Glycosylated hemoglobin A
Glycosylated hemoglobin A, also referred to by it medically most important component Hb A1c, is blood test used to monitor the treatment of diabetes mellitus type 1 and diabetes mellitus type 2. Glycosylated hemoglobin A are "minor hemoglobin components of human erythrocytes designated A1a, A1b, and A1c. Hemoglobin A1c is most important since its sugar moiety is glucose covalently bound to the terminal amino acid of the beta chain. Since normal glycohemoglobin concentrations exclude marked blood glucose fluctuations over the preceding three to four weeks, the concentration of glycosylated hemoglobin A is a more reliable index of the blood sugar average over a long period of time."
The following table helps convert Hb A1c values to average daily blood glucose levels.
- 5% = 97 mg/dL
- 6% = 126 mg/dL (6.99 mmol/L)
- 7% = 154 mg/dL (8.54 mmol/L)
- 8% = 183 mg/dL (10.16 mmol/L)
- 9% = 212 mg/dL (11.77 mmol/L)
- 10% = 240 mg/dL
- 11% = 269 mg/dL
- 12% = 298 mg/dL
For each 1% change in HbA1c approximates a 30 mg/dL (2 mmol/L) change in the average daily glucose.
There is approximately 1 mmol/L between the fasting and postprandial glucose levels in treated diabetics. This difference may be as high as 5 mmol/L difference in untreated diabetics (in the UGDP trial).
Elevated hemoglobin A1c independently predicts outcome, even among patients without diabetes.
- Anonymous (2015), Glycosylated hemoglobin A (English). Medical Subject Headings. U.S. National Library of Medicine.
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- NEJM 2010 Glycated Hemoglobin, Diabetes, and Cardiovascular Risk in Nondiabetic Adults