Prediction the Occurrence of Thalassemia With Hematological Phenotype by Diagnosis of Abnormal HbA1c

BACKGROUND

The current investigation aims to analyze the occurrence of thalassemia in patients who participated in hemoglobin A1c (HbA1c) testing in clinical laboratory showing high hemoglobin F (HbF) level (≥ 1.5%) or abnormal Hb peak and predict the main influence factors by using different statistical models.

METHODS

The current investigation is a single-center retrospective cohort study. HbA1c concentration was detected by using TOSOH HLC-723G8 glycated hemoglobin analyzer. SNaPshot SNP (Single Nucleotide Polymorphism) typing and AccuCopy technology were employed to detect mutations in thalassemia-related pathogenic genes.

RESULTS

A total of 126 patients endured high HbF levels or abnormal Hb peak during HbA1c detection, and 66.7% of subjects (n = 84) showed thalassemia mutations. Three heterozygosity mutations, including c.52A>T (p.K18*), c.-78A>G, and c.126_129delCTTT(p.F42Lfs*19) present in HBB gene, were also identified. --SEA/αα mutation demonstrated the youngest ages (p < 0.001). 17 M (p < 0.001) and 41/42 M (p < 0.01) mutations with β-thalassemia showed higher HbF levels compared with patients without thalassemia mutations. Except for -α3.7, mutations in thalassemia showed lower levels of mean corpuscular hemoglobin (MCH) and mean corpuscular volume (MCV) compared with patients without thalassemia mutations. Patients with thalassemia mutations showed younger age (p < 0.001), lower Hb (p < 0.001), MCV and MCH levels (p < 0.001), higher red blood cell (RBC) count (p < 0.001), and platelet distribution width (PDW) level (p = 0.007) than patients without thalassemia mutations. Three statistical models indicate MCV is the most valuable independent factor for predicting thalassemia and ROC (receiver operating characteristic) curves analysis of AUC (Area Under the Curve) of 0.855 (95% CI [0.787-0.923], p < 0.001) with MCV.

CONCLUSION

High HbF level (≥ 1.5%) or abnormal Hb peak present in HbA1c testing indicated high incident rate of thalassemia. MCV is the most valuable independent predicting factor for subjects having thalassemia.

Dried Blood Spot Test for Glycated Hemoglobin Measurement in Pediatric Diabetes Care

BACKGROUND

The dried blood spot (DBS) card is a novel collection method for measuring glycated hemoglobin (A1C) in individuals with diabetes mellitus. The potential benefits of DBS specimens compared with traditional phlebotomy include a reduction in required total blood volume, reduced procedural pain, and an ability for self-initiated collection. DBS cards for A1C measurement have been validated in the adult population, but there is a paucity of pediatric data.

METHODS

The aim of this study was to validate the use of A1C measurement by DBS cards in comparison to venous A1C and to identify potential barriers to implementing this novel approach. Venous and DBS card A1C samples were collected simultaneously from 62 patients at their local laboratory and transported to the central provincial lab for analysis. Correlation analyses compared venous and DBS A1C with data rescaling performed to account for the DBS-venous interassay difference.

RESULTS

Mean venous A1C was 7.49% and DBS A1C was 7.26%, with an interassay difference of 0.23%. Data showed a strong, positive correlation between A1C collection methods (r=0.86, p<0.001); this was further strengthened at lower A1C values (A1C <7.5%, r=0.87, p<0.0001). A stronger relationship emerged when the data were rescaled to account for the DBS-venous interassay difference (r=0.8935, p<0.0001).

CONCLUSIONS

Given the potential feasibility, practicality, accessibility, cost-effectiveness, and performance characteristics of the DBS A1C, especially at lower A1C values hovering around the diagnostic threshold for diabetes, this study provides supporting evidence for consideration of the use of DBS A1C testing in pediatric diabetes care.

Prevalence of pre-diabetes in adults aged 25 - 45 years in a Durban-based clinical setting, South Africa: A retrospective study

AIM

Due to pre-diabetes being underexplored, its prevalence was investigated in study participants aged 25-45 years in a Durban-based tertiary-level clinical setting in South Africa.

METHODS

The study was done using a retrospective study design. Fasting blood samples from consented patients with no previous diagnosis of diabetes and within the specified age range were collected from King Edward Hospital in Durban. The pre-diabetes diagnosis was confirmed in participants with fasting glucose concentrations between 5.6 and 6.9 mmol/L and glycated haemoglobin (HbA1c) levels between 5.7 % and 6.4 % using the American Diabetes Association (ADA) and World Health Organisation (WHO) diagnosis criteria. The study participants' characterisation was stratified according to the diagnosis criterion, age, gender and ethnicity.

RESULTS

An alarming 68 % average pre-diabetes prevalence across ADA and WHO criteria in the Durban, eThekwini district sample population. The highest prevalence was recorded using the IFG criterion (83%) and the lowest when using the HbA1c criterion (54 %). Between the White, Black and Indian ethnic groups, the Indian group were more predisposed to pre-diabetes onset, with a prevalence of 62.7 %.

CONCLUSION

If pre-diabetes management is unattended, an unprecedented increase in metabolic disorders such as Type 2 Diabetes Mellitus (T2DM) and all-cause mortality incidence can be expected. Therefore, the study reveals a window of opportunity to intensify preventative measures and mitigate the incidence of T2DM.

