-intervention, the serum selenium levels were 67 μg/L (active treatment group: 66.6 μg/L; placebo group: 67.4 μg/L), corresponding to an estimated intake of 35 μg/day. Changes in concentrations of fructosamine following intervention were assessed by the use of T-tests, repeated measures of variance, and ANCOVA analyses.

RESULTS

Post-intervention selenium concentrations were 210 μg/L in the active group and 72 μg/L in the placebo group. A lower concentration of fructosamine could be seen as a result of the intervention in the total population (P = 0.001) in both the males (P = 0.04) and in the females (P = 0.01) in the non-diabetic population (P = 0.002), and in both the younger (<76 years) (P = 0.01) and the older (≥76 years) participants (P = 0.03). No difference could be demonstrated in fructosamine concentration in the diabetic patients, but the total sample was small (n = 38). In subjects with a low pre-intervention level of serum selenium the intervention gave a more pronounced decrease in fructosamine compared with those with a higher baseline selenium level.

CONCLUSION

A significantly lower concentration of fructosamine was observed in the elderly community-living participants supplemented with selenium and coenzyme Q10 for 42 months compared to those on the placebo. As oxidative mechanisms are involved in the glycation of proteins, less glycoxidation could be a result of the supplementation of selenium and coenzyme Q10, which could have contributed to lower cardiac mortality and less inflammation, as has earlier been reported. This study was registered at Clinicaltrials.gov, and has the identifier NCT01443780.

The agreement between fasting glucose and markers of chronic glycaemic exposure in individuals with and without chronic kidney disease: a cross-sectional study

Background

To assess whether the agreement between fasting glucose and glycated proteins is affected by chronic kidney disease (CKD) in a community-based sample of 1621 mixed-ancestry South Africans.

Methods

CKD was defined as an estimated glomerular filtration rate < 60 ml/min/1.73 m². Fasting plasma glucose and haemoglobin A1c (HbA1c) concentrations were measured by enzymatic hexokinase method and high-performance liquid chromatography, respectively, with fructosamine and glycated albumin measured by immunoturbidimetry and enzymatic method, respectively.

Results

Of those with CKD (n = 96), 79, 16 and 5% where in stages 3, 4 and 5, respectively. Those with CKD had higher levels of HbA1c (6.2 vs. 5.7%; p < 0.0001), glycated albumin (15.0 vs. 13.0%; p < 0.0001) and fructosamine levels (269.7 vs. 236.4 μmol/l; p < 0.0001), compared to those without CKD. Higher fasting glucose levels were associated with higher HbA1c, glycated albumin and fructosamine, independent of age, gender, and CKD. However, the association with HbA1c and glycated albumin differed by CKD status, at the upper concentrations of the respective markers (interaction term for both: p ≤ 0.095).

Conclusion

Our results suggest that although HbA1c and glycated albumin perform acceptably under conditions of normoglycaemia, these markers correlate less well with blood glucose levels in people with CKD who are not on dialysis.

Comparison of Serum Levels of Fructosamine and Erythrocyte Sodium Potassium ATPase (Na+/K+ ATPase) in Gestational Diabetes Mellitus (GDM) and non-Gestational Diabetes Mellitus (non GDM) Patients

BACKGROUND

The study aims at the comparison and correlation of serum levels of fructosamine and erythrocyte Na+/ K+ ATPase in Gestational diabetes mellitus (GDM) and Non Gestational Diabetes Mellitus (Non GDM).

METHODS

A total of 326 samples were divided into 4 groups. Pregnant women between the age group of 2040 years who gave samples for Oral Glucose Tolerance Test (OGTT) were included as the subjects. Anonymized and left over fasting and 2 hours' samples were collected from biochemistry laboratory, Kasturba Hospital, Manipal.

RESULTS

In the comparison of fructosamine levels in GDM and Non GDM, fructosamine was found to be significant (p value<0.001) in both fasting and 2 hours (G2) blood glucose condition. Na+/ K+ ATPase did not show any significant variation between the groups.Correlation was not significant between the parameters.

CONCLUSION

Fructosamine showed significant increase when compared between the groups, whereas significant correlation is not obtained between the parameters. Thus, the use fructosamine as a diagnosis tool becomes inconclusive. Further studies must be carried out to identify a marker which reduces the interferences observed in fructosamine and to find out the exact relationship between hyperglycaemia and Na+/ K+ ATPase activity.

Cannabidiol improves metabolic dysfunction in middle-aged diabetic rats submitted to a chronic cerebral hypoperfusion

