April 11, 2002
A1c (Glycohemoglobin, HgbA1c)
Question from Hattiesburg, Mississippi, USA:
I am a 44 year old who has had type�2 diabetes for six years, and I also have thalassemia minor diagnosed at age 11. Are my A1c lab values valid considering the decreased life span of my red blood cells?
You are correct in suggesting that your hemoglobin A1c result may not be accurate because of thalassemia minor. The decreased lifespan of the red blood cells may result in a falsely lower value, depending on the lab’s method. Other alternatives, such as fructosamine or glycated albumin can be used. They are not quite as good because they only reflect sugars over previous two weeks, in comparison to hemoglobin A1c that reflects blood sugars over the previous three months.
[Editor’s comment: Your physician should notify the lab of your double-diagnosis, so they can find a method to measure your A1c to assess your diabetes control without interference from the abnormal hemoglobin found in thal-minor. See Evaluation of HbA1c determination methods in patients with hemoglobinopathies Schnedl WJ, Krause R, Halwachs-Baumann G, Trinker M, Lipp RW, Krejs GJ., in Diabetes Care 2000 Mar;23(3):339-44