Comprehensive profiling and kinetic studies of glycated lysine residues in human serum albumin

Lysine residues of proteins slowly react with glucose forming Amadori products. In hyperglycemic conditions, such as diabetes mellitus, this non-enzymatic glycation becomes more pervasive causing severe medical complications. The structure and conformation of a protein predisposes lysine sites to differing reactivity influenced by their steric availability and amino acid microenvironment. The goal of our study was to identify these sites in albumin and measure glycation affinities of lysine residues. We applied a bottom-up approach utilizing a combination of three LC-MS instruments: timsTOF, Orbitrap, and QTRAP. To prove applicability to samples of varying glycemic status, we compared in vitro glycated and non-glycated HSA, as well as diabetic and non-diabetic individual samples. The analysis of lysine glycation affinities based on peptide intensities provide a semi-quantitative approach, as the results depend on the mass spectrometry platform used. We found that glycation levels based on multiple reaction monitoring (MRM) quantitation better reflect individual glycemic status and that the glycation percentage for each site is in linear relation to all other sites. To develop an approach which more accurately reflects glycation affinity, we developed a kinetics model which uses results from stable isotope dilution HPLC-MRM methodology. Through glycation of albumin at different glucose concentrations, we determine the rate constants of glycation for every lysine residue by simultaneous comparative analysis.

Development and Validation of a Simple Risk Model for Predicting Metabolic Syndrome (MetS) in Midlife: A Cohort Study

Purpose

To develop and validate a simple risk model for predicting metabolic syndrome in midlife using a prospective cohort data.

Design

Prospective cohort study.

Participants

A total of 7626 members of the 1958 British birth cohort (individuals born in the first week of March 1958) participated in the biomedical survey at age 45 and have completed information on metabolic syndrome.

Methods

Variables utilised were obtained prospectively at birth, 7, 16, 23 and 45 years. Multivariable logistic regression was used to develop a total of ten (10) MetS risk prediction models taking the life course approach. Measures of discrimination and calibration were used to evaluate the performance of the models. A pragmatic criteria developed was used to select one model with the most potential to be useful. The internal validity (overfitting) of the selected model was assessed using bootstrap technique of Stata.

Main Outcome Measure

Metabolic syndrome was defined based on the NCEP-ATP III clinical criteria.

Results

There is high prevalence of MetS among the cohort members (19.6%), with males having higher risk as compared to females (22.8% vs 16.4%, P < 0.001). Individuals with MetS are more likely to have higher levels of HbA1c and low HDL-cholesterol. Similarly, regarding the individual components of MetS, male cohort members are more likely to have higher levels of glycaemia (HbA1c), BP and serum triglycerides. In contrast, female cohort members have lower levels of HDL-cholesterol and higher levels of waist circumference. Furthermore, a total of ten (10) MetS risk prediction models were developed taking the life course approach. Of these, one model with the most potential to be applied in practical setting was selected. The model has good accuracy (AUROC 0.91 (0.90, 0.92)), is well calibrated (Hosmer-Lemeshow 6.47 (0.595)) and has good internal validity.

Conclusion

Early life factors could be included in a risk model to predict MetS in midlife. The developed model has been shown to be accurate and has good internal validity. Therefore, interventions targeting socioeconomic inequality could help in the wider prevention of MetS. However, the validity of the developed model needs to be further established in an external population.

Life-Course Influence of Adolescent Behaviour Problems on Type 2 Diabetes in Midlife: Results from 1958 British Birth Cohort Study

PURPOSE

To assess whether there is a long-term relationship between childhood behaviour problems and type 2 diabetes in midlife. The study will also investigate whether any of such relationship is independent of other factors which may be associated with type 2 diabetes.

DESIGN

Cohort study.

PARTICIPANTS

A total of 9377 members of the 1958 British birth cohort participated in the biomedical survey at age 45 years. The cohort has been followed up at regular intervals in childhood (age 7, 11 and 16 years) and adulthood (23, 33, 42 and 45 years).

PREDICTOR VARIABLES

Information regarding childhood behaviour collected during follow-ups at ages 7, 11 and 16 years.

MAIN OUTCOME VARIABLES

Type 2 diabetes assessed using HbA1c at age 45 years.

RESULTS

Unadjusted estimates show that teachers reported adolescent behaviour problems at age of 16 are associated with increased risk of type 2 diabetes in midlife. After adjustment for potential confounders and mediators in childhood and adulthood, a relationship was observed between the severity of adolescent behaviour problems and type 2 diabetes risk in midlife (mild behaviour problems: OR 2.17, 95% CI 1.11-4.23; severe behaviour problems: OR 4.40, 95% CI 1.14-16.99). However, no such relationship was observed between behaviour problems at 7 and 11 years and type 2 diabetes in midlife.

CONCLUSION

There is an association between adolescent behaviour problems and an increased risk of type 2 diabetes in midlife. Further molecular/genetic studies are required to understand the biological basis for this observed association.

Erythrocytosis and Performance of HbA1c in Detecting Diabetes on an Oxygen-Deficient Plateau: A Population-based Study

CONTEXT

The hemoglobin A1c (HbA1c) test is a standard test for diabetes screening and diagnosis.

OBJECTIVE

To evaluate A1c performance for diabetes screening in high-altitude polycythemia compared to a population with a high proportion of people living in an oxygen-deficient environment.