Cannabidiol (CBD), a compound obtained from Cannabis sativa, has wide range of therapeutic properties, including mitigation of diabetes and neurodegeneration. Cerebral ischemia and consequent learning disabilities are aggravated in elderly diabetic subjects. However, there are no studies showing the effect of CBD treatment in elderly diabetes patients suffering cerebral ischemia. The present work tested the hypothesis that CBD treatment improves metabolic dysfunctions in middle-aged diabetic rats submitted to chronic cerebral hypoperfusion. In this work, 350-day-old male Wistar streptozotocin-induced diabetic rats were used. To induce cerebral ischemia was used a chronic cerebral hypoperfusion (CCH), surgically, via the four-vessel occlusion/internal carotid artery (4-VO/ICA). Four diabetic groups were established: Non-CCH Treated Diabetic (DNT), CCH Treated Diabetic (DCT), Non-CCH Vehicle Diabetic (DNV), and CCH Vehicle Diabetic (DCV). Vehicle groups were not treated with CBD. The animals were treated during 30 days with 10 mg CBD/Kg bw/day. After treatment, the animals were euthanized, and blood levels of glucose, insulin, total cholesterol, high density lipoprotein (HDL), low density lipoprotein (LDL), triglycerides, fructosamine, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were evaluated. DCT group presented reduction of hyperglycemia and an increase of insulinemia. Also was observed lower fructosamine, LDL, HDL, triglycerides and total cholesterol levels. AST and ALT concentration were reduced in CBD treated groups. CBD may be used as therapeutic tool to protect metabolism against injuries from diabetes aggravated by cerebral ischemia.

Serum fructosamine predicts macrosomia in well-controlled hyperglycaemic pregnant women: An observational cross-sectional study

AIM

While serum fructosamine may be a good marker of glucose control in pregnant women with diabetes, its relationship with macrosomia is still uncertain.

METHODS

In 130 hyperglycaemic women with singleton pregnancies (117 gestational diabetes mellitus, 13 pregestational diabetes), serum fructosamine and HbA1c levels were measured at 25±7 weeks of gestation. Levels in mothers of infants with and without macrosomic newborns (birth weight>4000g and/or large-for-gestational-age birth weight>90th percentile) were compared using logistic regression analysis adjusted for macrosomia risk factors.

RESULTS

These 130 pregnant women were 33±5 years old; their BMI before pregnancy was 27.7±6.9kg/m², and they gained 7.5±5.1kg during the first 6 months of gestation. Glucose control was good according to HbA1c levels (5.3±0.3%; 34±2mmol/mol), yet 17/130 (13%) newborns had macrosomia: 3900±227g vs 3057±512g (P<0.001) in the others. These mothers were older and had higher parity, whereas their BMI scores before pregnancy and gestational weight gains did not differ. Fructosamine levels were also higher at 221±40μmol/L vs 192±22μmol/l (P<0.001), respectively, and remained significant even after adjusting for maternal age, BMI, parity, type of diabetes, antecedents of macrosomia and excessive gestational weight gain. By contrast, HbA1c did not differ between the two groups. In fact, nearly two-thirds (64.7%) of the mothers of macrosomic newborns had fructosamine levels>200μmol/l vs 31.9% of mothers with non-macrosomic newborns (P<0.05).

CONCLUSION

High fructosamine levels are associated with macrosomia in the newborns of well-controlled hyperglycaemic pregnant women.

Association between glycated albumin, fructosamine, and HbA1c with neonatal outcomes in a prospective cohort of women with gestational diabetes mellitus

OBJECTIVE

To investigate whether glycated albumin, fructosamine, and hemoglobin A1c (HbA1c) are associated with neonatal complications in newborns of pregnant women with gestational diabetes mellitus (GDM).

METHODS

Between November 2016 and September 2017, women with a singleton pregnancy and GDM were enrolled in a prospective study in an obstetric Portuguese referral center. Glycemic markers were compared between mothers of newborns with and without complications. Multivariable logistic regression models and corresponding areas under the receiver operating characteristic curve (AUC) were used.

RESULTS

A total of 85 women participated in the study. Raised levels of glycated albumin and fructosamine were associated with at least one neonatal complication (OR- [odds ratio] estimate: 1.33, P=0.015; OR: 1.24, P=0.027, respectively) and with respiratory disorders at birth (OR 1.41, P=0.004; OR 1.26, P=0.014, respectively). HbA1c was not associated with these outcomes. All biomarkers were associated with large-for-gestational age (LGA) status (OR 1.61, P<0.001; OR 1.45, P<0.001; OR 3.62, P=0.032 for glycated albumin, fructosamine, and HbA1c, respectively). All had similar AUC for at least one neonatal complication (0.82; 0.81; 0.79, respectively). For newborn respiratory disorders, AUCs were 0.83, 0.81, and 0.76, respectively, and for LGA status were 0.81, 0.79, and 0.71, respectively.

CONCLUSION

Raised values of glycated albumin and fructosamine were associated with particular perinatal complications in newborns of mothers with GDM, better discriminating mothers of newborns with and without complications than HbA1c.

2019 John Insall Award: Fructosamine is a better glycaemic marker compared with glycated haemoglobin (HbA1C) in predicting adverse outcomes following total knee arthroplasty: a prospective multicentre study

AIMS

The best marker for assessing glycaemic control prior to total knee arthroplasty (TKA) remains unknown. The purpose of this study was to assess the utility of fructosamine compared with glycated haemoglobin (HbA1c) in predicting early complications following TKA, and to determine the threshold above which the risk of complications increased markedly.

PATIENTS AND METHODS

This prospective multi-institutional study evaluated primary TKA patients from four academic institutions. Patients (both diabetics and non-diabetics) were assessed using fructosamine and HbA1c levels within 30 days of surgery. Complications were assessed for 12 weeks from surgery and included prosthetic joint infection (PJI), wound complication, re-admission, re-operation, and death. The Youden's index was used to determine the cut-off for fructosamine and HbA1c associated with complications. Two additional cut-offs for HbA1c were examined: 7% and 7.5% and compared with fructosamine as a predictor for complications.

