The diagnostic accuracy of HbA1c , compared to the oral glucose tolerance test, for screening for type 2 diabetes mellitus in Africa-A systematic review and meta-analysis

HbA1c comparable to fasting glucose in the external validation of the African Diabetes Risk Score and other established risk prediction models in Black South Africans

BACKGROUND

The use of non-invasive risk scores to detect undiagnosed type 2 diabetes (T2D) ensures the restriction of invasive and costly blood tests to those most likely to be diagnosed with the disease. This study assessed and compared the performance of the African Diabetes Risk Score (ADRS) with three other diabetes risk prediction models for identifying screen-detected diabetes based on fasting plasma glucose (FPG) or glycated haemoglobin (HBA1c).

METHODS

Age, sex, waist circumference, body mass index, blood pressure, history of diabetes and physical activity levels from the SA-NW-PURE study were used to externally validate the ADRS and other established risk prediction models. Discrimination was assessed and compared using C-statistics and nonparametric methods. Calibration was assessed using calibration plots, before and after recalibration.

RESULTS

Nine hundred and thirty-seven participants were included; 14% had prevalent undiagnosed T2D according to FPG and 26% according to HbA1c. Discrimination was acceptable and was mostly similar between models for both diagnostic measures. The C-statistics for diagnosis by FPG ranged from 0.69 for the Simplified FINDRISC model to 0.77 for the ADRS model and 0.77 for the Simplified FINDRISC model to 0.79 for the ADRS model for diagnosis by HbA1c. Calibration ranged from acceptable to good, though over- and underestimation were present. All models improved significantly following recalibration.

CONCLUSIONS

The models performed comparably, with the ADRS offering a non-invasive way to identify up to 79% of cases. Based on its ease of use and performance, the ADRS is recommended for screening for T2D in certain Black population groups in South Africa. HbA1c as a means of diagnosis also showed comparable performance with FPG. Therefore, further validation studies can potentially use HbA1c as the standard to compare to.

HIV, malnutrition, and noncommunicable disease epidemics among tuberculosis-affected households in east and southern Africa: A cross-sectional analysis of the ERASE-TB cohort

BACKGROUND

As a result of shared social and structural risk factors, people in households affected by tuberculosis may have an increased risk of chronic conditions; at the same time, tuberculosis screening may be an opportunity for interventions. We sought to describe the prevalence of HIV, nutritional disorders, and noncommunicable diseases (NCDs) among members of tuberculosis-affected households in 3 African countries.

METHODS AND FINDINGS

A part of a multicountry cohort study, we screened for tuberculosis, HIV, nutritional disorders (underweight, anaemia, overweight/obesity), and NCDs (diabetes, hypertension, and chronic lung disease) among members of tuberculosis-affected households aged ≥10 years in Mozambique, Tanzania, and Zimbabwe. We describe the prevalence of these conditions, their co-occurence within individuals (multimorbidity) and household-level clustering. Of 2,109 household contacts recruited, 93% (n = 1,958, from 786 households) had complete data and were included in the analysis. Sixty-two percent were female, median age was 27 years, and 0.7% (n = 14) were diagnosed with co-prevalent tuberculosis. Six percent of household members (n = 120) had previous tuberculosis, 15% (n = 294) were living with HIV, 10% (n = 194) had chronic lung disease, and 18% (n = 347) were anaemic. Nine percent of adults (n = 127) had diabetes by HbA1c criteria, 32% (n = 439) had hypertension. By body mass index criteria, 18% household members (n = 341) were underweight while 29% (n = 549) were overweight or obese. Almost half the household members (n = 658) had at least 1 modifiable tuberculosis risk factor. Sixty-one percent of adults (n = 822) had at least 1 chronic condition, 1 in 4 had multimorbidity. While most people with HIV knew their status and were on treatment, people with NCDs were usually undiagnosed and untreated. Limitations of this study include use of point-of-care HbA1c for definition of diabetes and definition of hypertension based on single-day measurements.

CONCLUSIONS

Households affected by tuberculosis also face multiple other health challenges. Integrated approaches to tuberculosis screening may represent an opportunity for identification and treatment, including prioritisation of individuals at highest risk for tuberculosis to receive preventive therapy.

A Comparative Evaluation of Point-of-Care and Laboratory HbA1c Testing in Diabetes Care: An Indian Perspective

AIM

This study aimed to assess the diagnostic performance of a point-of-care (POC) glycated hemoglobin (HbA1c) device in the Indian population against the standard laboratory (high-performance liquid chromatography {HPLC}) method for the effective management of diabetes in India.