DESIGN

A population-based epidemiological survey was conducted.

SETTING

The cities Lhasa and Shigatse were selected. Volunteers were recruited through educational advertisements about diabetes.

PARTICIPANTS

A total of 1401 Tibetan adults without known diabetes.

INTERVENTIONS

Oral glucose tolerance test (OGTT), HbA1c, and complete blood cell count were performed. Hemoglobin A1c was evaluated using high-performance liquid chromatography, and serum glucose level, using the hexokinase method.

MAIN OUTCOME MEASURES

World Health Organization criteria were used to define diabetes and prediabetes. Hemoglobin A1c test performance was evaluated using receiver operating characteristic analysis.

RESULTS

The participants' mean age was 44.3 ± 15.0 years; 33.3% of the participants were men and 38.6% lived in urban areas. The prediabetes and diabetes prevalence rates were 7.5% and 3.6%, respectively. The optimal HbA1c cutoff for detecting diabetes was 46 mmol/mol (6.4%), with a sensitivity and specificity of 60.8% and 93.6%, respectively. The cutoff for detecting diabetes was 6.7% (50 mmol/mol) in subjects with high-altitude polycythemia (HAPC). The relationship between red blood cell (RBC) counts and HbA1c was significant (P < 0.001), while there was no correlation between hemoglobin (Hb) and HbA1c (P = 0.085). Multiple linear regression analysis showed that after adjusting for age and fasting serum glucose or 2-hour OGTT (OGTT2h) serum glucose, RBC count and not Hb level was an independent risk factor for HbA1c (β = 0.140, P < 0.001).

CONCLUSIONS

The optimal HbA1c cutoff for detecting diabetes was 46 mmol/mol (6.4%) in Tibet. Red blood cell count was an independent risk factor for elevated HbA1c, and HAPC may affect the predictive ability of HbA1c.

Association Between Glycaemic Control and the Intake of Thiazide Diuretics, Beta Blockers and Levothyroxine in People Without Diabetes

OBJECTIVE

The pharmacological additional information for many medications includes warnings stating that the blood sugar control may be worsened by the intake of certain drugs. However a quantification of the effects is missing. This may result in confusion for patients as well as for their physicians. The aim of this study was to assess a potential association between medication (beta blockers, thiazides, levothyroxine) and HbA_1c in people without diabetes.

METHODS

In this cross-sectional study we analysed data from 2 921 people (7 699 visits) without diabetes (age 46.6 y; 69.1% women; BMI 27.6±6.4 kg/m²; HbA_1c 5.2%) who had at least one HbA_1c determination and a complete documentation of their drug intake. An oral glucose tolerance test was not performed. The participants were divided in 8 groups (no regular drug intake, levothyroxine alone, beta blockers alone, thiazides alone, combination 2 of 3, combination of all 3). Patients with known distorting influences of the HbA_1c were excluded.

RESULTS

People with no regular drug intake had an HbA_1c of 5.4% [35.8 mmol/mol]. The HbA_1c of the group that took all 3 drugs in combination was 5.6% [38.2 mmol/mol]. A multiple linear mixed model showed an increase in HbA_1c for thiazides (β=0.0558, p=0.025) and a decrease for combination of levothyroxine and thiazide (β=-0.0765, p=0.010).

CONCLUSION

Thiazides and the combination of levothyroxine and thiazides were associated with slight changes in HbA_1c. In this study there was no association between the intake of beta blockers and HbA_1c. At least for people without diabetes these effects seem to be of minor importance.

Diabetes care in the dispersed population of Greenland. A new model based on continued monitoring, analysis and adjustment of initiatives taken

Diabetes used to be a rare condition among Inuit in Greenland. However, research in recent decades has shown a high prevalence of undiagnosed diabetes. Addressing diabetes in the geographically dispersed population of Greenland presents a challenge to the health care system. In 2008, a new model of diabetes care was introduced in Greenland that included continual monitoring, analysis, and adjustment of initiatives taken. The overall aim of this review was to review the feasibility of the monitoring of an ongoing national diabetes care programme. After ten years of observation it was clear that monitoring of such a programme based on information in electronic medical records in Greenland was feasible. It was found that the majority of the population in Greenland was in contact with the health care system. Increased diagnostic activity resulted in an increased prevalence of diagnosed diabetes. The quality of diabetes care in Greenland and the testing effectiveness of gestational diabetes were improved. Microvascular complications were frequently observed among Greenlandic diabetic patients, except for retinopathy that was as an exception. In summary, this model may improve diabetes care and potentially care for other chronic conditions in Greenland, and may also be helpful in other remote settings where chronic disease care is difficult.Abbreviations: AD: Anno Domini; ADA: American Diabetes Association; BC: Before Christ; BMI: Body Mass Index; BP: Blood Pressure; CWB: Capillary Whole Blood; EMR: Electronic Medical Record; EASD: European Association for Study of Diabetes; GA: Gestational Age; GDM: Gestational Diabetes Mellitus; FIGO: The International Federation of Gynaecology and Obstetrics; HbA1c: Glycosylated haemoglobin; IDF: International Diabetes Federation; LDL: Low density lipoprotein; NDQIA: National Diabetes Quality Improvement Alliancel; NICE: National Institute for Health and Care Excellence; OECD: Organisation for Economic Co-operation and Development; OGTT: Oral Glucose Tolerance Test; QIH: Queen Ingrid Hospital; RCT: Randomised Controlled Tria;l T1D: Type 1 Diabetes; T2D: Type 2 Diabetes; UACR: Urine Albumin Creatinine Ratio; WHO: World Health Organisation.