RESULTS

Overall, 1119 patients (441 men, 678 women) were included in the study. Fructosamine level of 293 µmol/l was identified as the optimal cut-off associated with complications. Patients with high fructosamine (> 293 µmol/l) were 11.2 times more likely to develop PJI compared with patients with low fructosamine (p = 0.001). Re-admission and re-operation rates were 4.2 and 4.5 times higher in patients with fructosamine above the threshold (p = 0.005 and p = 0.019, respectively). One patient (1.7%) from the elevated fructosamine group died compared with one patient (0.1%) in the normal fructosamine group (p = 0.10). These complications remained statistically significant in multiple regression analysis. Unlike fructosamine, all three cut-offs for HbA1c failed to show a significant association with complications.

CONCLUSION

Fructosamine is a valid and an excellent predictor of complications following TKA. It better reflects the glycaemic control, has greater predictive power for adverse events, and responds quicker to treatment compared with HbA1c. These findings support the screening of all patients undergoing TKA using fructosamine and in those with a level above 293 µmol/l, the risk of surgery should be carefully weighed against its benefit. Cite this article: Bone Joint J 2019;101-B(7 Supple C):3-9.

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.

A comparative analysis of fructosamine with other risk factors for kidney dysfunction in diabetic patients with or without chronic kidney disease

BACKGROUND

Hyperglycemia is the driving force for the development of diabetic nephropathy leading to the end stage renal disease. It is well known that in hyperglycaemic condition, serum proteins become glycated through non-enzymatic glycation. With the other risk factors, serum fructosamine may be an important risk factor for kidney impairment. To assess coexistence of frequently documented risk factors of kidney dysfunction with serum fructosamine in diabetic patients with chronic kidney disease (CKD).

METHODS

In this study, total 150 individuals, as control, type2 diabetic patients without complication and with CKD were included. Blood samples were collected from all the samples to estimate blood glucose, HbA1c, serum creatinine, fructosamine levels and lipid profile. Statistical analysis i.e. regression and correlation between serum fructosamine and other documented risk factors for diabetic CKD has been done. P < 0.001 was considered significant.

RESULTS

Serum fructosamine, HbA1c, creatinine levels, cholesterol and LDL were increased significantly (P < 0.001) in diabetic patients with CKD compared to without complications. Systolic and diastolic blood pressure and BMI were also significantly higher in diabetic patients compared to control. Serum creatinine, total cholesterol and LDL showed a significant positive correlation but HDL showed a negative correlation with fructosamine in CKD diabetic patients. No significant correlation was found with any risk factors in diabetic patients without complications expect HbA1c.

CONCLUSION

It is concluded that elevated serum fructosamine level is strongly associated with kidney dysfunction in diabetic patients. As there is a significant link between serum fructosamine and other risk factors for CKD diabetic patients.

Glucose, fructosamine, and insulin measurements in saliva of dogs: variations after an experimental glucose administration

The aim of this study was to evaluate if glucose, fructosamine, and insulin levels can be measured in saliva of dogs and assess the changes in these compounds after an experimental glucose administration. Automated spectrophotometric assays for glucose and fructosamine and an ELISA assay for insulin measurements were validated in saliva of dogs, by evaluating precision, accuracy, and limits of detection. In addition, an intravenous glucose bolus was administrated to 10 beagles and fasting serum and saliva samples were obtained immediately before and 5, 10, 20, 30, and 45 min after glucose infusion. The results of the between-run imprecision gave mean CVs of 6.16, 9.40, and 3.10% for glucose, fructosamine, and insulin, respectively. Linearity under dilution showed coefficient of correlation of 0.999, 0.994, and 0.990 for glucose, fructosamine, and insulin, respectively. The LDs were 0.04 mg/dL, 4.08 μmol/L, and 0.02 μg/mL for glucose, fructosamine, and insulin, respectively. The glucose administration caused an increase in serum and salivary levels of glucose with a peak in salivary levels at 30 min and of insulin with a peak in salivary levels at 45 min, while fructosamine did not change. No correlations between serum and salivary concentrations were found for any compound. It is concluded that glucose, fructosamine, and insulin can be measured in saliva of dogs, and an experimental administration of glucose in this species can lead to increases in glucose and insulin in saliva.

Establishing a blood fructosamine reference range for the Brazilian population based on data from ELSA - Brasil

Objectives

The fructosamine test is used in the monitoring of diabetes mellitus, particularly in cases with restrictions on the use of glycated hemoglobin (mainly in the setting of altered red blood cell lifespan and interference by hemoglobin variants). It could also provide additional information on shorter-term glycemic control. The objective of the study is to establish the reference range of the fructosamine in the Brazilian population.

Design and methods

The reference interval was defined as suggested by the Clinical and Laboratory Standards Institute (CLSI). The study participants were from a Brazilian cohort (The Longitudinal Study of Adult Health – ELSA-Brasil) with baseline data collected between 2008 and 2010. A total of 466 subjects were selected after exclusion of diabetic individuals, and those with altered glycemic markers and renal function tests.

Results

The reference interval was 186–248 μmol/L for women and 196–269 μmol/L for men. Fructosamine levels were higher in men than in women (p = 0.006) and in the non-white population (p = 0.034) and had a negative correlation with the body mass index (r = −0.117; p = 0.011).

