Prevalence of hemoglobin variants in a diabetic population at high risk of hemoglobinopathies and optimization of HbA1c monitoring by incorporating HPLC in the laboratory workup

Chronic disease prevalence in a population with structural hemoglobin disorders undergoing diabetes diagnosis: A bayesian approach

Background

Structural disorders of hemoglobin are a group of rare and fatal genetic diseases that disrupt the transport and exchange of oxygen in the blood, causing tissue damage and ultimately leading to chronic conditions. The hemoglobin (Hb) S variant predominantly impacts individuals of Afro-descendant heritage. A significant concentration of the Afro-descendant population in Colombia, notably 12.5 %, is found in the city of Cali. Previous research has identified this city's structural hemoglobin disorders prevalence rate of 3.78 %. The aim of this study was to determine the prevalence of HbC, HbS, HbF, and HbA2 variants within a population who underwent HbA1c testing, as well as the prevalence of chronic diseases among patients with these hemoglobin alterations, at a high-complexity hospital in the city of Cali from 2015 to 2019.

Methods

A descriptive observational study was conducted, involving a study population that comprised patients with both suspected and monitored diagnoses of diabetes. The cohort was selected from a high-complexity hospital in Cali. A total of 15,608 patients were included in the analysis, all of whom underwent HbA1C measurement through capillary electrophoresis, which also offers an indirect diagnosis of certain structural disorders of hemoglobin. Bayesian methods were employed for frequency analysis.

Results

Among the 15,608 patients assessed, 63.6 % (n = 9920) were women. The overall prevalence of structural hemoglobin disorders was 1.98 % (n = 287, 95 % CI = 1.77 %-2.21 %). The co-occurrence of diabetes and kidney disease emerged as the most prevalent combination of pathologies observed in individuals with HbC, for both men and women across various age groups: 18-42 (58.3 % and 50.0 % respectively), 43-55 (50.0 % for both), 56-65 (50.0 % and 37.5 % respectively), and >65 years (66.7 % and 57.1 % respectively).

Conclusions

The observed prevalence of the studied variants exceeded 1 %, a threshold underscored by the World Health Organization (WHO) as epidemiologically significant. Among HbC and HbS-positive patients, the elevated prevalence of diabetes and kidney disease is a guiding factor in developing proactive prevention strategies.

Type 2 Diabetes Mellitus with HbJ trait: A management conundrum

Optimal glycaemic control is crucial in patients with diabetes mellitus (DM) to avoid episodes of hypoglycaemia and both micro- and macrovascular complications. Diabetic control relies mainly on the evaluation of haemoglobin A1c (HbA1c), which is unfortunately unreliable in patients with haemoglobinopathies. This case report describes a patient with type 2 DM and haemoglobin J (HbJ) trait, which resulted in erratic HbA1c values throughout her follow-up. Other approaches, such as self-blood glucose monitoring, are needed to evaluate glycaemic control instead of relying on HbA1c alone to guide the management DM in these patients.

Low HbA1c in poorly controlled type 1 diabetes mellitus in a child

Haemoglobin A1c (HbA1c), glycosylated haemoglobin, is a crucial tool in monitoring long-term glycaemic control in diabetic patients. Studies have also demonstrated that it has a role in the prognostication of diabetic microvascular complications. However, certain conditions can interfere with HbA1c interpretation. Haemoglobin variants and disorders are important conditions that can lead to HbA1c misinterpretation. In this report, we describe an uncontrolled diabetic child who was found to have a low value of HbA1c and how this affected the clinical decisions regarding his management.

Accurate and Rapid Measurement of Glycated Hemoglobin Using HLC-723 G11 Variant Mode

Background

Type II diabetes mellitus causes many complications, and its prevalence continues to increase in Korea. Accurate measurement of glycated Hb (HbA1c) is important because of its usefulness in diagnosis, follow-up, and prediction of prognosis. We tested the analytical performance of the HLC-723 G11 Variant Mode (G11vr; Tosoh Bioscience, Inc., Tokyo, Japan), recently introduced to Korea, in detecting HbA1c.

Methods

We evaluated precision, linearity, carry-over, and turnaround time. Using 208 samples, including 108 flagged samples, we compared HbA1c concentrations from four analyzers through correlation analysis: G11vr, HLC-723 G8 Variant Mode (G8vr, Tosoh Bioscience), HLC-723 G11 Standard Mode (G11st, Tosoh Bioscience), and HLC-723 G8 Standard Mode (G8st, Tosoh Bioscience). We used HPLC mass spectrometry (MS) and capillary electrophoresis (CE) to confirm the HbA1c concentrations of 15 additional known Hb variant samples.

