---
title: A1C Tests Can Read Low in People With Sickle Cell Trait, Depending on the Lab Method
description: A study of 1,283 tests in Accra found immunoassays read A1C lower in people with sickle cell trait than HPLC did on the same samples.
author: Dr Marina Nani (Editor-in-Chief)
date: 2026-07-29T09:00:00.000Z
updated: 2026-07-29T09:28:51.139Z
canonical: https://richhealthmagazine.com/article/sickle-cell-trait-a1c-lab-method
image: https://cdn.nanimediahouse.com/pexels-a-medical-professional-analyzing-a-blood-sample-in-a-bright--9629674.jpg
categories: Everyday Wellness
content_type: News
region: Global
publication: Rich Health Magazine
schema_type: Article
---

Eight people whose blood was tested at a teaching hospital in Accra met the threshold for diabetes on one laboratory method. Measured a second way, none of them did. The samples were the same. What differed was the machine the laboratory ran them on.

The finding comes from a review of 1,283 consecutive A1C tests taken from adult patients at Korle Bu Teaching Hospital in January and February this year, presented on 28 July at the Association for Diagnostics and Laboratory Medicine's annual meeting in Anaheim, California. The A1C test measures how much glucose has attached to hemoglobin in the blood, which gives an average of glucose levels over roughly the previous three months, and it is used both to diagnose diabetes and to monitor it. Hemoglobin is also where sickle cell trait lives. People with the trait carry one copy of the variant gene, usually have no symptoms, and are not the same as people with sickle cell disease.

## The Two Methods Agreed, Except in One Group

Every sample was first measured on a high performance liquid chromatography platform, or HPLC, which detects hemoglobin variants automatically. The 256 samples in which a variant was suspected were then measured again using immunoturbidimetric assays, a common laboratory technique. Hemoglobin electrophoresis confirmed sickle cell trait in 198 of the patients. Another 1,027 had normal hemoglobin, and 58 with other variants were set aside.

In the patients with normal hemoglobin, the two methods barely differed. In the 198 with sickle cell trait, the immunoassay read consistently lower: a mean A1C of 5.1 percent against 5.9 percent by HPLC. Pre-diabetes begins at 5.7 percent and diabetes at 6.5 percent, so the gap fell across both lines. By immunoassay, 11.1 percent of the trait group, 22 of the 198, were classified as pre-diabetic; by HPLC, 34.5 percent, or 68 of them, were. At the diabetes threshold, HPLC put 4 percent of the group, eight people, over the line. The immunoassay put none of them there.

"Our study indicates that relying on immunoassays alone likely contributes to a significant underdiagnosis of diabetes," said Dr. Elikem Kumahor, the lead author and a specialist laboratory physician at Korle Bu. He described the work as preliminary.

## Only One Method on the Certifier's List Is Affected by the Trait

A1C methods carry certification from the National Glycohemoglobin Standardization Program, and a sample used to diagnose diabetes in the United States has to be measured by a certified method. The program keeps [a table of the 20 methods most often used to measure A1C](https://ngsp.org/interf.asp) and whether each is thrown off by sickle cell trait, by hemoglobin C, E or D trait, or by raised fetal hemoglobin. The program counts a deviation of more than plus or minus 6 percent at 6 or 9 percent A1C as clinically significant.

On that table, updated in June, one method of the 20 is marked as affected by sickle cell trait: the Siemens DCA Vantage. The other 19 are marked no.

Which method a laboratory owns therefore decides whether a patient's trait shows up in their result at all. The program puts the same point to doctors and patients directly: anyone wanting to know how accurate a given A1C method is for patients with hemoglobin variants should first find out which method their laboratory is using. Where a patient does have a variant, it advises, the laboratory should use a method that is not affected by it.

## About 8 Percent of African American Babies Are Born With the Trait

About 30 percent of Ghanaians carry sickle cell trait, Kumahor said, and about 2 percent of newborns there have sickle cell disease. In the United States, [about 8 percent of African American babies are born with sickle cell trait](https://www.niddk.nih.gov/health-information/professionals/clinical-tools-patient-management/diabetes/sickle-cell-trait-hemoglobinopathies-diabetes), according to the National Institute of Diabetes and Digestive and Kidney Diseases, and about 12.7 percent of African American adults have diabetes. People of Southeast Asian descent more often carry hemoglobin E, a different variant on the same list.

"However, the influence of hemoglobin variants on HbA1c testing hasn't been well characterized in our region," Kumahor said.

## The Researchers and the Certifier Want the Same Thing

Kumahor's recommendation is that laboratories serving populations where variants are common adopt methods that account for them, such as HPLC, or use reflex testing algorithms that trigger a second test when a variant is suspected. He also said that patients who have diabetes or are screened for it routinely should have their hemoglobin genotype tested, and that knowing where the testing falls short would help shape protocols in Ghana and elsewhere in West Africa.

The standardization program's own guidance points the same way. It tells laboratories to weigh the characteristics of the population they serve when they choose an assay, naming a high prevalence of hemoglobinopathies as one of the things that should count.

"HbA1c testing is currently being accessed by clinicians as a non-fasting glucose test for the diagnosis and monitoring of diabetes; however, its clinical utility may not be universally applicable in regions with a high prevalence of hemoglobin variants," Kumahor said.

More on the association's work is at [myadlm.org](https://myadlm.org)

## FAQ

**Q: Does sickle cell trait affect the A1C test?**
It can, but whether it does depends on the method the laboratory uses. In the Accra study, immunoturbidimetric assays read lower in people with the trait than HPLC did on the same samples. On the standardization program's current list of the 20 most used methods, only one is marked as affected by the trait.

**Q: Which hemoglobin variants affect A1C results?**
The standardization program tracks four traits, hemoglobin S, C, E and D, along with raised fetal hemoglobin. The effect depends on both the variant and the specific method, which is why the program publishes them method by method.

**Q: What else can throw off an A1C result?**
Anything that shortens the life of red blood cells, such as recovery from serious blood loss or hemolytic anemia, lowers A1C readings whatever method is used. Chemically altered hemoglobin, such as the carbamylated hemoglobin found in people with kidney failure, can also interfere.

**Q: How common is sickle cell trait?**
About 8 percent of African American babies in the United States are born with it, and about 30 percent of people in Ghana carry it. Carriers inherit the variant from one parent and usually have no symptoms.