Conclusions

The reference intervals for fructosamine were affected by sex. Reference intervals stratified by sex would be more adequate in the interpretation of the fructosamine test.

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Reference intervals for fructosamine in serum.

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The reference intervals for fructosamine were affected by sex.

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The reference intervals for fructosamine are different for different population.

Identification of differences in the formation of plasma glycated proteins between dogs and humans under diabetes-like glucose concentration conditions

Dogs have been proposed as a translational model and used for studying aging, diabetes, and diabetes-related complications in humans. However, no studies have ever compared the glycation of plasma proteins between dogs and humans under similar experimental conditions. Thus, the aim of this study was to fill this gap by comparing the plasma protein glycation patterns of dogs and humans in an ex-vivo system. Canine and human plasma samples were incubated with glucose at concentrations comparable to those observed in diabetic patients. The final glucose plasma concentration resulted in similar glucose:albumin ratios in both species. Glycated proteins were evaluated by measuring the content of fructosamine, protein carbonyls, and the formation of advanced glycation end-products (AGEs). The concentrations of fructosamine and protein carbonyls in canine and human plasma increased in a glucose concentration-dependent manner (P < 0.0001). Of note, the relative increment of fructosamine and protein carbonyl content and AGE formation was always higher in human than in dog plasma. Our results reveal that the plasma glycation processes in dogs and humans are not similar. These novel findings could contribute to improve our understating about canine and human diabetes as well as other condition associated in the glycation of proteins.

Clinical implication of alterations in serum Klotho levels in patients with type 2 diabetes mellitus and its associated complications

AIM

To investigate the clinical significance of serum α-Klotho and β-Klotho levels in patients with type 2 diabetes mellitus (T2DM) and its associated complications.

METHODS

Serum α-Klotho and β-Klotho levels were measured using an ELISA kit in 817 individuals, including 127 with T2DM, 106 with diabetic nephropathy, 99 with diabetic retinopathy, 108 with diabetic neuropathy, 102 with diabetic foot disease, 135 with T2DM and more than one complication and 140 healthy controls.

RESULTS

Both α-Klotho and β-Klotho levels were significantly decreased in the T2DM group and the groups with associated complications compared with the levels in control group. The differences between the T2DM group and the T2DM with complications groups were not significant, except between the diabetic nephropathy group and the other diabetic complications groups. In addition, α-Klotho and β-Klotho levels were negatively correlated with serum fructosamine and HbA1c but were not associated with serum glucose in the model including all participants. Moreover, decreases in α-Klotho and β-Klotho levels in the high glucose-exposed cell culture model, which was dependent on glucose exposure time, were confirmed.

CONCLUSIONS

Levels of α-Klotho and β-Klotho were downregulated in patients in the T2DM and complications groups. Our findings indicate that serum Klotho levels were associated with the development of T2DM, and long-term control of blood glucose will be beneficial in ameliorating changes to α-Klotho and β-Klotho levels in patients with T2DM and complications.

A proof-of-concept study to evaluate the efficacy and safety of BTI320 on post-prandial hyperglycaemia in Chinese subjects with pre-diabetes

BACKGROUND

Galactomannan(s) are plant-derived fiber shown to reduce post-prandial blood glucose by delaying intestinal absorption of carbohydrates and slowing down gastric emptying. We examined glucose-lowering effects of BTI320, a propriety fractionated mannan(s) administered as a chewable tablet before meal in a proof-of-concept study in Chinese subjects with prediabetes.

METHODS

Sixty Chinese adults aged 18-70 years with either impaired fasting glucose, impaired glucose tolerance, or glycated haemoglobin 5.7-6.4% (39-46 mmol/mol), were randomly assigned in 2:2:1 ratio to either BTI320 8 g (high dose), BTI320 4 g (low dose) or matching-placebo three times daily before meal for 16 weeks. The primary endpoint was change in fructosamine in subjects treated with BTI320 compared with placebo from baseline to week 4. Indices of glycaemic variability based on continuous glucose monitoring (CGM) and standard meal tolerance test were explored in secondary analyses.

RESULTS

Of 60 subjects randomized, 3 subjects discontinued study treatment prematurely. In intention-to-treat analysis, no significant differences in change in serum fructosamine between low or high dose BTI320 and placebo were observed. Using random effect models, adjusted for variability by meals, treatment with low dose BTI320 was associated with reduction in 1-h (p < 0.01), 2-h (p = 0.01) and 3-h (p = 0.02) post-prandial incremental glucose area-under-curve and post-meal maximum glucose (p = 0.03) compared with placebo. Subjects receiving low dose BTI320 had greater body weight reduction than placebo group.

CONCLUSIONS

BTI320 did not change fructosamine levels compared with placebo. BTI320 reduced glycaemic variability based on CGM indices.

TRIAL REGISTRATION

The study was registered at www.clinicaltrials.gov , reference number NCT02358668 (9 February 2015).

