Low HbA1c Concentrations Research Articles

A Boronate Affinity-Assisted SERS Tag Equipped with a Sandwich System for Detection of Glycated Hemoglobin in the Hemolysate of Human Erythrocytes.

Phenylboronic acid-functionalized, Ag shell-coated, magnetic, monodisperse polymethacrylate microspheres equipped with a glycoprotein-sensitive sandwich system were proposed as a surface-enhanced Raman scattering (SERS) substrate for quantitative determination of glycated hemoglobin (HbA1c). The magnetization of the SERS tag and the formation of the Ag shell on the magnetic support were achieved using the bifunctional reactivity of newly synthesized polymethacrylate microspheres. The hemolysate of human red blood cells containing both HbA1c and nonglycated hemoglobin was used for determination of HbA1c. The working principle of the proposed SERS tag is based on the immobilization of HbA1c by cyclic boronate ester formation between glycosyl residues of HbA1c and boronic acid groups of magnetic polymethacrylate microspheres and the binding of p-aminothiophenol (PATP)-functionalized Ag nanoparticles (Ag NPs) carrying another boronic acid ligand via cyclic boronate ester formation via unused glycosyl groups of bound HbA1c. Then, in situ formation of a Raman reporter, 4,4'-dimercaptoazobenzene from PATP under 785 nm laser irradiation allowed for the quantification of HbA1c bound onto the magnetic SERS tag, which was proportional to the HbA1c concentration in the hemolysate of human erythrocytes. The sandwich system provided a significant enhancement in the SERS signal intensity due to the plasmon coupling between Ag NPs and Ag shell-coated magnetic microspheres, and low HbA1c concentrations down to 50 ng/mL could be detected. The calibration curve obtained with a high correlation coefficient between the SERS signal intensity and HbA1c level showed the usability of the SERS protocol for the determination of the HbA1c level in any person.

Pediatric Diabetes Consortium Type 1 Diabetes New Onset (NeOn) Study: factors associated with HbA1c levels one year after diagnosis

To identify determinants of hemoglobin A1c (HbA1c) levels 1 yr after the diagnosis of type 1 diabetes (T1D) in participants in the Pediatric Diabetes Consortium (PDC) T1D New Onset (NeOn) Study. Diabetes-specific as well as socioeconomic factors during the first year following diagnosis were analyzed in 857 participants (mean age 9.1 yrs, 51% female, 66% non-Hispanic White) not participating in an intervention study who had an HbA1c value at 12 months. Mean ± SD HbA1c at 1 yr was 62 ± 16 mmol/mol (7.8% ± 1.5). In univariate and multivariate analyses, clinical center, non-Hispanic White race, private health insurance, living with both parents, higher frequency of self-monitoring of blood glucose (SMBG), and lower insulin requirements were associated with lower HbA1c concentrations at 1 yr (p < 0.01). No association was found with gender, age, Tanner stage, body mass index (BMI), diabetic ketoacidosis (DKA) at onset, number of positive autoantibodies or HbA1c at onset, or number of visits to diabetes physician during the first year. White race, higher socioeconomic status, two-parent household, more frequent SMBG, and low insulin requirements are associated with lower HbA1c concentration 1 yr after the onset of T1D in children.

Pitfalls of Glycated Hemoglobin in the Glycemic Assessment of Diabetes Patients with Hemoglobin Louisville: Role of Serum Fructosamine