METHODS

This study on the diagnostic accuracy of a POC HbA1c device involved 121 participants. These participants were categorized into two groups according to their HbA1c levels - one group with HbA1c values below 6.5% and another group with HbA1c values equal to or greater than 6.5%. The HbA1c levels in enrolled participants were estimated using both the POC device (HemoCue HbA1c 501; Ängelholm, Sweden: HemoCue AB) and the standard HPLC-based method. The level of agreement and concordance between the two test results were assessed by the Bland-Altman plot and Lin's concordance correlation coefficient. Sensitivity, specificity, diagnostic accuracy, positive likelihood, and negative likelihood ratios of POC-HbA1c device were assessed with a 6.5% HbA1c cut-off.

RESULTS

 The mean HbA1c values obtained by the two methods showed no statistically significant difference with a minimum effect size (Cohen's d = 0.035), indicating there was a negligible difference between these methods. The Bland-Altman plot revealed that most values were within acceptable limits (95% CI: -0.5 to 0.7) and Lin's concordance correlation coefficient showed strong agreement (p < 0.0001). The POC-HbA1c device demonstrated an area under the curve (AUC) of 0.991 (95% CI: 0.953-1.000) with sensitivity, specificity, diagnostic accuracy, positive likelihood, and negative likelihood ratios of 93.62%, 97.30%, 95.87%, 34.64 and 0.07, respectively, compared to the standard diagnostic assay.

CONCLUSIONS

The diagnostic accuracy, sensitivity, and specificity demonstrated by the POC-HbA1c device to the standard HPLC method offers a viable and practical solution for diabetes management in India. Its ability to provide rapid and reliable results at the point of care can improve patient outcomes, reduce healthcare costs, and enhance access to diabetes care, especially in primary care, remote areas, and resource-limited settings of developing countries like India.

Determining the 1-hour post-load glucose which identifies diabetes in Africans: Insight from the Africans in America study

Diagnosing diabetes by shortening the OGTT to 1-h and substituting 1-h post-load glucose (PG) ≥ 209 mg/dL for 2-h PG≥200 mg/dL has been proposed. One-hour PG≥209 mg/dL is from a meta-analysis without any African-descent populations. Our data suggest 1-h PG≥183 mg/dL maybe more optimal for Africans. As with waist circumference guidelines, population-specific thresholds may be appropriate.

Determinants of mortality status and population attributable risk fractions of the North West Province, South African site of the international PURE study

BACKGROUND

Mortality data and comparative risk assessments from sub-Saharan Africa are limited. There is an urgent need for high quality population health surveys to be conducted, to improve the national health surveillance system. Our aim was to perform a comparative risk assesment and report on the mortality status and cause of death data of participants from a South African site of the international Prospective Urban Rural Epidemiology study.

METHODS

1 921 Black participants were included, with a median observational time of 13 years resulting in 21 525 person-years. We performed a comparative risk assessment considering four health status domains: locality (rural vs. urban), socio-economic status (SES) (education and employment), lifestyle factors (physical activity, smoking and alcohol consumption) and prevalent diseases (human immunodeficiency virus (HIV), type 2 diabetes mellitus and hypertension). Next, population-attributable fractions (PAFs) were calculated to determine the mortality risk attributable to modifiable determinants.

RESULTS

577 all-cause deaths occurred. Infectious diseases (28.1% of all deaths) were the most frequent cause of death, followed by cardiovascular disease (CVD) (22.4%), respiratory diseases (11.6%) and cancer (11.1%). The three main contributors to all-cause mortality were HIV infection, high SES and being underweight. HIV infection and underweight were the main contributors to infectious disease mortality and hypertension, the urban environment, and physical inactivity to CVD mortality. HIV had the highest PAF, followed by physical inactivity, alcohol and tobacco use and hypertension (for CVD mortality).

CONCLUSION

This African population suffers from a quadruple burden of disease. Urban locality, high SES, prevalent disease (HIV and hypertension) and lifestyle factors (physical inactivity, tobacco and alcohol use) all contributed in varying degrees to all-cause and cause-specific mortalities. Our data confirm the public health importance of addressing HIV and hypertension, but also highlights the importance of physical inactivity, tobacco use and alcohol consumption as focal points for public health strategies to produce the most efficient mortality reduction outcomes.

HIV and type 2 diabetes: An evolving story

INTRODUCTION

Diabetes is widely reported to be more common in people living with HIV (PLWH). Much of the data supporting this originated during the earlier HIV era. The perceived increased risk of type 2 diabetes is reflected in HIV clinical guidelines that recommend screening for diabetes in PLWH on anti-retroviral therapy (ART). However, international HIV clinical guidelines do not agree on the best marker of glycaemia to screen for diabetes. This stems from studies that suggest HbA1c underestimates glycaemia in PLWH.