Temporal relationships of GH, IGF-I and fructosamine concentrations in pregnant Spanish Purebred mares: A substantial contribution from the hormonal standpoint

Growth hormone (GH) and insulin-like growth factor (IGF-I) exert essential functions to maintain an adequate metabolic activity for correct placental and fetal development. Although fructosamine (FRUCT) is used in clinical evaluation to assess the glycaemic state, the relationships between GH, IGF-I and FRUCT remain unknown in the mare. Therefore, the objectives of this study were to evaluate the relationships among these parameters in pregnant mares. A total of 30 healthy Spanish Purebred mares, with an age range of 9.33 ± 3.31 years, were studied during the 11 months of gestation. Serum concentrations of GH, IGF-I and FRUCT were analyzed by EIA, competition ELISA and spectrophotometry, respectively. GH showed a biphasic pattern, the first occurred during 4th and 5th month and the second which was higher than the 1st one during the 7th, 8th and 9th month (P < 0.05). Compared to the 1st month, the IGF-I concentrations increased in the 2nd month (P < 0.05), decreased in the 3rd and 4th month and increased to reach the maximum average value in the 5th month (P < 0.05); after slight oscillations between the 6th and 8th month, IGF-I concentrations increased in the 9th month (P < 0.05), decreasing until the end of gestation. FRUCT increased progressively and significantly from the 6th month of gestation, reaching the maximum values in the last month of gestation (P < 0.05). These results suggest that alternative mechanisms other than GH and IGF-I could be involved in the regulation of glycaemic metabolism in pregnant mare.

Haemoglobin A1c or Glycated Albumin for Diagnosis and Monitoring Diabetes: An African Perspective

Diabetes mellitus (DM) has reached epidemic proportions across the globe with the largest increases seen in sub-Saharan Africa. Those that are diagnosed are largely poorly controlled. This review summarizes the limitations of the use of glycated haemoglobin (HBA1c) in Africa and current knowledge on the utility of glycated albumin and fructosamine in African patients. The diagnosis and monitoring of DM in African patients may be compromised by associated conditions like sickle cell anaemia, chronic kidney disease and HIV infection. Glycated albumin reflects short term glycaemia and is not affected by many conditions that alter HbA1c. It can be measured enzymatically, and this review discusses methods for analysis, and discusses the advantages and limitations in specific situations with an emphasis on conditions that also affect HbA1c.

Glycated albumin in chronic kidney disease: Pathophysiologic connections

Nephropathy in diabetes patients is the most common etiology of end-stage kidney disease (ESKD). Strict glycemic control reduces the development and progression of diabetes-related complications, and there is evidence that improved metabolic control improves outcomes in subjects having diabetes mellitus with advanced chronic kidney disease (CKD). Glycemic control in people with kidney disease is complex. Changes in glucose and insulin homoeostasis may occur as a consequence of loss of kidney function and dialysis. The reliability of measures of long-term glycemic control is affected by CKD and the accuracy of glycated haemoglobin (HbA1c) in the setting of CKD and ESKD is questioned. Despite the altered character of diabetes in CKD, current guidelines for diabetes management are not specifically adjusted for this patient group. The validity of indicators of long-term glycemic control has been the focus of increased recent research. This review discusses the current understanding of commonly used indicators of metabolic control (HbA1c, fructosamine, glycated albumin) in the setting of advanced CKD.

Managing Diabetes and Cardiovascular Risk in Chronic Kidney Disease Patients

We discuss mechanisms of increased cardiovascular disease (CVD) in patients with chronic kidney disease (CKD) and strategies for managing cardiovascular (CV) risk in these patients. Our focus was mainly on decreasing CV events and progression of microvascular complications by reducing levels of glucose and lipids. We searched PubMed with no limit on the date of the article. All articles were discussed among all authors. We chose pertinent articles, and searched their references in turn for additional relevant publications.

In Vitro Inhibitory Activity of Acca sellowiana Fruit Extract on End Products of Advanced Glycation

INTRODUCTION

Hyperglycemia plays an important role in the pathogenesis of diabetic complications, as it increases protein glycation, as well as the progressive accumulation of advanced glycation end products (AGEs), which are complex structures that produce fluorescence. The glycation reaction raises the levels of protein carbonyl, N ^ε-(carboxymethyl)lysine (CML), and fructosamine and decreases the level of thiol groups.

METHODS

In the present study, the antiglycation activity was determined by fluorescence intensity using the bovine serum albumin (BSA)/glucose, CML method, and the level of fructosamine. The oxidation of proteins was determined by the carbonyl protein content and thiol groups.

RESULTS

The results show that the hexane extract of Acca sellowiana (FOH) at different concentrations (0.30-5 mg/ml) significantly inhibited the formation of AGEs in the BSA/glucose model during the 4 weeks of the study. FOH reduced the levels of fructosamine and CML. Our results showed a significant effect of FOH in the prevention of oxidative damage of proteins, as well as an effect on the oxidation of thiol groups and carbonyl proteins.

CONCLUSION

The present study indicates that FOH is effective in inhibiting the glycation of proteins in vitro, so it can prevent or ameliorate the chronic conditions of diabetes associated with the formation of AGEs.

Concordance the hemoglobin glycation index with glycation gap using glycated albumin in patients with type 2 diabetes

BACKGROUND

The hemoglobin glycation index (HGI) is an index of differences in the glycation of hemoglobin according to blood glucose level. The glycation gap (G-gap) is an empiric measure of the extent of disagreement between hemoglobin A1C (HbA1C) and glycated albumin (GA). The aim of this study was to investigate the extent of agreement between the HGI and G-gap with respect to GA level, and to elucidate factors related to a high HGI.