Measurement of glycated hemoglobin (HbA1c) is widely used in the management of patients with diabetes mellitus (DM). We report on three patients with a history of type 2 DM and consistent elevation of fasting blood glucose values, but with falsely low HbA1c values. Fasting blood glucose measurements were made using the hexokinase method in a Cobas 6000 (Roche Diagnostics, Rotkreuz, Switzerland). Determinations of HbA1c were performed on ethylenediaminetetraacetic acid–anticoagulated blood sample by two methods: high-performance liquid chromatography (HPLC) (HA-8160 in diabetic mode, A. Menarini Diagnostics, Florence, Italy), which detected no abnormal hemoglobin (Hb); and immune-turbidimetric method (Tina-quant Hemoglobin A1c Gen3 in a Cobas 6000), which was used for two patients. Both methods were calibrated according to the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) Reference Measurement Procedure. Results are shown in Table 1. Table 1 Results of Three Patients with Hb Louisville All three patients had evidence of hemolytic anemia, and their average Hb levels were as follows: patient A: 9.41 g/dl, patient B: 10.9 g/dl, patient C: 8.6 g/dl. Abnormally low HbA1c concentrations are usually encountered in patients with high turnover rates of hemoglobin.1 Further investigations revealed that the patients belonged to the same family, and all three had a history of heterozygosity trait for Hb Louisville.2 Hemoglobin Louisville is an unstable Hb that differs from HbA by the substitution of a phenylalanine residue for a leucine residue in position 42 of the β globin chain, resulting in instability in the Hb molecule, with increased erythrocyte destruction, and clinically manifested as hemolytic anemia2. The Hb Louisville heterozygotes suffer from mild anemia, jaundice, and hemolytic crisis. Upon testing our patients, the abnormal Hb could not be separated from normal HbA by electrophoresis method,3 but interference in the HbA2 zone was noted using the HLPC Bio-Rad D-10TM Dual Program, extended program. As hemolytic anemia causes decreased exposure time of Hb to glucose, the result is a decreased percentage of Hb undergoing glycation.4 Fructosamine is neither affected by disorders of red blood cells nor influenced by Hb variants; thus serving as an indicator of blood glucose concentrations for the previous 2 to 3 weeks. Serum fructosamine level determination is advocated in patients with red blood cell disorders or with discrepancies between glucose measurements and HbA1c values.5 We therefore determined fructosamine levels with a colorimetric test using nitriblue tetrazolium in alkaline solution, with the following results: patient A (patient deceased); patient B: 420 μmol/liter (in a previous test 391 μmol/dl); and patient C: 295 μmol/liter (reference range >285 μmol/liter). Physicians need to be aware of the factors that can influence laboratory HbA1c levels, as therapeutic decisions are often based on these measurements. In diabetes patients who are Hb Louisville carriers, glycemic control should be monitored with serial glucose determinations or by fructosamine level.

Serum Fructosamine As an Alternative to Glycated Hemoglobin (HbA1c) for Glycemic Assessment in Diabetic Patients with Hemoglobin (Hb) Louisville

AbstractAbstract 4771 Background:HbA1c is widely used in the management of patients with diabetes mellitus (DM). Hb Louisville is an unstable hemoglobin that differs from HbA by the substitution of a phenylalanine residue for a leucine residue in position 42 of the b-chain, resulting in instability in the Hb molecule with increased erythrocytic destruction, clinically manifested as hemolytic anemia. The Hb Louisville heterozygotes suffer from a mild anemia, jaundice and hemolytic crisis. Abnormally low HbA1c concentrations are usually encountered in patients with high turnover rates of hemoglobin. Fructosamine is unaffected by disorders of red blood cells nor is influenced by hemoglobin variants, thus serving as an indicator of blood glucose concentrations of previous 2–3 weeks. Methods:Case report. Results:We report on three patients that belonged to the same family and had history of heterozygosity trait for Hb Louisville. All three patients had type 2 diabetes mellitus with falsely low HbA1c values (patient A: 2.8%, 2.9%, 3.2%; patient B: 4.4%, 3.8%, 3.7%; patient C: 4.2%, 4.6%, 3.7%). The patients had consistent elevation of fasting blood glucose values (patient A: 162, 171, 233 mg/dL; patient B: 262, 232, 235 mg/dL; patient C: 152, 130, 136 mg/dL). All three patients had evidence of hemolytic anemia, and their average hemoglobin levels were: patient A: 9.41 mg/dL, patient B: 10.9 mg/dL, patient C: 8.6 mg/dL. We therefore determined serum fructosamine levels, and the results were: patient A (patient deceased), patient B: 420 mcmol/L and patient C: 295 mcmol/L (Reference Range >285 mcmol/L). Conclusion:Fructosamine serum level determination is advocated for glycemic assessment in diabetic patients with Hb Louisville when discrepancies between glucose measurements and HbA1c values>are encountered. Disclosures:No relevant conflicts of interest to declare.

