Test may miss diabetes in some African-Americans
More than 200 scientists from around the world teamed up to study the genetics of hemoglobin A1c (HbA1c), or "glycated hemoglobin", a measurement used by clinicians to diagnose and monitor diabetes. The authors report that they have identified 60 genetic variants that influence HbA1c measurements, as well as the ability of this test to diagnose diabetes. The gene variants, including one that could lead to African Americans being underdiagnosed with T2D, are described in PLOS Medicine in a paper by James Meigs of Harvard Medical School, USA, and Inês Barroso of the Wellcome Trust Sanger Institute, UK, and colleagues.
Levels of HbA1c in a given person depend on both blood glucose levels and characteristics of that person's red blood cells. In the new work, researchers analyzed genetic variants associated with each of these factors, together with HbA1c levels in 160,000 people without diabetes from European, African, and Asian ancestry who had participated in 82 separate studies worldwide. 33,000 people were followed over time to determine whether they were later diagnosed with diabetes.
The team identified 60 genetic variants--42 new and 18 previously known--that impact a person's HbA1c levels. People who had more variants that affect HbA1c levels through effects on blood glucose levels were more likely, over time, to develop diabetes (odds ratio 1.05 per HbA1c-raising allele, P=3x10-29). However, people who had more variants that affected HbA1c through effects on red blood cells did not have an increased diabetes risk. The impact of genetic variants on HbA1c levels was larg Continue reading