METHOD

Data were obtained from 105 patients with type 2 diabetes, and fasting blood glucose (FBG), HbA1c, and GA values were measured simultaneously. The G-gap was calculated as the difference between the measured and GA-based predicted HbA1c levels. HGI was calculated as the difference between measured and FBG-based predicted HbA1c levels.

RESULTS

The HGI and G-gap were highly correlated according GA (r=0.722, P<0.001). In general, the two indices were similar in terms of both direction and magnitude. The classification of patients as high, moderate, or low glycators based on HGI versus G-gap was consistent for the majority of the population and only 5% of patients were reclassified from high to low or low to high. Fasting C-peptide levels decreased linearly, and the percentage of patients using insulin increased linearly, between the lowest and highest HGI tertile (both P<0.05).

CONCLUSIONS

There was 95% agreement between the HGI and G-gap using GA among type 2 diabetes patients. Furthermore, a high HGI was associated with a higher prevalence of insulin use among type 2 diabetes patients.

Alternative indices of glucose homeostasis as biochemical diagnostic tests for abnormal glucose tolerance in an African setting

AIMS

Accurate diabetes diagnosis is important in Africa, where rates are increasing, and the disease largely undiagnosed. The cumbersome oral glucose tolerance test (OGTT) remains the reference standard, while alternative diagnostic methods are not yet established in Africans. We assessed the ability of fasting plasma glucose (FPG), HbA1c and fructosamine, to diagnose OGTT-based abnormal glucose tolerance in mixed-ancestry South Africans.

METHODS

Mixed-ancestry adults, residing in Cape Town were examined between February and November 2015. OGTT values were used to classify glucose tolerance status as: screen-detected diabetes, prediabetes, dysglycaemia (combination of diabetes and prediabetes) and normal glucose tolerance.

RESULTS

Of the 793 participants included, 65 (8.2%) had screen-detected diabetes, 157 (19.8%) prediabetes and 571 (72.0%) normal glucose tolerance. Correlations of FPG and 2-h glucose with HbA1c (r=0.51 and 0.52) were higher than those with fructosamine (0.34 and 0.30), both p<0.0001. The highest c-statistic for the prediction of abnormal glucose tolerance was recorded with 2-h glucose [c-statistic=0.997 (screen-detected diabetes), 0.979 (prediabetes) and 0.984 (dysglycaemia)] and the lowest with fructosamine (0.865, 0.596 and 0.677). At recommended or data-specific optimal cut-offs, no combination of FPG, HbA1c and fructosamine did better than 2-h glucose, while FPG was better than HbA1c and fructosamine on a range of performance measures.

CONCLUSIONS

Abnormal glucose tolerance in this population is overwhelmingly expressed through 2-h glucose's abnormalities; and no combination of FPG, HbA1c and fructosamine was effective at accurately discriminating OGTT-defined abnormal glucose tolerance. Tested non-glucose based strategies are unreliable alternatives to OGTT for dysglycaemia diagnosis in this population.

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

BACKGROUND AND AIMS

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

METHODS AND RESULTS

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

CONCLUSION

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

Serum fructosamine, serum glycated albumin and serum glycated β-lipoprotein in type 2 diabetes mellitus patients with and without microvascular complications

Background

Glycation of serum proteins has been proposed as an important mechanism of complications of diabetes but whether there are differences in glycation of different serum proteins and whether it has any correlation with development of microvascular complications has not been studied in depth. This study aimed to assess level of serum fructosamine, glycated albumin and glycated β-lipoprotein in type 2 diabetes mellitus patients with and without microvascular complications and to find out their correlation with diabetes complications.

Methods

Case–control study involving 150 individuals at a tertiary care hospital in western India. Fifty participants were healthy controls (group 1), 50 were type 2 diabetes patients without any evident microvascular complication (group 2) and 50 were type 2 diabetes patients with one or more microvascular complications (group 3). Serum fructosamine, FBS, PP2BS and other biochemical parameters were measured. Glycated albumin and glycated β-lipoprotein were measured by agarose gel electrophoresis followed by NBT staining. Unpaired t-test was used to find out significance of difference between two groups and correlation coefficient to find out statistical correlation between two variables.

Results

Type 2 diabetes patients with one or more microvascular complications had poor glycemic control as indicated by markers of short and mid-term glycemia. Differences between the groups for fructosamine, glycated albumin and glycated β-lipoprotein were significant (p < 0.001). Glycated albumin correlated with FBS, PP2BS and fructosamine in all diabetic patients (group 2 and 3) whereas glycated β-lipoprotein correlated with these parameters only in group 3 and it was markedly elevated in group 3.

Conclusion

Serum glycated β-lipoprotein was disproportionately elevated compared to fructosamine and glycated albumin in diabetes patients with microvascular complications (group 3) and it correlated with rest of glycemic markers only in this group. Glycated β-lipoprotein might help in identifying diabetic individuals at high future risk of developing microvascular complications.

