Comparative evaluation of three different methods for HbA1c measurement with High-performance liquid chromatography in diabetic patients

Establishment of reference interval for hemoglobin A1C and other hemoglobin subfractions for healthy Saudi adults

BACKGROUND

The establishment of Reference Intervals (RIs) for Hemoglobin A1C and other hemoglobin subfractions (A1A, A1B, F, LA1C, A0) is of utmost importance in screening, diagnosing, and monitoring diabetes and other hemoglobin abnormalities through the application of high-pressure liquid chromatography (HPLC) technique. Because there are no locally established RIs for these parameters, it is essential to establish RIs specific to the Saudi population to accurately diagnose and monitor diabetic individuals and identify abnormal levels in hemoglobin subfractions.

METHODS

As part of the IFCC global multicenter study of laboratory reference values, a cross-sectional study was conducted in Saudi Arabia. The study involved recruiting a total of 381 healthy adult subjects (>18 years, BMI 28.3 ± 6 kg/m2). Blood samples were analyzed for A1C, biochemical and other immunoassay parameters. The need for RIs based on sex, age, and BMI was determined using the standard deviation ratio (SDR) through a 3-level nested ANOVA.

RESULTS

Based on the threshold of SDR≥0.4, RIs for A1C and other Hb subfractions were not partitioned by sex or BMI, but partitioned by age (<45 & ≥45 years) for A1C, LA1C, A0 and F. Spearman's correlation between glucose, insulin, and C-peptide showed a positive association with different hemoglobin subtractions of A1B, F, A1C, and LA1C. The RIs were obtained by using the parametric method and the latent abnormal values exclusion (LAVE) principle was applied on A1C.

CONCLUSION

This study established RIs for A1C and other Hb subfractions for healthy adult Saudis. Age was found to be an important source of variation for most of the parameters including A1C. These findings will enhance the understanding and clinical decision-making concerning A1C and other hemoglobin subfractions. The elevated upper limit of RIs for A1C reflects the high prevalence of diabetes in the Saudi population specially in those with increased age.

Clinical Risk Assessment and Comparison of Bias between Laboratory Methods for Estimation of HbA1c for Glycated Hemoglobin in Hyperglycemic Patients

INTRODUCTION

Hemoglobin A1c (HbA1c), also known as glycated hemoglobin, is a blood test used to evaluate and track a patient's blood sugar levels over the previous 2-3 months. We have compared the analytical performance of the D10 hemoglobin (HPLC) testing system to that of the immunoturbidimetric technique, which is a light-scattering immunoassay.

OBJECTIVES

To assess the clinical risk assessment between two methods (Compare the two Immunoturbidometric methods (AU680) vs. HPLC method (D10)) in hyperglycemic patients and assess the acceptability of the respective methods in the Clinical biochemistry laboratory.

METHODS

The charge of the globins in Hb was used as the basis for the HPLC method used to measure HbA1c. HPLC detects and quantifies even the tiniest Hb fractions and the full spectrum of Hb variants. HbA1c was measured using the immunoturbidimetric (AU 680 Beckmann coulter analyzer) and high-performance liquid chromatography (HPLC) techniques. Experiments also made use of immunoturbidimetric techniques (using an AU 680 Beckmann coulter analyzer equipment).

RESULTS

There is no statistically significant difference in HbA1c readings between male and female patients, as measured by either the Immunoturbidimetric or HPLC techniques.

CONCLUSION

The immunoturbidimetric and high-performance liquid chromatography techniques for estimating HbA1c yielded identical results. From the results of this study, we may deduce that both techniques are valid for estimating HbA1c. As a result, it may be suggested that both approaches can be used to estimate HbA1c in diabetic individuals.

Comparison of high performance liquid chromatography and turbidimetric inhibition immunoassay methods for measurement of hemoglobin A1c