Risk of Cardiovascular Disease and Death in Individuals With Prediabetes Defined by Different Criteria: The Whitehall II Study

OBJECTIVE

We compared the risk of cardiovascular disease (CVD) and all-cause mortality in subgroups of prediabetes defined by fasting plasma glucose (FPG), 2-h plasma glucose (2hPG), or HbA1c.

RESEARCH DESIGN AND METHODS

In the Whitehall II cohort, 5,427 participants aged 50-79 years and without diabetes were followed for a median of 11.5 years. A total of 628 (11.6%) had prediabetes by the World Health Organization (WHO)/International Expert Committee (IEC) criteria (FPG 6.1-6.9 mmol/L and/or HbA1c 6.0-6.4%), and 1,996 (36.8%) by the American Diabetes Association (ADA) criteria (FPG 5.6-6.9 mmol/L and/or HbA1c 5.7-6.4%). In a subset of 4,730 individuals with additional measures of 2hPG, 663 (14.0%) had prediabetes by 2hPG. Incidence rates of a major event (nonfatal/fatal CVD or all-cause mortality) were compared for different definitions of prediabetes, with adjustment for relevant confounders.

RESULTS

Compared with that for normoglycemia, incidence rate in the context of prediabetes was 54% higher with the WHO/IEC definition and 37% higher with the ADA definition (P < 0.001) but declining to 17% and 12% after confounder adjustment (P ≥ 0.111). Prediabetes by HbA1c was associated with a doubling in incidence rate for both the IEC and ADA criteria. However, upon adjustment, excess risk was reduced to 13% and 17% (P ≥ 0.055), respectively. Prediabetes by FPG or 2hPG was not associated with an excess risk in the adjusted analysis.

CONCLUSIONS

Prediabetes defined by HbA1c was associated with a worse prognosis than prediabetes defined by FPG or 2hPG. However, the excess risk among individuals with prediabetes is mainly explained by the clustering of other cardiometabolic risk factors associated with hyperglycemia.

Nondiabetic Glucometabolic Status and Progression of Aortic Stiffness: The Whitehall II Study

OBJECTIVE

Aortic stiffness is an important predictor of future morbidity and mortality. Diabetes is associated with increased aortic stiffness, but the importance of nondiabetic glucometabolic status for accelerated aortic stiffening is unclear. We tested the hypothesis that adverse glucometabolic status is associated with accelerated aortic stiffening in individuals without diabetes, independently of known risk factors for arterial stiffening.

RESEARCH DESIGN AND METHODS

Glucometabolic status and other cardiovascular risk factors were assessed at baseline in 2008-09, and carotid femoral pulse wave velocity (cfPWV) at baseline and follow-up in 2012-13, in 4,386 participants without diabetes of the Whitehall II Study.

RESULTS

The mean age of the cohort at cfPWV baseline was 60 years, and 74% were male. cfPWV increased from (mean ± SE) 8.30 ± 0.03 to 8.98 ± 0.04 m/s during 4 years of follow-up. At baseline, cfPWV was associated with fasting and 2-h postload glucose, HbA_1c, and HOMA-insulin resistance (HOMA-IR). HbA_1c and HOMA-IR were associated with progression of cfPWV after adjusting for physiological confounders and cardiovascular risk factors. A 1 SD higher HbA_1c and HOMA-IR were associated with greater increases in cfPWV (0.11 m/s per 5 years [95% CI 0.04, 0.18], P = 0.003 and 0.09 m/s per 5 years [0.01, 0.17], P = 0.03, respectively). Additional adjustment for BMI weakened the association with HOMA-IR but not with HbA_1c.

CONCLUSIONS

HbA_1c is independently associated with accelerated progression of aortic stiffness in individuals without diabetes. These findings suggest that long-term glucometabolic status, even in individuals without diabetes, could be an important target for preventative strategies against vascular aging.

A comparative evaluation of the analytical performances of Capillarys 2 Flex Piercing, Tosoh HLC-723 G8, Premier Hb9210, and Roche Cobas c501 Tina-quant Gen 2 analyzers for HbA1c determination

INTRODUCTION

Haemoglobin A_1c (HbA_1c) is widely used in the management of diabetes. Therefore, the reliability and comparability among different analytical methods for its detection have become very important.

MATERIALS AND METHODS

A comparative evaluation of the analytical performances (precision, linearity, accuracy, method comparison, and interferences including bilirubin, triglyceride, cholesterol, labile HbA_1c (LA_1c), vitamin C, aspirin, fetal haemoglobin (HbF), and haemoglobin E (Hb E)) were performed on Capillarys 2 Flex Piercing (Capillarys 2FP) (Sebia, France), Tosoh HLC-723 G8 (Tosoh G8) (Tosoh, Japan), Premier Hb9210 (Trinity Biotech, Ireland) and Roche Cobas c501 (Roche c501) (Roche Diagnostics, Germany).