Glycation in human fingernail clippings using ATR-FTIR spectrometry, a new marker for the diagnosis and monitoring of diabetes mellitus

OBJECTIVES

Although HbA1c is a good diagnostic tool for diabetes, the precarity of the health system and the costs limit the use of this biomarker in developing countries. Fingernail clippings contain ±85% of keratins, which are prone to glycation. Nail keratin glycation may reflect the average glycemia over the last months. We explored if attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) can be used as a non-invasive tool for assessing glycation in diabetes.

DESIGN AND METHODS

Using ATR-FTIR spectroscopy, glycation and deglycation experiments with fructosamine 3-kinase allowed to identify the spectrum that corresponds with keratin glycation in fingernail clippings. Clippings of 105 healthy subjects and 127 diabetics were subjected to the standardized ATR-FTIR spectroscopy method.

RESULTS

In vitro glycation resulted in an increased absorption at 1047cm^-1. Following enzymatic deglycation, this peak diminished significantly, proving that the AUC between 970 and 1140cm^-1 corresponded with glycated proteins. Within-run CV of the assay was 3%. Storage of nail clippings at 37°C for 2weeks did not significantly change results. In diabetics, glycated nail protein concentrations (median: 1.51μmol/g protein, IQR: 1.37-1.85μmol/g protein) were significantly higher than in the controls (median: 1.19μmol/g protein, IQR: 1.09-1.26μmol/g protein) (p<0.0001). ROC analysis yielded an AUC of 0.92 at a cut-off point of 1.28μmol/g nail (specificity: 82%; sensitivity: 90%). No correlation was observed between the glycated nail protein concentrations and HbA1c.

CONCLUSIONS

Protein glycation analysis in fingernails with ATR-FTIR spectroscopy could be an alternative affordable technique for diagnosing and monitoring diabetes. As the test does not consume reagents, and the preanalytical phase is extremely robust, the test could be particularly useful in developing countries.

Do glycemic marker levels vary by race? Differing results from a cross-sectional analysis of individuals with and without diagnosed diabetes

OBJECTIVE

It is well known that A1c varies by race. However, racial differences in other biomarkers of hyperglycemia are less well characterized. The objective of this study was to determine whether average levels of glycemic markers differ by race in adults with and without diagnosed diabetes, before and after accounting for postchallenge glucose.

RESEARCH DESIGN AND METHODS

This cross-sectional study included 2692 middle-aged men and women (5.5% with diagnosed diabetes; 44% African-American; and 56% white) from the Coronary Artery Risk Development in Young Adults Study (2005-2006) who had fasting glucose, 2-hour postchallenge glucose, A1c, glycated albumin, fructosamine, and 1,5-anhydroglucitol (1,5-AG) measured. Multiple linear regression was used to evaluate racial differences in mean levels of each glycemic marker stratified by the diabetes status and adjusted for sociodemographics, cardiovascular factors, and postchallenge glucose.

RESULTS

Among those with diagnosed diabetes, racial differences were not observed for any of the glycemic markers. In contrast, among those without diagnosed diabetes, African-Americans had higher mean levels than whites of A1c (β=0.19% points; 95% CI 0.14 to 0.24), glycated albumin (β=0.82% points; 95% CI 0.68 to 0.97), fructosamine (β=8.68 μmol/L; 95% CI 6.68 to 10.68), and 2-hour glucose (β=3.50 mg/dL; 95% CI 0.10 to 6.90) after multivariable adjustment, whereas there were no statistically significant racial difference in 1,5-AG. The racial differences observed for A1c, glycated albumin, and fructosamine persisted after further adjustment for fasting and 2-hour glucose and were of similar magnitude (SD units).

CONCLUSIONS

Racial differences in glycemic marker levels were evident among middle-aged adults without diagnosed diabetes even after adjustment for postchallenge glucose. Whether these racial differences in biomarkers of hyperglycemia affect the risk of complications warrants additional study.

Discordance in the levels of hemoglobin A1C and glycated albumin: Calculation of the glycation gap based on glycated albumin level

OBJECTIVE

The glycation gap (G-gap) is an empirical measure of the extent of the difference between HbA1C and fructosamine levels. Several studies have shown that the presence of a G-gap is linked to diabetic nephropathy, but possible artifacts caused by dependence of the fructosamine level on the extent of serum protein metabolism require careful consideration. We investigated the consistency of G-gaps measured by assaying glycated albumin (GA) levels to identify factors associated with G-gap variations.

METHOD

A total of 457 pairs of observations, like an HbA1c and GA measurement at the same clinic visit, were obtained from 170 Korean patients with type 2 diabetes. HbA1c and GA levels were measured simultaneously in two or three separate occasions. Each G-gap was calculated as the difference between the measured HbA1c level and that predicted by the GA level. All patients underwent abdominal computed tomography, and the areas of subcutaneous and visceral fat were measured.

RESULTS

The G-gaps were all significantly inter-correlated over time (γ=0.755, P<0.001).The direction of each G-gap was consistent. The body mass index (BMI), visceral fat area, and the estimated glomerular filtration rate (eGFR) increased linearly from the lowest to the highest G-gap quartile (all P values <0.05). Upon multivariate analysis, both visceral fat area and the eGFR were significantly associated with a G-gap.

CONCLUSIONS

A G-gap determined using GA measurements is consistent within an individual over time. The G-gap is associated with visceral fat and kidney function in patients with type 2 diabetes.