Aim: Hemoglobin A1c is a valuable parameter for the diagnosis and follow-up of its diabetes mellitus since its biological variation is low, does not require preparation before the test, is not affected by acute stress, and has high preanalytical stability. HbA1c measurement by HPLC has been determined as the reference method by National Glycohemoglobin Standardization Program (NGSP) in USA; after that The International Federation of Clinical Chemistry (IFCC) defined another reference method which could be related with NGSP. In our study, we aim to compare the two NGSP-certified methods of HbA1c, which are high-performance liquid chromatography (HPLC) and turbidimetric inhibition immunoassay (TINIA). Material and Method: HbA1c levels of the patients were measured using two HPLC and one TINIA method in three different hospitals (Lab A, Lab B (Both are HPLC), and Lab C (TINIA), in which Lab A was served as a reference). Because of the lower precision values of LabB, we firstly conducted a method comparison study of 40 volunteers (Group 1). After that, corrective and preventive activities carried out and the precision values in LabB reached the desired range. Following this, another method comparison study consisting of 60 new volunteers (Group 2) was conducted. The statistical flow of this study complied with Clinical Laboratory Standards Institute (CLSI) EP09-A3; Precision studies, Blant-Altman and Passing Bablok regression analysis were performed. Results: The percentage of the mean difference between the two HPLC methods (LabA and LabB) was 3.1%. After corrective and preventive actions had been taken, the mean difference between the two HPLC methods decreased to 2.0%. A decrease in systematic bias was found in our study. Two HPLC methods can be used interchangeably in both Group 1 and Group 2. In Group 1; 95% CI of intercept and slope were found as (-1.41 to -0.30) and (1.03 to 1.22), respectively. In Group 2; 95% CI of intercept and slope were found as (-1.33 to -0.31) and (1.01 to 1.17), respectively. HPLC and TINIA methods could not be used interchangeable without affecting patient results and outcome in both Group 1 and Group 2. Conclusion: Our study concluded that TINIA and HPLC methods could not be used interchangeably without affecting patient results and outcome. Because of the methodology that clinical laboratories are used to, clinicians and clinical biochemists should collaborate on managing diabetes mellitus regarding diagnosis, treatment, and follow-up.

Validation of salivary glucose as a screening tool of diabetes mellitus

Background: Improved prognosis and delay of clinical complications in diabetes mellitus can be ensured by early screening and regular monitoring after diagnosis. This requires venipuncture at regular intervals of time causing anxiety and discomfort to the patient. Hence, development of a painless, non-invasive procedure is desirable for which saliva is a potential tool. Also, this would provide easy and cost-effective means for large scale screening and epidemiological intervention.

Aim: To measure fasting plasma glucose (FPG) and compare and correlate with salivary glucose levels in normal and diabetic individuals. Also, the correlation between glycated hemoglobin (HbA1c) and salivary glucose is studied in the diabetics and controls.

Methods: Blood and salivary glucose was estimated by GOD-POD method and glycated hemoglobin by HPLC. Statistical analysis was done on SPSS 16. Mean, Standard deviation, independent t test, ANOVA (f test), Pearson’s correlation coefficient along with regression analysis was carried out and comparison was done between the control and diabetic groups and the different subgroups within the diabetic group.

Results: A significant difference between the salivary glucose levels in subjects indicating that a deranged glycemic status is reflected in saliva. Also, salivary glucose increases in proportion to an increase in the FPG and HbA1C of the diabetics. The regression coefficient was calculated and a formula was derived for prediction of FPG and HbA1c using salivary glucose.

Conclusion: Saliva can be used as a screening tool for diabetes. Standardization of the technique and setting up a reference range will also make it useful in diagnosing diabetes mellitus.

Diagnostic Accuracy of Point-of-Care Tests Measuring Glycosylated Haemoglobin (HbA1c) for Glycemic Control: A Field Study in India

Objectives This study was performed to estimate diagnostic accuracy of the two commercially available point-of-care tests to identify poor glycemic control defined by HbA1c levels, with high-performance liquid chromatography (HPLC) as a reference. Settings The study was carried at two locations, general medical outpatient department of a teaching medical college in Bhopal (urban), and a primary health care centre in a rural area in the state of Madhya Pradesh, India. Participants All individuals with diabetes mellitus who presented to the health care facility for assessment of glycemic control. We compared HbA1c estimated from two index tests (Hemocue Hb 501, Sweden; SD Biosensor, South Korea) from capillary blood samples with HPLC performed from venous blood, as a reference standard. Primary and secondary outcome measures Diagnostic properties of index tests such as sensitivity, specificity, positive and negative predictive value and diagnostic accuracy for identifying poor glycemic control were primary outcome measures. Lin's concordance correlation coefficient (CCC) was secondary outcome measure. Results Out of 114 patients, all received reference standard - 103 patients received Hemocue A1C test and 110 patients received SD Biosensor test. Overall both the index tests had similar diagnostic accuracy estimates. The area under the Receiver Operating Curve for SDA1c device was 0.935 (95% CI 0.886-0.983), and for Hemocue device was 0.938 (95% CI 0.893-0.984). The Hemocue device HbA1c value of above 7.0 (positive) correctly predicted poor glycemic control 92% times (81.58% for SD device). There were 4 vs. 11 device failures and 14 vs. 12 failures with SD and Hemocue, respectively. Ambient air temperatures were no different for the device test failures. Conclusions Commercially available point-of-care tests evaluated in this study are comparable and an acceptable alternative to HPLC-based measurements for the assessment of glycemic control. Tests and device failure rates of both the index tests are similar.

