What causes elevated HbA1c despite normal fasting blood sugar?

Question

Hello doctor,

Five years before, I had been dealing with an issue related to ESR and HbA1c levels. My recent diabetes screening showed the following results:

Fasting blood sugar (FBS): 5.2 mmol/L (Normal).
Glucose 2H (OGTT): 5.9 mmol/L (Normal).
HbA1c: 5.7% (38.8 mmol/mol) (Prediabetes range).

I am concerned about why my HbA1c is in the prediabetes range while my FBS and OGTT results are within the normal range. Other relevant test results are as follows:

Lipid profile: Normal.
Kidney function: Normal.
Liver function: Normal.
ESR: 42 MM/HR (indicating inflammation).
Vitamin B12: 471 PG/ML.
TSH: 1.12 UIU/ML (Normal).

I would appreciate insights into why my HbA1c might be elevated while other glucose-related tests appear normal, as well as any considerations regarding the elevated ESR.

Kindly help.

Thank you.

Answer 1

Hello,

Welcome to icliniq.com.

I understand your concern.

Based on the information you provided, some possible reasons why HbA1c (hemoglobin A1c) is high while FBS (fasting blood sugar) and OGTT (oral glucose tolerance test) are normal could be due to a variety of factors such as diet, exercise, medication use, stress, and other medical conditions. HbA1c is a measure of average blood glucose levels over a three-month period, whereas FBS and OGTT are measures of blood glucose levels at a specific point in time. So, it is possible that your blood glucose has been elevated over the past few months, although it may have been normal at the time of the FBS and OGTT tests.

I hope this helps.

Feel free to contact me if you have any further queries.

Thank you.