The impact of intra-articular methylprednisolone acetate injection on fructosamine levels in diabetic patients with osteoarthritis of the knee, a case-control study

Fructosamine is a glycated protein that reflects blood glucose control over the last 2-3 weeks. There are no studies that address the impact of intra-articular injection (IAI) of methylprednisolone acetate (MPA) on fructosamine levels among patients with type-2 diabetes and osteoarthritis of the knee (OAK). Non-selected patients attending the rheumatology or orthopedic clinic with type-2 diabetes and painful OAK, who failed non-steroidal anti-inflammatory drugs (NSAIDS) and physical therapy, were asked to participate in our study. After consent blood tests were drown for fructosamine, hemoglobin A1c (HbA1c) level, complete blood count, lipid profile, serum albumin, serum protein, c-reactive protein, and erythrocyte sedimentation rate. Demographic and different clinical parameters were also documented. Immediately after that, patients had IAI of 80 mg of MPA at the knee joint (group 1). Two to three weeks later, the same blood tests were repeated (except for HbA1c). Age- and sex-matched group of patients with type-2 diabetes and painful OAK attending the same clinics, but who were managed by NSAIDS were asked to participate as a control group (group 2) and had the same evaluation at enrollment and 2-3 weeks later, after consent. Eighteen patients from either group completed the study. Mean fructosamine level in group 1 patients was 263.7 ± 31.8 mg% prior to the IAI vs. 274.6 ± 39.3 mg% (p = 0.035), 2-3 weeks later, while mean fructosamine level in the control group (group 2) at enrollments was 274.2 ± 31.2 mg% vs. 269 ± 30.2 mg%, p = 0.509, 2-3 weeks later. There was no significant change in any other parameter tested at enrollment in either group, compared to those obtained 2-3 weeks afterwards. Body mass index was on the edge of significance as a predictor for a significant change in fructosamine level in group 1 patients. IAI of 80 mg of MPA in patients with type-2 diabetes and OAK had resulted in a significant, though mild increase in fructosamine levels 2-3 weeks later.

Rational diagnoses of diabetes: the comparison of 1,5-anhydroglucitol with other glycemic markers

Diabetes mellitus (DM) is a frequently encountered disease with important morbidity and mortality. The aim of this study is to document the importance of 1,5-anhydroglucitol (1,5-AG) for the diagnosis of prediabetes and DM, as well as to compare the 1,5-AG with other glycemic markers in order to understand which one is the better diagnostic tool. Between April 2012 and December 2012, 128 participants enrolled in the study. Participants were split into five groups that are IFG, IGT, IFG+IGT, diabetic and control groups by their OGTT results. The diagnostic value of markers was compared by ROC (receiver operating characteristic) method. The mean serum 1,5-AG levels in the diabetic group (33.38 nmol/ml) were lower than, IFG (59.83 nmol/ml), IGT (54.44 nmol/ml), IFG+IGT (51.98 nmol/ml) and control groups (73.24 nmol/ml). When analyzed in the total study population serum 1,5-AG levels did not differ by gender significantly. When analyzed in the total study population, 1,5-AG correlates inversely with age significantly (p = 0.036). In subgroup analysis, in the control group, serum 1,5-AG level was also inversely correlated with age (p = 0.087). The best marker for the diagnosis of prediabetes and DM was fasting plasma glucose (FPG). 1,5-AG was not found to be effective for the diagnosis of DM. This study, contributes to our knowledge of the efficiency and cut-off values of 1,5-AG for the diagnosis of prediabetes and DM. In future, there is a need for larger studies with more standardized and commonly used measurement methods for 1,5-AG, in order to evaluate the efficiency of 1,5-AG for the diagnosis of prediabetes and DM.

Fructosamine is a risk factor for myocardial infarction and all-cause mortality - Longitudinal experience from the AMORIS cohort

BACKGROUND AND AIMS

Glycation is linked to microvascular complications of diabetes and also to macrovascular events. Fructosamine is a biomarker of glycation but its associations to macrovascular complications are not well documented. The aim of this study was to evaluate fructosamine as a predictor of myocardial infarction and all-cause mortality in a large population based cohort.

METHODS AND RESULTS

Information on glucose and fructosamine was obtained from subjects of the AMORIS cohort (n = 338,443) followed for 19 years on average. Incident cases of myocardial infarction and death from any cause were identified from national patient and cause of death register respectively. The incidence of myocardial infarction (n = 21,526 cases) and all-cause mortality (n = 73,458 deaths) increased at a fructosamine of 2.30 mmol/L or above. For myocardial infarction, the sex-age- fasting- and entry period adjusted hazard ratio in subjects above 2.70 mmol/L vs. reference range subjects was 2.88 (95% CI: 2.70-3.07). The corresponding hazard ratio for all-cause mortality was 2.31 (95% CI: 2.21-2.41). These associations remained basically unchanged after adjustment for total cholesterol, triglycerides, albumin, social class, smoking and hypertension. When additional adjustment for glucose was performed the associations were attenuated but remained. In a sub cohort with simultaneous measurements of fructosamine, HbA1c and fasting glucose respectively similar associations were observed (n = 9746).

CONCLUSION

There is a strong association between fructosamine and myocardial infarction and death from any cause when major cardiovascular risk factors are accounted for. In addition, this association could only partly be explained by glucose levels.