I recently received the following question:
I am 41 years old and about 60 pounds overweight. I had a bad gallbladder and it was removed, along with a four inch benign cyst on my right adrenal gland. In the process of being checked by my OB, I received a diabetes diagnosis. I have thalassemia, which is a hemoglobin abnormality. I had gestational diabetes through my two pregnancies and my OB told me that the A1C will give a false result for me and I must instead have the total glycohemoglobin test. I received a result of 9.5 today. I have been testing every day with my meter for the past few days. My fasting sugar is always 130 or above but my 2 hour results are all around 115 which I understand to be a good result (for a diabetic?).
I guess my questions are:
1. Do you have any source information or know where I can get good information on the alternate test? It doesn’t seem to be available in any diabetes literature or online.
2. Do you have any thoughts as to whether my other body system issues could be impacting my blood sugar result? It seems to me with adrenal issues that my pancreatic function would be affected.
Some thoughts for you to chew on:
1) Re total glycohemoglobin vs A1C: “Total glycohemoglobin” is one of many confusing names used when measuring the stuff that is a combination of hemoglobin and glucose. Trouble is, there have been many combinations of hemoglobin and glucose that have been studied, including among others the following: hemoglobin A1a, hemoglobin A1b, HbA1c, hemoglobin A1 (the sum of hemoglobins A1a, b, and c), and total glycohemoglobin. In 2007, a statement of several diabetes organizations tried to clarify the name of the most important stuff, clinically speaking, in a document called the Consensus Statement on the Worldwide Standardization of the Hemoglobin A1C Measurement, from the American Diabetes Association, European Association for the Study of Diabetes, International Federation of Clinical Chemistry and Laboratory Medicine, and the International Diabetes Federation.
2) Concerning the usefulness of the total glycohemoglobin test compared to the A1C, one author comments that: “Other useful markers for diabetes control include total glycohemoglobin, which does not take into account the hemoglobin beta-chain and other blood-based glycated proteins such as fructosamine… While useful, these tests have not been as well validated as A1C. Although they have not been proven to reliably predict diabetes complications… they should also be useful for this purpose.” (Case Study: Potential Pitfalls of Using Hemoglobin A1c as the Sole Measure of Glycemic Control)
3) Thalassemia is well-known to affect some assays for A1C: see Falsely elevated hemoglobin A1c due to S-beta+-thalassemia interference in Bio-Rad Variant II Turbo HbA1c assay. Fortunately, thalassemia does not affect blood glucose levels, and some alternate assays to the usual A1C test are available. If your physician doesn't know which ones are available, he/she should ask the director of the lab that you are using.