METHODS

Within this review we summarise the literature surrounding the association of HIV and type 2 diabetes and how this has changed over time. We also present the evidence on HbA1c discrepancy in PLWH.

CONCLUSION

We suggest there is no basis to any international guidelines to restrict HbA1c based on HIV serostatus. We recommend, using the current evidence, that PLWH should be screened annually for diabetes in keeping with country specific guidance. Finally, we suggest future work to elucidate phenotype and natural history of type 2 diabetes in PLWH across all populations.

Prevalence of chronic conditions and multimorbidity among healthcare workers in Zimbabwe: Results from a screening intervention

The burden of non-communicable diseases (NCDs) in southern Africa is expanding and is superimposed on high HIV prevalence. Healthcare workers are a scarce resource; yet are vital to health systems. There are very limited studies on the burden of chronic conditions among healthcare workers in Africa, and none exploring multimorbidity (≥2 chronic conditions). We describe the epidemiology of infectious (HIV) and non-communicable chronic conditions, and multimorbidity, among Zimbabwean healthcare workers. Healthcare workers (≥18 years) in eight Zimbabwean provinces were invited to a voluntary, cross-sectional health-check, including HIV, diabetes, hypertension and mental health screening. Statistical analyses described the prevalence and risk factors for multimorbidity (two or more of HIV, diabetes, hypertension or common mental disorder) and each condition. Missing data were handled using multiple imputation. Among 6598 healthcare workers (July 2020-July 2022) participating in the health-check, median age was 37 years (interquartile range 29-44), 79% were women and 10% knew they were living with HIV. Half had at least one chronic condition: 11% were living with HIV, 36% had elevated blood pressure, 12% had elevated HbA1c and 11% had symptoms of common mental disorder. The overall prevalence of multimorbidity was 15% (95% CI: 13-17%); 39% (95% CI: 36-43%) among people aged 50 and older. Whilst most HIV was diagnosed and treated, other chronic conditions were usually undiagnosed or uncontrolled. Limiting our definition of multimorbidity to two or more screened conditions sought to reduce bias due to access to diagnosis, however, may have led to a lower reported prevalence than that found using a wider definition. Half of healthcare workers screened were living with a chronic condition; one in seven had multimorbidity. Other than HIV, most conditions were undiagnosed or untreated. Multisectoral action to implement contextually relevant, chronic disease services in Africa is urgently needed. Specific attention on health workers is required to protect and retain this critical workforce.

Early postpartum HbA1c after hyperglycemia first detected in pregnancy-Imperfect but not without value

BACKGROUND

South African women of childbearing age are disproportionally affected by obesity and at significant risk of Type 2 Diabetes Mellitus (T2DM). Unless pregnant, they do not readily undergo screening for T2DM. With a local focus on improved antenatal care, hyperglycemia is often first detected in pregnancy (HFDP). This may erroneously be attributed to Gestational Diabetes Mellitus (GDM) in all without considering T2DM. Glucose evaluation following pregnancy is essential for early detection and management of women with T2DM in whom persistent hyperglycemia is to be expected. Conventional testing with an oral glucose tolerance test (OGTT) is cumbersome, prompting investigation for alternate solutions.

AIM

To compare the diagnostic performance of HbA1c to the current gold standard OGTT in women with HFDP 4-12 weeks post-delivery.

METHODS

Glucose homeostasis was assessed with OGTT and HbA1c in 167 women with HFDP, 4-12 weeks after delivery. Glucose status was based on American Diabetes Association criteria.

RESULTS

Glucose homeostasis was assessed at 10 weeks (IQR 7-12) after delivery. Of the 167 participants, 52 (31%) had hyperglycemia, which was comprised of 34 (20%) prediabetes and 18 (11%) T2DM. Twelve women in the prediabetes subgroup had diagnostic fasting plasma glucose (FPG) and 2-hour plasma glucose (2hPG), but in two-thirds of the patients (22/34) only one time point proved diagnostic. The FPGs and the 2hPGs of six women with HbA1c-based T2DM were both within the prediabetes diagnostic range. According to the HbA1c measurements, 85% of 52 participants with gold standard OGTT defined hyperglycemia (prediabetes and T2DM) as well as 15 of 18 women with postpartum persistent T2DM were correctly classified. According to FPG, 15 women with persistent hyperglycemia would have been missed (11 with prediabetes and four with T2DM; 29%). When compared to an OGTT, a single HbA1c of 6.5% (48mmol/mol) postpartum demonstrated a sensitivity of 83% and specificity of 97% for the identification of T2DM.

