An international team of researchers has found that a genetic variant carried almost exclusively by African Americans significantly reduces the accuracy of the standard test for type 2 diabetes, the glycated haemoglobin or HbA1c test

The test measures the amount of glucose that is carried by the red blood cells over the previous two to three months. At least one copy of the variant in the G6PD gene is carried by around 11% of African Americans. This means that around 650,000 African Americans in the United States could have undiagnosed type 2 diabetes if tested with the HbA1c test alone. The results suggest screening for G6PD alongside the diagnostic test, or using other diagnostic tests in populations with African ancestry in order to improve diagnoses of type 2 diabetes.