RESULTS

A good precision was shown at both low and high HbA_1c levels on all four systems, with all individual CVs below 2% (IFCC units) or 1.5% (NGSP units). Linearity analysis for each analyzer had achieved a good correlation coefficient (R² > 0.99) over the entire range tested. The analytical bias of the four systems against the IFCC targets was less than ± 6% (NGSP units), indicating a good accuracy. Method comparison showed a great correlation and agreement between methods. Very high levels of triglycerides and cholesterol (≥ 15.28 and ≥ 8.72 mmol/L, respectively) led to falsely low HbA_1c concentrations on Roche c501. Elevated HbF induced false HbA_1c detection on Capillarys 2FP (> 10%), Tosoh G8 (> 30%), Premier Hb9210 (> 15%), and Roche c501 (> 5%). On Tosoh G8, HbE induced an extra peak on chromatogram, and significantly lower results were reported.

CONCLUSIONS

The four HbA_1c methods commonly used with commercial analyzers showed a good reliability and comparability, although some interference may falsely alter the result.

Analytical verification and quality assessment of the Tosoh HLC-723GX HbA1c analyzer

Objectives

Ion-exchange high-performance liquid chromatography (IE-HPLC) has long been used as a reproducible and versatile analytical tool for HbA_1c measurement.

In this study, we performed analytical verification and quality assessment of the recently introduced small IE-HPLC Tosoh HLC-723GX HbA_1c analyzer, and a comparison of results to immunoassay (IA) and capillary electrophoresis (CE).

Design and methods

The total imprecision of Tosoh HLC-723GX was verified according to CLSI EP15-A2 protocol using commercial control materials (C-QC) and pooled human whole blood samples (HWB). The Sigma metric was used for the evaluation of quality targets. HbA_1c results were compared to automated CE (MiniCap Flex Piercing, Sebia, France) and IA (Tina-quant HbA_1c Gen 2, Cobas Integra 400+, Roche Diagnostics, USA) procedures.

Results

The total imprecision of Tosoh HLC-723GX-HbA_1c for IFCC(mmol/mol) and NGSP(%) units was: 1.91/1.25% (HbA_1c=31 mmol/mol/5.0%) and 0.51/0.63% (HbA_1c=84 mmol/mol/9.8%) for C-QC, and 0.39/0.2% (HbA_1c=47 mmol/mol/6.5%) and 0.77/0.46% (HbA_1c=94 mmol/mol/10.8%) in HWB samples, respectively. Bland-Altman analysis did not reveal any deviation of the results between Tosoh HLC-723GX and CE: mean difference 0.0% (95%CI: −0.02927 to 0.02653%), while the mean HbA_1c difference against IA was −0.07% (95%CI: −0.1039 to −0.02765). At the selected HbA_1c clinical decision level (48 mmol/mol/6,5%), six sigma analysis gave σ value of 3.91, within a desirable classification of performance.

Conclusion

The analytical performance of the Tosoh HLC-723GX complies with the rigorous quality criteria for clinical use of HbA_1c, with the results comparable to the CE procedure. Tosoh HLC-723GX provides a plausible analytical choice for reliable HbA_1c measurement in low-volume laboratories.

•

Compliance to the rigorous quality targets is necessary for the reliable clinical use of HbA_1c.

•

A small, fully automated benchtop HbA_1c analyzer (Tosoh HLC-723GX) was evaluated.

•

Tosoh HLC-723GX anaylzer met the six sigma-based quality targets.

•

Low-volume laboratories could provide clinically reliable HbA1c results by the Tosoh HLC-723GX analyzer.

Evaluation of the Sebia Capillarys 3 Tera and the Bio-Rad D-100 Systems for the Measurement of Hemoglobin A1c

OBJECTIVES

We evaluated the Bio-Rad (Irvine, CA) D-100 and the Sebia (Lisses, France) Capillarys 3 Tera for the measurement of hemoglobin A1c (HbA1c) in venous blood samples.

METHODS

Whole-blood samples and control material were analyzed with the D-100 and Capillarys 3 Tera and compared with our routine method, HLC-723G7 (Tosoh, Tokyo, Japan). An evaluation protocol to test precision, trueness, linearity, carryover, and selectivity was set up according to Clinical and Laboratory Standards Institute guidelines. The results were presented in National Glycohemoglobin Standardization Program and International Federation of Clinical Chemistry (IFCC) units.

RESULTS

Both systems showed excellent precision (total coefficients of variation <2%, IFCC) and bias (<0.3% or 3 mmol/mol). Linearity was demonstrated for HbA1c values from 3.8% (18 mmol/mol) to 18.5% (179 mmol/mol). Results were correlated with the routine method using Bland-Altman analysis, showing a mean difference of 0.33% or 3.6 mmol/mol for the D-100 and of 0.25% or 2.6 mmol/mol for the Capillarys 3 Tera vs HLC-723G7. None of the automated instruments were prone to interferences by labile HbA1c (≤10 g/L glucose), carbamylated hemoglobin (≤0.5 mmol/L potassium cyanate), hemoglobin variants, bilirubin (≤15 mg/dL), and triglycerides (≤3,360 mg/dL).

CONCLUSIONS

The Bio-Rad D-100 and the Sebia Capillarys 3 Tera instruments performed well for the determination of HbA1c in terms of quality criteria as well as for sample throughput.