CONCLUSION

HbA1c may improve access to postpartum testing in overburdened clinical settings where the required standards of OGTT cannot be guaranteed. HbA1c is a valuable test to detect women who will benefit most from early intervention but cannot unequivocally replace OGTT.

Diagnostic accuracy of two confirmatory tests for diabetes mellitus in adult Ugandans with recently diagnosed tuberculosis

Objective

The optimal confirmatory tests for diabetes mellitus (DM) in patients with tuberculosis (TB) vary across populations. This study aimed to evaluate the performance of two confirmatory tests for DM against the oral glucose tolerance test (OGTT) as the reference test in adult Ugandans with recently diagnosed TB.

Methods

A total of 232 adult participants receiving TB treatment underwent initial screening for DM with random blood glucose (RBG) measurement. Participants with a RBG level ⩾6.1 mmol/l received additional screening with fasting blood glucose (FBG), laboratory-measured glycated haemoglobin (HbA1c) and an OGTT. Using the latter as the gold standard and reference test, we evaluated the diagnostic accuracy of laboratory-measured HbA1c and FBG.

Results

Of the 232 participants initially screened for DM using RBG measurement, 117 participants (50.4%) had RBG level ⩾6.1 mmol/l and were scheduled to return for additional blood glucose testing. Of these, 75 (64.1%) participants returned for FBG and HbA1c measurements. A diagnosis of DM was made in 32 participants, corresponding to a prevalence of 13.8% [95% CI 9.9-18.9].The areas under the curve (AUC) for FBG and laboratory-measured HbA1c were 0.69 [95% CI 0.47-0.90] and 0.65 [95% CI 0.43-0.87], respectively. The sensitivity and specificity of a FBG level of ⩾7 mmol/l were 57.1% [95% CI 18.4-90.1] and 74.6% [95% CI 62.5-84.5], respectively, whereas the sensitivity and specificity for laboratory-measured HbA1c of ⩾6.5 mmol/l (48 mmol/mol) were 14.3% [95% CI 0.40-57.9] and 95.3% (86.9-99.0%), respectively.

Conclusion

FBG may be better than laboratory-measured HbA1c in confirming DM in adult Ugandans with recently diagnosed TB. However, because of the small study sample size, larger studies evaluating the diagnostic utility of these diabetes screening tests in adult Ugandans with TB are needed to confirm these findings.

Differential Effects on HbA1c Detection by HPLC and Capillary Electrophoresis in Five Types of Hb Variants in China

Objective

Hemoglobin A1c (HbA1c) can be used to evaluate blood glucose control. Its measurement will be affected by many factors, but Hb variation is the most critical factor. This study aimed to explore the types of variants found in routine work and their impact on test results.

Methods

Samples with abnormal HbA1c chromatograms found in routine testing were tested with high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) and then further tested with polymerase chain reaction (PCR) and sequencing.

Results

Five recessive heterozygous mutations were identified after PCR and sequencing. Hb Riccarton-II (a mutation in the HBA2 gene), Hb E, Hb G-Coushatta, Hb G-Taipei, and Hb North Manchester (a mutation in the HbB gene) were identified. All HbA1c values of these variants detected by HLC-723 G8 (HPLC method) were lower than those of Sebia Capillarys 2 FP (C2FP, CE method) with P &lt; .0001.

Conclusion

Five Hb mutations were identified in our routine HbA1c test, and their HPLC detection values were significantly lower than those obtained with the CE method.

Tungsten Disulfide Decorated Screen-Printed Electrodes for Sensing of Glycated Hemoglobin

Diabetes is a global menace, and its severity results in various disorders including cardiovascular, retinopathy, neuropathy, and nephropathy. Recently, diabetic conditions are diagnosed through the level of glycated hemoglobin. The level of glycated hemoglobin is determined with enzymatic methodology. Although the system is sensitive, it has various restrictions such as long processing times, expensive equipment required for testing, and complex steps involved in sample preparation. These limitations are a hindrance to faster results. The limitations of the developed methods can be eliminated through biosensors. In this work, an electrochemical platform was fabricated that facilitates the identification of glycated hemoglobin protein in diabetic patients. The working electrode on the integrated circuit was modified with molecularly imprinted polymer decorated with tungsten disulfide nanoparticles to enhance its analytical properties. The analytical properties of the biosensor were studied using electrochemical techniques. The obtained detection limit of the nanoelectronic sensor was 0.01 pM. The calculated sensitivity of the biosensor was observed to be 0.27 μA/pM. Also, the sensor promises to operate in a dynamic working concentration range and provide instant results.