December 3, 2004
A1c (Glycohemoglobin, HgbA1c), Hyperglycemia and DKA
Question from Coleman, Texas, USA:
My mother, who is 74 years old and wheelchair bound, has type 2 diabetes. She is on Avandia (1 per day) and Glipizide (3 per day). Her fasting, home monitored, blood sugar levels run around 200 to 250 mg/dl [11.1 to 13.9 mmol/L]. They rarely get below 180 mg/dl [10.0 mmol/L] no matter when she takes it. Home Health Nurses on their weekly visits obtain the approximate same blood sugar levels within 5 to 8 “points” when comparing their monitor with my mother’s, using both monitors at the same time. Fasting serum blood sugar levels run at the doctor’s office each month during a visit, will run in the 250 to 320 mg/dl [13.9 to 17.8 mmol/L] range. Her doctor is considering putting her on insulin injections.
Here’s the kicker: Her A1c test is always in the 6.0 range. How can her A1c test be in the normal range “every time” and her other blood sugar tests show her blood sugar so high? Her doctor admits that she doesn’t know why the A1c test and her other blood sugar tests show such a difference. We are wondering if your team might have an suggestion as to why.
Her current daily medications are Avandia, glipizide, Celebrex, hydrocodone/Apap, flexeril, Verapamil, nadolol, Effexor, Xanax, and Detrol LA.
Answer:
The A1c measurement depends on normal red blood cell survival duration. If the red blood cells are broken down prematurely or, if she has been transfused with blood, this will falsely lower the A1c. Other tests of glycemic control are available to your mother and her physician. These tests measure average glucose over two weeks, instead of three months. They are called the glycated albumin and the fructosamine tests. Finally, the A1c is a reflection of an average blood sugar over three months. It may be that sugars at other times of the day are okay. It would be helpful to monitor at other times during the day to see if the sugars are as high as they are in the morning.
JTL