Quality of HbA1c Measurement in the Practice: The German Perspective

Hemoglobin A1c (HbA1c) measurement has come to be a cornerstone in modern diabetes therapy. However, the methodological aspects of this type of measurement have been given little attention lately due to its position as an established method of choice. Nevertheless, quite a number of issues face practical application, such as clinically relevant differences between different measurement methods--both lab-based and point-of-care (POCT) systems will show better or worse diabetes management results after switching methods; and there are a number of possible reasons that need to be known and observed in practice. The aim of this review is to draw attention to these problems from a German point of view and provide suggestions for appropriate measures to improve the situation.

Glycated Serum Albumin and AGE Receptors

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

Evaluation of the Sebia CAPILLARYS 2 flex piercing for the measurement of HbA(1c) on venous and capillary blood samples

OBJECTIVES

We evaluated the Sebia CAPILLARYS 2 Flex Piercing (Cap 2FP; Sebia, Lisses, France) for measurement of hemoglobin A1c (HbA1c) on venous and capillary blood samples.

METHODS

We analyzed whole-blood samples and control materials with the Cap 2FP and Tosoh G8 (Tosoh Corporation, Tokyo, Japan). Capillary blood samples were analyzed on the Cap 2FP on different storage conditions and were compared with venous samples.

RESULTS

Both instruments achieved total imprecision of less than 2.5% (International Federation of Clinical Chemistry units). Bias was 1 mmol/mol or less and 4 mmol/mol or less for the Cap 2FP and Tosoh G8, respectively. The Cap 2FP was not prone to common interferences. The Tosoh G8 showed significant bias only for carbamylated hemoglobin and did not completely separate hemoglobin D and hemoglobin E. On the Cap 2FP, storage of capillary blood at room temperature showed no significant bias. There was good agreement with venous blood.

CONCLUSIONS

The Cap 2FP and Tosoh G8 perform excellently for HbA1c determination. Capillary blood can be analyzed on the Cap 2FP as an acceptable alternative to venous blood and point-of-care testing. Home collection and central analysis of capillary blood could contribute to a reduction of health care costs without reducing quality of HbA1c determination.

Evaluation of enzymatic BM Test HbA1c on the JCA-BM6010/C and comparison with Bio-Rad Variant II Turbo, Tosoh HLC 723 G8, and AutoLab immunoturbidimetry assay

BACKGROUND

A novel enzymatic HbA1c assay was introduced for use in an automated chemistry analyzer. With this unique method, HbA1c and plasma glucose can be measured from the same EDTA tube. We evaluated the analytical performance of this enzymatic HbA1c assay in a JCA-BM6010/C analyzer and compared the HbA1c values with the results from other widely used methodological instruments.

METHODS

The imprecision, linearity, carry-over and concordance rate of the enzymatic HbA1c test (BM Test HbA1c) using the JCA-BM6010/C analyzer were evaluated. Three hundred and seventy-seven specimens with HbA1c concentrations from 16 to 133 mmol/mol were used for a comparison study with two high performance liquid chromatography methods: Variant II Turbo and Tosoh HLC 723 G8 and the AutoLab Hemoglobin A1c immunoturbidimetry reagent using a Hitachi 7600-110. Forty specimens were used for the glucose method comparison.

RESULTS

The HbA1c coefficients of variation of the within-run imprecision for low and high levels were 0.6% and 0.4%, respectively. The linearity of the BM Test HbA1c using the JCA-BM6010/C analyzer was excellent in the range between 31 mmol/mol and 143 mmol/mol. The carry-over rate was 0.2%. The relationships between the BM test and the other three methods were 0.916×Tosoh G8+3.644, r=0.986; 0.887×Bio-Rad Variant II+1.896, r=0.972; and 0.941×AutoLab+4.532, r=0.977. The concordance rates using a cut-off of 48 mmol/mol were 91.5% with Tosoh G8, 82.8% with Bio-Rad Variant II, and 91.0% with AutoLab. The simultaneously assayed plasma glucose with HbA1c was 1.002×Routine plasma glucose+0.625, r=1.000 CONCLUSIONS: The enzymatic BM Test HbA1c in the JCA-BM6010/C analyzer showed excellent precision and linearity, and a minimal carry-over rate. The simultaneously assayed plasma glucose analysis showed good performance.

A history of HbA1c through Clinical Chemistry and Laboratory Medicine

HbA(1c) was discovered in the late 1960s and its use as marker of glycemic control has gradually increased over the course of the last four decades. Recognized as the gold standard of diabetic survey, this parameter was successfully implemented in clinical practice in the 1970s and 1980s and internationally standardized in the 1990s and 2000s. The use of standardized and well-controlled methods, with well-defined performance criteria, has recently opened new directions for HbA(1c) use in patient care, e.g., for diabetes diagnosis. Many reports devoted to HbA1c have been published in Clinical Chemistry and Laboratory Medicine (CCLM) journal. This review reminds the major steps of HbA(1c) history, with a special emphasis on the contribution of CCLM in this field.

Comparison of Arkray/ELITech ADAMS HA-8180V with Bio-Rad Variant, II Turbo2.0 and Tosoh Bioscience HLC-723G8 for HbA1c determination

OBJECTIVE

This study aimed to evaluate a new ion-exchange HPLC system to measure hemoglobin A1c (HbA1c) in comparison to two other widely used HPLC systems.

METHODS

Analytical performance and hemoglobin variants detection was assessed on the new Arkray/ELITech ADAMS HA-8180V, in parallel to Bio-Rad Variant II Turbo2.0 and Tosoh Bioscience HLC-723G8. A method comparison and concordance for the classification of patients according to the American Diabetes Association (ADA) categories was performed using kappa test.