Evaluation of the Menarini/ARKRAY ADAMS A1c HA-8180V analyser for HbA1c

We report an evaluation of the Menarini/ARKRAY ADAMS A1c HA-8180V analyser (HA-8180V), the fifth generation Menarini/ARKRAY ion-exchange HPLC for the measurement of HbA(1c). We evaluated the analytical performance, the measurement of haemoglobin variants and the performance in comparison to major analytical methods. Within-run, between-run and total CV were 0.2%, 0.4% and 0.7% at low HbA(1c) concentrations and 0.2%, 0.2% and 0.4% at high HbA(1c) concentrations, respectively. Trueness revealed a maximum deviation of 0.8 mmol/mol (IFCC units) or 0.1% (NGSP units) over the relevant analytical range. Linearity, carry-over and linear drift were excellent. Labile-HbA(1c), carbamylated haemoglobin, icteric samples and variation in hematocrit did not affect HbA(1c) outcome. Haemoglobin variants AS, AC and F do not affect HbA(1c) outcome and are explicitly identified and correctly quantified. HbA(1c) can not be measured in samples with AE and AD, but these variants are identified correctly. In comparison to other methods used at present, the HA-8180V shows excellent performance. The HA-8180V performs at a high level and is fit for any clinical application.

Four-year metabolic outcome of a randomised controlled CD3-antibody trial in recent-onset type 1 diabetic patients depends on their age and baseline residual beta cell mass

The aim of the study was to examine the 48 month outcome of treating recent-onset type 1 diabetic patients for 6 days with humanised CD3-antibody, ChAglyCD3. Eighty patients, aged 12-39 years, were recruited for a phase 2 multicentre trial and randomised to placebo (n=40) or ChAglyCD3 (n=40) treatment by a third party member; participants and care-givers were blinded. The change in insulin dose (U kg(-1)day(-1)) over 48 months was chosen as primary endpoint and compared in 31 placebo-and 33 ChAglyCD3-treated patients. Adverse events were followed in 35 and 38 patients, respectively. Treatment with ChAglyCD3 delayed the rise in insulin requirements of patients with recent-onset diabetes and reduced its amplitude over 48 months (+0.09 vs +0.32 U kg(-1)day(-1) in the placebo group). Using multivariate analysis this effect was correlated with higher baseline residual beta cell function and a younger age. It was associated with better outcome variables in subgroups selected according to these variables. In the ChAglyCD3 subgroup with higher initial beta cell function, 0/11 patients became C-peptide-negative over 48 months vs 4/9 in the corresponding placebo subgroup. In the subgroup aged <27 years old, antibody treatment preserved initial beta cell function for 36 months (vs >80% decline within 24 months in the placebo subgroup <27 years old), resulted in lower HbA1c concentrations and tended to reduce glycaemic variability (p=0.08). No longterm adverse events were observed. A 6 day ChAglyCD3 treatment can suppress the rise in insulin requirements of recent-onset type 1 diabetic patients over 48 months, depending on their age and initial residual beta cell function. In younger patients this effect is associated with reduced deterioration of metabolic variables. These observations help to define inclusion criteria for prevention trials. ClinicalTrials.gov NCT00627146 Center grants from the Juvenile Diabetes Research Foundation (4-2001-434, 4-2005-1327) and grants from the Belgian Fund for Scientific Research-Flanders and from Brussels Free University-VUB.

A Diabetes Outcome Progression Trial (ADOPT): baseline characteristics of Type 2 diabetic patients in North America and Europe

To examine baseline characteristics of patients recruited into ADOPT, a multinational trial comparing three oral glucose-lowering monotherapies. Between April 2000 and June 2002, 4360 patients aged 30-75 years with Type 2 diabetes diagnosed for < 3 years and remaining on diet therapy alone with fasting plasma glucose levels (FPG) between 7.0 and 10.0 mmol/l were enrolled by 488 North American and European centres. Medical histories, anthropometric data and laboratory measurements were determined using common methodologies. The mean (SD) age of the patients was 57 (10) years, body mass index 32.2 (6.4) kg/m(2), HbA(1c) 7.4 (0.9)%; 58% were male, 88% Caucasian and 15% smoked. North American Caucasians (NAC) were younger, more obese, and more insulin resistant than European Caucasians (EUC), but had better pancreatic B-cell function. NAC had lower total, low-density lipoprotein- and high-density liporpotein-cholesterol concentrations with higher triglyceride concentrations and were more often on lipid-lowering treatment. They had lower blood pressure levels but were equally likely to be on antihypertensive treatment. Metabolic syndrome was more frequent and microalbuminuria less frequent in NAC. Within North America, NAC had lower HbA(1c) concentrations than Blacks, Hispanics and Asians despite similar or higher FPG and 30-min postchallenge glucose concentrations. Caucasian North American and European ADOPT patients differ with respect to adiposity, insulin resistance and metabolic syndrome prevalence. North American Blacks, Hispanics and Asians had lower HbA(1c) concentrations than NAC despite similar or higher glucose concentrations. These phenotypic differences may influence the progression of Type 2 diabetes and the response to initial oral glucose-lowering monotherapy.