Electrical vestibular nerve stimulation as an adjunctive therapy in the management of type 2 diabetes

OBJECTIVES

Vestibular nerve stimulation using the portable battery-operated vestibular nerve stimulator is a sophisticated method noninvasive, safe, and easy to operate. It was hypothesized that vestibular nerve stimulation is effective in the management of type 2 diabetes. Hence, the present study was undertaken to determine the effectiveness of vestibular nerve stimulation using portable battery-operated vestibular nerve stimulator in the management of diabetes.

METHODS

The present study was a double-blind randomized controlled trial with 1:1 split between the control and experimental groups. A total of 30 participants with type 2 diabetes were part of the study after obtaining the written informed consent. After recording the baseline values, the vestibular nerve stimulation was administered to the participants in the intervention group for 90 days. Sham stimulation was administered to the control group for 90 days. Outcome measures were recorded after 30 days and after 90 days of the intervention in both the groups.

RESULTS

There was significant decrease in the total body weight, fasting, postprandial blood glucose, glycosylated hemoglobin levels, leptin, very low density lipoproteins levels followed by the intervention. There was significant improvement in both spatial and verbal memory scores. Depression and stress scores and systolic blood pressure decreased and remained in normal limits.

CONCLUSIONS

The study results have proven multimodal action of vestibular stimulation. It not only acts on regulation of the glucose metabolism but also can regulate the autonomic activity and improve cognition and relieve stress. This is the interesting finding of our study, which needs detailed further research to support implementation of vestibular nerve stimulation as an adjunctive therapy in the management of diabetes.

Magnetite-Quantum Dot Immunoarray for Plasmon-Coupled-Fluorescence Imaging of Blood Insulin and Glycated Hemoglobin

New microarray chip strategies that are sensitive and selective and that can measure low levels of important biomarkers directly in a blood sample are significant for improving human health by allowing timely diagnosis of an abnormal condition. Herein, we designed an antibody-aptamer immunoarray chip to demonstrate simultaneous measurement of blood insulin and glycated hemoglobin (HbA1c) levels relevant to diabetic and prediabetic disorders using a surface plasmon microarray with validation by fluorescence imaging. To accomplish both surface plasmon and fluorescence imaging on the same sample, we decorated magnetite nanoparticles with quantum dots for covalent immobilization of aptamers for subsequent capture and isolation of the aptamers specific for insulin and HbA1c markers from 20-times diluted whole blood samples. Direct clinically relevant analysis, along with fluorescent imaging of the two markers, was achieved by this new immunoarray platform. The limit of detection was 4 pM for insulin and 1% for HbA1c. Examination of cross-talk using thrombin and platelet-derived growth factor confirmed that the designed immunoarray was highly selective for insulin and HbA1c. Surface plasmon kinetic analysis provided apparent binding constants of 0.24 (±0.08) nM and 37 (±3) μM, respectively, for the binding of insulin and HbA1c onto their surface immobilized monoclonal antibodies. Thus, quantitative imaging of ultralow levels of blood biomarker levels with binding kinetics is uniquely obtained in the designed immunoarray chip. In conclusion, this report demonstrates considerable significance of the developed magnetite-quantum dot-bioconjugate strategy for clinical diagnostics of whole blood biomarkers with characterization of molecular binding interactions.

Association of lipocalin-2 level, glycemic status and obesity in type 2 diabetes mellitus

BACKGROUND

Management of type 2 diabetes mellitus aims to maintain a normal glycemic status, which if not, it may lead to acute and/or chronic diabetic complications. Earlier studies found Lipocalin-2 elevated in complications associated with type 2 diabetes mellitus such as ischemic heart disease. These lipocalin-2 changes had been linked to obesity and uncontrolled diabetes. So, it could be useful to understand the effect of glycemic control and obesity on lipocalin-2.

METHODS

This was a case control study. Fifty-seven patients with type 2 diabetes and 30 non-diabetic controls participated after getting a written consent. Weight (kg), height (m) and waist circumference (cm) were measured then the body mass index (kg/m2) was determined. Blood samples were collected after an overnight fasting. HbA1c, lipid profile and serum creatinine were measured using enzymatic methods. Lipocalin-2 was measured using sandwich ELISA.

