People living with sickle cell trait may be at risk of having prediabetes or diabetes missed because a commonly used blood-sugar test can significantly underestimate their glucose levels, a new study by Ghanaian researchers has found.
The study, presented at ADLM 2026 in Anaheim, California, found that immunoturbidimetry—a laboratory method commonly used to measure HbA1c — produced substantially lower results in people with sickle cell trait than high-performance liquid chromatography (HPLC).
The researchers warned that the discrepancy could result in people with sickle cell trait being wrongly classified as having normal blood sugar, potentially leading to missed diagnoses of prediabetes and diabetes.
The finding could have important implications for Nigeria, Ghana and other parts of West Africa, where sickle cell trait is common.
Dr Elikem Kumahor, lead author of the study and a specialist laboratory physician at Korle Bu Teaching Hospital in Accra, said the findings were particularly important for Ghana, where about two per cent of newborns have sickle cell disease and an estimated 30 per cent of the population carries sickle cell trait.
“However, the influence of haemoglobin variants on HbA1c testing hasn’t been well characterised in our region,” Dr. Kumahor said.
HbA1c is widely used to assess average blood-sugar levels over two to three months and to diagnose and monitor diabetes without requiring patients to fast.
However, the Ghanaian researchers found a significant difference between the two laboratory methods among people with sickle cell trait.
The study examined 1,283 HbA1c tests from adults at a tertiary hospital in Accra during January and February 2026.
Researchers initially tested the samples using HPLC, which can detect haemoglobin variants. Samples suspected of containing variants were subsequently tested using immunoturbidimetry, while haemoglobin electrophoresis was used to confirm sickle cell trait.
Of the participants analysed, 198 had sickle cell trait and 1,027 had normal haemoglobin. Another 58 people with other haemoglobin variants were excluded.
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Among people with normal haemoglobin, the two testing methods produced broadly similar HbA1c results. The difference, however, was striking among those with sickle cell trait.
Their average HbA1c was 5.1 per cent using immunoassay, compared with 5.9 per cent using HPLC. So, the difference changed the classification of a substantial number of patients.
Using immunoassay, only 22 of the 198 people with sickle cell trait, or 11.1 per cent, were classified as having prediabetes. With HPLC, however, 68 people, or 34.5 per cent, fell into the prediabetes category.
The disparity was even more concerning for diabetes. HPLC identified eight participants, or four per cent, as meeting the diabetes threshold, while none were classified as diabetic using immunoassay.
Dr Kumahor said the findings suggest that the laboratory method used to measure HbA1c can have important consequences for diagnosing people who carry the sickle cell gene.
The researchers said the findings should prompt clinicians and laboratories to consider haemoglobin variants when interpreting HbA1c results. They recommended laboratory methods that take such variants into account, including HPLC or mandatory reflex-testing algorithms.
Sickle cell trait is prevalent across much of sub-Saharan Africa, meaning limitations in HbA1c testing could potentially affect diabetes screening in other countries across the region.
Dr Kumahor noted that HbA1c is increasingly used by clinicians as a convenient, non-fasting test for diagnosing and monitoring diabetes. However, he cautioned that its clinical usefulness may not be the same in populations where haemoglobin variants are widespread.
The researchers also recommended that people living with diabetes, as well as those undergoing routine screening, have their haemoglobin genotype taken into consideration when HbA1c testing is performed.
Sickle cell trait occurs when a person inherits one copy of the sickle cell gene. Unlike sickle cell disease, carriers generally do not develop the chronic illness associated with inheriting two copies of the gene.
Although the study is preliminary, the researchers said the findings highlight the need for laboratories and healthcare providers to understand how haemoglobin variants can affect HbA1c measurements, particularly in regions where the trait is widespread.
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