Reference Intervals for Hemoglobin A1c in Pregnant Women: Data from an Italian Multicenter Study

The reference intervals for hemoglobin A1c (Hb A1c) in pregnant women without diabetes are not well defined, and few examples of reference intervals established by networks of different laboratories are available. Five Italian Diabetic Care Units were involved in the study. Data were collected from 445 pregnant women without diabetes, selected on the basis of glucose challenge test results, and from 384 nonpregnant control women. The Hb A1c measurements were performed with HPLC systems aligned to the Diabetes Control and Complications Trial. Plasma glucose measurements were also performed locally. Both Hb A1c and glucose measurements were harmonized by running appropriate external quality assessment schemes. The reference intervals were calculated in terms of nonparametric 2.5th to 97.5th percentiles with 0.90 confidence intervals. The Hb A1c measurements were reproducible (CV = 2.0%) and accurate [mean (SE) difference from the target values, -0.10 (0.06)%]. Glucose measurements were also reproducible (mean CV = 3.2%) and accurate [difference from the target values, -0.01 (0.04) mmol/L]. To calculate common reference intervals, we merged the data collected in the different centers. The Hb A1c reference intervals were 4.0%-5.5% for pregnant nondiabetic women and 4.8%-6.2% for nonpregnant controls. Healthy pregnant women have lower Hb A1c concentrations than nonpregnant women. The reference intervals for Hb A1c in pregnant women should therefore be lower than those currently in use.

Abnormal haemoglobins, Hb Takamatsu and Hb G-Szuhu, detected during the analysis of glycated haemoglobin (HbA1C) by high performance liquid chromatography

Background—During medical checkups of two unrelated female outpatients during their annual health examination and one male inpatient suffering from cardiac failure the glycated haemoglobin (HbA1C) concentrations measured by high performance...

A Nondiabetic Case of Hemoglobin Variant (Hb Niigata) with Inappropriately High and Low HbA1c Titers Detected by Different Methods

Human adult hemoglobin (Hb) consists of HbA (96% of the total), HbA2 (3%), and HbF (1%). HbA contains a number of subfractions, including HbA1a2, HbA1b, and HbA1c (glycosylated Hb). HbA1c has been used as a clinical marker for blood sugar control for the past one to two months. Inappropriately low or high HbA1c concentrations in comparison with blood glucose concentrations are caused by various conditions of Hb structure and metabolism; under such conditions, the use of HbA1c as a clinical marker cannot be warranted. Abnormally low HbA1c concentrations are usually encountered in patients with high turnover rates of Hb, whereas disproportionately high HbA1c concentrations are found under relatively rare conditions. Various hereditary Hb variants have been reported to cause disproportionately high and low HbA1c titers, as determined by chromatographic methods such as HPLC (1)(2)(3)(4)(5)(6). Recently, another simple and specific method for the quantitation of HbA1c, a latex immunoagglutination (LA) method that uses a monoclonal antibody against a glucose moiety at the β-chain N-terminal, has been developed and used in place of HPLC methods. However, the relevance of the LA method for measurement of HbA1c concentrations in cases with Hb variants has not been tested. We report a case of a Hb variant (Hb Niigata) (7) with inappropriately increased and decreased HbA1c measured with HPLC and LA, respectively. Thus, LA may have a limitation for the accurate quantitation of HbA1c in some special cases. A 58-year-old male (weight, 58.8 kg; height, 162.5 cm) without any abnormal signs or symptoms was evaluated with routine laboratory data at the time of an annual health check provided by his employer. His HbA1c measured with LA was below the reference interval (2.9%), but his fasting blood glucose (FBG) was 5.4 mmol/L (98 …