RESULTS

Lipocalin-2 was found significantly higher in patients with type 2 diabetes (P = 0.001). However, it had no significant correlation with any of the studied variables. Females had elevated BMI compared to males in the patients group (P < 0.001). HbA1c, serum creatinine, LDL and total cholesterol were elevated in patients with diabetes (P < 0.02). HDL was lower in the patients (P = 0.002). Significant elevation in HbA1c was found in male patients (P = 0.028) compared to female patients. Patients were further classified into controlled, uncontrolled diabetics, obese and non-obese. There was a significant elevation in waist circumference in uncontrolled diabetics compared to controlled ones. Lipocalin-2 had no significant changes between controlled and uncontrolled diabetics nor non-obese and obese patients.

CONCLUSION

Patients with type 2 diabetes mellitus have elevated level of serum lipocalin-2. There was no significant association found between lipocalin-2 and glycemic control nor obesity.

Performance of point-of-care HbA1c test devices: implications for use in clinical practice - a systematic review and meta-analysis

BACKGROUND

Point-of-care (POC) devices could be used to measure hemoglobin A1c (HbA1c) in the doctors' office, allowing immediate feedback of results to patients. Reports have raised concerns about the analytical performance of some of these devices. We carried out a systematic review and meta-analysis using a novel approach to compare the accuracy and precision of POC HbA1c devices.

METHODS

Medline, Embase and Web of Science databases were searched in June 2015 for published reports comparing POC HbA1c devices with laboratory methods. Two reviewers screened articles and extracted data on bias, precision and diagnostic accuracy. Mean bias and variability between the POC and laboratory test were combined in a meta-analysis. Study quality was assessed using the QUADAS2 tool.

RESULTS

Two researchers independently reviewed 1739 records for eligibility. Sixty-one studies were included in the meta-analysis of mean bias. Devices evaluated were A1cgear, A1cNow, Afinion, B-analyst, Clover, Cobas b101, DCA 2000/Vantage, HemoCue, Innovastar, Nycocard, Quo-Lab, Quo-Test and SDA1cCare. Nine devices had a negative mean bias which was significant for three devices. There was substantial variability in bias within devices. There was no difference in bias between clinical or laboratory operators in two devices.

CONCLUSIONS

This is the first meta-analysis to directly compare performance of POC HbA1c devices. Use of a device with a mean negative bias compared to a laboratory method may lead to higher levels of glycemia and a lower risk of hypoglycaemia. The implications of this on clinical decision-making and patient outcomes now need to be tested in a randomized trial.

Significance of HbA1c Test in Diagnosis and Prognosis of Diabetic Patients

Diabetes is a global endemic with rapidly increasing prevalence in both developing and developed countries. The American Diabetes Association has recommended glycated hemoglobin (HbA1c) as a possible substitute to fasting blood glucose for diagnosis of diabetes. HbA1c is an important indicator of long-term glycemic control with the ability to reflect the cumulative glycemic history of the preceding two to three months. HbA1c not only provides a reliable measure of chronic hyperglycemia but also correlates well with the risk of long-term diabetes complications. Elevated HbA1c has also been regarded as an independent risk factor for coronary heart disease and stroke in subjects with or without diabetes. The valuable information provided by a single HbA1c test has rendered it as a reliable biomarker for the diagnosis and prognosis of diabetes. This review highlights the role of HbA1c in diagnosis and prognosis of diabetes patients.

Effect of the different assays of HbA1c on diabetic patients monitoring

BACKGROUND

HbA1c test is widely used for glycemic monitoring of diabetic patients. This study aimed to evaluate clinical performance of different assays for classification of patients into controlled and uncontrolled group base on ADA recommendations.

METHOD

A total of 154 samples from patients with diabetes type 2 with HbA1c concentration covering the whole clinical range were analyzed by four commercially methods; D-10 Hb A1c (Bio-Rad Laboratories), Cobas Integra 400 (Roche Diagnostics), NycoCard Reader II (Axis-Shield) and DS5 (Drew Scientific). For each individual assay, patient's results were classified into controlled and uncontrolled groups (less or more than three decision levels; 6.5 %, 7 % and 8 %) compared to D10 results as reference method. The frequency of each group and also sensitivity, specificity, negative and positive predictive value were estimated.

RESULTS

We found a significant correlation between assays (r: 0.937-0.945). Sensitivity, specificity, and positive and negative predictive values of the evaluated method to identify uncontrolled patients were as follows: 49.2-95.7 %, 86.5-100 %, 89.1-100 %, and 52.9-93.3 %; respectively.

CONCLUSIONS

Results show that some HbA1c assays capability to classify diabetic patients according to HbA1c level is still unacceptable.