While blood glucose monitoring shows the level of glucose in the blood at a particular point in time, another test gives a more long-term view of blood glucose levels. Glucose molecules attach to hemoglobin, the protein in red blood cells that colors the blood and transports oxygen and carbon dioxide. Glucose attaches in amounts corresponding to the level of glucose in the blood. This permanent attachment lasts the life of the cell, usually about two to three months. Therefore, a measurement of this “glycosylated” hemoglobin — also called glycohemoglobin, or glycated hemoglobin, or hemoglobin A1c — gives the big picture of a person’s blood glucose levels over a couple of months.
What it’s used for
Measurement of glycohemoglobin provides a broad view of blood glucose control, one that is not skewed by a single meal or a day or two of irresponsible eating habits or, conversely, a day or two of very responsible eating. It gives the big picture, as opposed to the narrow snapshot of a blood glucose reading.
No preparation is necessary for this test.
Blood is taken from a vein and analyzed in a laboratory. The normal range depends on the specific test that is used.
Your doctor will discuss with you the results of your glycohemoglobin test and what they mean for diabetes management. If your glycohemoglobin is above the normal range, some adjustment may be needed in your diet and/or medications.
There are no risks to this test.
Call your doctor if
Call your doctor if you have any questions about what the findings of this test mean.
Most doctors test people with diabetes for glycohemoglobin levels two to four times a year. However, if you are having trouble controlling your levels, the test may be done more often.