Glycohemoglobin is a blood test that checks the amount of sugar (glucose) bound to hemoglobin. Only a small percentage of hemoglobin in the blood (4% to 6%) has glucose bound to it. People with diabetes or other conditions that increase the blood glucose levels have more glycohemoglobin.
The glycohemoglobin A1c blood test checks the long-term control of blood glucose levels in people with diabetes. Most doctors think the glycohemoglobin A1c level is the best way to check how well a person is controlling diabetes.
Its concentration is measured by means of analysis of a blood sample drawn from the vein in the arm.
Purpose of the Blood test
This blood test is done to check evolution of treatment for diabetes.
A home blood glucose test measures the level of blood glucose only at that moment. Blood glucose levels change during the day due to diet, exercise, and the level of insulin in the blood.
It is useful for a diabetic to have information about the long-term control of sugar levels. The glycohemoglobin test is one blood sample every 3 to 4 months, and the test does not change with any recent changes in medicines, diet or exercise.
Glucose binds to hemoglobin in red blood cells at steady rate. Since red blood cells last 3 to 4 months, the glycohemoglobin A1c test shows how much glucose is in plasma part of blood. This test shows how well diabetes has been controlled in the last 2 to 3 months and whether diabetes medicine needs to be changed.
The A1c level can also help doctors see how big your risk is of developing problems from diabetes, such as kidney failure, vision problems, and leg or foot numbness. The lower A1c level, the lower chance for problems.
Blood test Reference range values
- Adults: 4.5%-5.7%
- Children below 6 years old 7.5-8.5%
- Children ages 6-12 years old < 8%
- Teens ages 13-19 years old <7.5%
Total glycohemoglobin: 5.3%-7.5%
A glycohemoglobin A1c level above 8% means that diabetes has been poorly controlled over the last 2 to 3 months.
Some medical conditions can increase A1c levels, but the results may still be within normal level. Conditions include Cushing's syndrome, pheochromocytoma, and polycystic ovary syndrome (PCOS).