RESULTS

ADAMS HA-8180V demonstrated excellent within-run imprecision (0%) and between-run imprecision: ≤1.21% using blood sample and ≤0.94% using quality controls. Method comparison of ADAMS HA-8180V with the two other systems yielded very high coefficient correlation (r > 0.995). A very good agreement (kappa value ≥0.81) was observed between methods for the classification of patients according to the ADA categories. In addition, all systems were able to detect the presence of most classical variants such as HbC, HbS, HbD, and HbE.

CONCLUSION

The Arkray/ELITech ADAMS HA-8180V demonstrated high analytical performance similar to previous systems such as Biorad(TM) Variant II Turbo 2.0 and Tosoh Bioscience HLC-723G8. The three systems allow a high-quality HbA1c measurement and appeared interchangeable for diabetes diagnosis or for the therapeutic monitoring of patients without hemoglobin variants.

Study of a newly developed high-performance liquid chromatography analyser for glycosylated haemoglobin measurements in blood containing haemoglobin variants in the Japanese population

Background

This study examined the new high-performance liquid chromatography analyser HLC-723GX (GX) and investigated its ability to both measure glycosylated haemoglobin (HbA1c) values and determine whether haemoglobin variants could cause interference with these measurements in the Japanese population.

Methods

For the basic GX examination, the within- and between-run precision, linearity of measurements, correlation of HbA1c values with current systems and the interference of chemically modified haemoglobin were determined. GX interference caused by the haemoglobin variant was examined by analysing 39 clinical laboratory samples that contained haemoglobin variants.

Results

Good within- and between-run precision were found, with the coefficients of variation at ≤1.0%. A wide range of HbA1c measurement values were confirmed, with the HbA1c values strongly correlated with the results of the currently used HLC-723G8 system. Chemically modified haemoglobins were prepared by adding glucose, sodium cyanate, acetaldehyde or acetylsalicylic acid to normal blood samples. None of these samples had any influence on the HbA1c values determined by GX. GX analysis showed haemoglobin variants that eluted after HbA0 and were similar to HbD, or HbS had HbA1c values that were close to those measured by boronate affinity chromatography and immunoassay. GX found lower HbA1c values in blood that contained HbE or haemoglobin variants, which elute before or at nearly the same time as HbA0.

Conclusions

GX is useful for the analysis of HbA1c samples that contain HbD, HbS, HbC and haemoglobin variants, even though the elution times are similar. However, a countermeasure is needed in order to avoid overlooking other haemoglobin variants in Japan.

Diagnosing Diabetes Mellitus: Performance of Hemoglobin A1c Point-of-Care Instruments in General Practice Offices

BACKGROUND

Hemoglobin A1c (Hb A1c) measurement by hospital laboratory instruments, but not by point-of-care (POC) instruments, has been recommended for use to diagnose diabetes mellitus. We evaluated results from 13 Hb A1c external quality assurance (EQA) surveys over a 6-year period in Norway, from both POC instruments used in general practice (GP) offices and instruments in hospital laboratories, against the analytical quality specifications recommended for use of Hb A1c to diagnose diabetes mellitus.

METHODS

All GP offices (n = 1288) and hospital laboratories (n = 52) measuring Hb A1c in Norway participated in the EQA survey. The percentage of participants that performed measurements within the quality specifications was calculated. Pooled within-laboratory CVs were estimated for the Afinion, DCA 2000, DCA 2000+, DCA VantageTM, and Nycocard Hb A1c Reader instruments and for hospital laboratory instruments.

RESULTS

Between 60% to 90% of Afinion and DCA users and hospital laboratories performed Hb A1c measurements within the quality specifications for both trueness (6.0%) and imprecision (CV ≤2.0%) at 2 levels in each EQA survey. The pooled within-laboratory CVs for the Afinion and DCA instruments and hospital laboratories were below the recommended limit of 2.0% for most of the surveys.

CONCLUSIONS

A large proportion of GP offices using Afinion and DCA POC instruments to measure Hb A1c fulfill the analytical quality specifications for diagnosing diabetes mellitus, and these instruments demonstrate analytical quality comparable to that of hospital laboratory instruments. When GP offices participate in a stringent quality assurance program and generate Hb A1c measurements that meet analytical quality specifications, these measurements can be recommended for use to diagnose diabetes mellitus.

Calculation of HbA1c and glycated albumin from serially measured self-monitored blood glucose in patients with type 1 diabetes mellitus

BACKGROUND

Both HbA1c and glycated albumin (GA) values are influenced by weighted mean of preceding blood glucose levels depending on each half-life. Based on this principle, we developed formulas for calculation of HbA1c and GA using data from self-monitored blood glucose (SMBG). We also calculated HbA1c and GA in diabetic patients using the developed formulas.

METHODS

This study included 9 patients with childhood-onset type 1 diabetes mellitus (6 males and 3 females; aged 11.4±4.2 y). From the weekly mean blood glucose (MBG) values obtained by the SMBG data during the previous 20 weeks, we calculated HbA1c and GA using the developed formulas and compared the calculated values with the measured values (n=42).