Results

Repeatability (% CV) in measuring low- and high-concentration controls was 0.57% and 0.35%, respectively; within-laboratory precision was 0.86% and 0.69%, respectively. In a linearity test, the coefficient of determination was 0.9999 (measurement range: 3.64% to 18.59%) for HbA1c. The correlations between G11vr and other analyzers were weaker for flagged samples than for non-flagged samples. The carry-over effect was less than 0.4%. Turnaround time for a single sample was lower in G11vr (one minute) than in G8vr (1.6 minutes). For 15 samples with Hb variants, G11vr HbA1c results were more similar than those of other analyzers to HPLC-MS and CE results.

Conclusions

G11vr showed adequate performance and rapid turnaround time in measuring HbA1c.

The Prevalence and Role of Hemoglobin Variants in Biometric Screening of a Multiethnic Population: One Large Health System's Experience

OBJECTIVES

To characterize and quantitate hemoglobin (Hb) variants discovered during biometric hemoglobin A1c (HbA1c) analyses in a large multiethnic population with a focus on the effect of variants on testing method and results.

METHODS

In total, 13,913 individuals had their HbA1c measured via ion-exchange high-performance liquid chromatography. Samples that had a variant Hb detected or HbF fraction more than 25% underwent variant Hb characterization and confirmation by gel electrophoresis. RBC indices were also evaluated for possible concomitant thalassemia.

RESULTS

Of the 13,913 individuals evaluated, 524 (3.77%) had an Hb variant. The prevalence of each variant was as follows: HbS trait (n = 396, 2.85%), HbSS disease (n = 4, 0.03%), HbC trait (n = 85, 0.61%), HbCC disease (n = 2, 0.01%), HbSC disease (n = 5, 0.04%), HbE trait (n = 18, 0.13%), HbD or G trait (n = 9, 0.06%), HbS β-thalassemia + disease (n = 1, 0.01%), hereditary persistence of HbF (n = 2, 0.01%), and HbMontgomery trait (n = 1, 0.01%). Concomitant α-thalassemia was detected in 20 (3.82%) of the 524 individuals with an Hb variant.

CONCLUSIONS

This study represents one of the largest epidemiologic investigations into the prevalence of Hb variants in a North American metropolitan, multiethnic workforce and their dependents and reinforces the importance of method selection in populations with Hb variants.

HbA1c levels in individuals heterozygous for hemoglobin variants

Summary Objective: To evaluate the levels of glycated hemoglobin (HbA1c) in patients heterozygous for hemoglobin variants and compare the results of this test with those of a control group. Method: This was an experimental study based on the comparison of HbA1c tests in two different populations, with a test group represented by individuals heterozygous for hemoglobin variants (AS and AC) and a control group consisting of people with electrophoretic profile AA. The two populations were required to meet the following inclusion criteria: Normal levels of fasting glucose, hemoglobin, urea and triglycerides, bilirubin > 20 mg/dL and non-use of acetylsalicylic acid. 50 heterozygous subjects and 50 controls were evaluated between August 2013 and May 2014. The comparison of HbA1c levels between heterozygous individuals and control subjects was performed based on standard deviation, mean and G-Test. Results: The study assessed a test group and a control group, both with 39 adults and 11 children. The mean among heterozygous adults for HbA1c was 5.0%, while the control group showed a rate of 5.74%. Heterozygous children presented mean HbA1c at 5.11%, while the controls were at 5.78%. G-Test yielded p=0.93 for children and p=0.89 for adults. Conclusion: Our study evaluated HbA1c using ion exchange chromatography resins, and the patients heterozygous for hemoglobin variants showed no significant difference from the control group.

Comparison of four chromatographic methods used for measurement of glycated hemoglobin

This parameter’s results accuracy has a special importance in the management of diabetic patients since targets for optimal glycemic control are established using HbA1c values. Several error sources can influence the obtained value, some of them can be counteracted (ex. pipetting errors, storage), and others should be taken into consideration at the interpretation of the result (ex. presence of hemoglobin variants). The aim of this study was to compare four chromatographic methods regarding the costs and the influence of certain error sources on the accuracy of the result. Materials and methods: Samples and controls were analyzed using Variant I, Micromat II and In2it (Bio-Rad) systems, and the BIOMIDI reagent kit for HbA1c measurement. Results: Positive correlation could be observed comparing the results obtained using different methods, except the patients presenting elevated HbF. Pipetting errors modify the results up to 5% in case of Variant I, and up to 10% in case of Micromat II in the tested range. One day of improper storage at room temperature causes 3% deviation from the actual value using the Variant I analyzer and 5% in case of Micromat II and In2it equipment. As a conclusion, depending on the number of samples, automated chromatographic analyzers are the most appropriate equipments for the determination of HbA1c.