RESULTS

The measured and the calculated values of HbA1c were 8.5±0.9% and 8.3±1.2%, respectively. The measured and the calculated values of GA were 24.9±3.7% and 26.4±4.0%, respectively. There were strong positive correlations between both values of HbA1c and GA (P<0.0001).

CONCLUSIONS

The calculated HbA1c and GA values using the developed formulas from the SMBG data were generally in agreement with the measured values. Using the calculation formulas, the values of HbA1c and GA could be estimated from serially measured SMBG data.

Effects of miglitol versus sitagliptin on postprandial glucose and lipoprotein metabolism in patients with type 2 diabetes mellitus

Postprandial hyperglycemia and/or hyperlipidemia can contribute to development of atherosclerosis in patients with type 2 diabetes mellitus (T2DM). The objective of this study was to compare the effects of miglitol and sitagliptin on postprandial glucose and lipid metabolism in patients with T2DM. Thirty-five patients with T2DM were randomized to 2 groups receiving miglitol (150 mg/day) or sitagliptin (50 mg/day). Serum variables related to glucose and lipid metabolism were measured before and after treatment for 10 weeks and at 0, 60, and 120 min using a cookie-loading test (CLT). After 10 weeks of treatment, miglitol (n = 16) and sitagliptin (n = 18) caused a similarly significant decrease in hemoglobin A1c (mean: 7.6% to 7.3% versus 8.0% to 7.6%) and a significant increase in fasting insulin levels, with a greater increase observed in the miglitol group than in the sitagliptin group (p=0.03). In addition, a significant decrease in the change in glucose levels after the CLT was observed in both groups, with a greater decrease observed in the miglitol group than in the sitagliptin group (p=0.02). The miglitol group also showed a greater decrease in the change in insulin levels after the CLT than the sitagliptin group (p<0.01). The lipid and lipoprotein levels did not show any significant differences between the groups after the CLT. Our results suggested that miglitol and sitagliptin treatment resulted in similar glycemic control but that a greater decrease in postprandial glucose and insulin levels was observed with miglitol compared with sitagliptin in patients with T2DM.

Incidental findings of variant hemoglobin during hemoglobin A(1c) testing

A variant hemoglobin fraction may be an incidental finding during HbA(1c) analysis using the G8 Tosoh HPLC analyzer, but it is unclear if the retention times and fraction patterns can reliably predict the findings of a high-performance liquid chromatography (HPLC) β-thalassemia program (Bio Rad Variant II analyzer). We chose 100 samples sent for HbA(1c) determinations (G8 Tosoh) with an incidental finding of variant hemoglobin and did a reflex test using the Bio Rad Variant II analyzer (β-thalassemia program). Two observers attempted to predict the results with that analyzer from fraction patterns and retention times of the hemoglobin variants detected with the G8. They independently identified all hemoglobin variants (HbS, Hb Setif, HbC, and HbD) by their patterns and retention times. We conclude that HPLC confirmation of certain variant hemoglobin fractions found incidentally during HbA(1c) testing on the G8 Tosoh is not necessary.

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

AIMS/HYPOTHESIS

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

METHODS

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

RESULTS

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

CONCLUSIONS/INTERPRETATION

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

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

OBJECTIVE

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

STUDY DESIGN

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

RESULT

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

CONCLUSION

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

Changes in glycosylated hemoglobin after initiation of hydroxychloroquine or methotrexate treatment in diabetes patients with rheumatic diseases

OBJECTIVE

Prior research demonstrates that hydroxychloroquine (HCQ) lowers glycosylated hemoglobin (HbA(1c) ) in diabetes patients without rheumatic disease. We examined medical records of patients with diabetes mellitus (DM) and concomitant rheumatic illness to measure changes in HbA(1c) after starting HCQ or methotrexate (MTX).

METHODS

We used electronic medical records to identify patients beginning treatment with either HCQ or MTX who had a diagnosis of DM (or a pretreatment HbA(1c) value of ≥7%) and at least 1 HbA(1c) measurement both before and within 12 months after initiation of treatment. Using a structured medical record abstraction, we examined rheumatic disease diagnosis, cumulative steroid use, duration (months) between drug initiation and lowest HbA(1c) value, a change in DM medication, body mass index (BMI), age, and sex. Adjusted linear regression models determined changes in HbA(1c) from pretreatment values to the lowest posttreatment values within 12 months.

RESULTS

We identified 45 patients taking HCQ and 37 patients taking MTX who met the inclusion criteria. Rheumatoid arthritis had been diagnosed in approximately half of the patients in each group. Age, sex, and mean pretreatment HbA(1c) levels were similar across groups. The mean BMI of those taking HCQ (35.4 kg/m(2) ) was slightly higher than that of those taking MTX (32.2 kg/m(2) ) (P = 0.13). Glucocorticoid use appeared more common in those taking MTX (46%) than in those taking HCQ (29%) (P = 0.17). The mean reduction in HbA(1c) from pretreatment values to the lowest posttreatment values was 0.66% (95% confidence interval [95% CI] 0.26, 1.05) in those taking HCQ compared with 0.11% (95% CI -0.18, 0.40) in those taking MTX. In fully adjusted analyses, the reduction in HbA(1c) among those taking HCQ was 0.54% greater than the reduction among those taking MTX (P = 0.041).

CONCLUSION

HCQ initiation was associated with a significantly greater reduction in HbA(1c) as compared with MTX initiation among diabetes patients with rheumatic disease.