Glycosylated hemoglobin, also known as glycated hemoglobin, is a red blood cell that has absorbed free-floating glucose from the blood stream. Glucose, or sugar, binds to a protein called heme within the cells in a non-reversible process called glycation. A test showing the concentration of glycosylated hemoglobin may be done to determine the amount of sugar in the blood over the entire lifespan of a red blood cell, which is usually about 120 days. This information enables a physician to determine the average blood glucose levels over time of a person with diabetes.
All people have a percentage of glycosylated hemoglobin circulating in the bloodstream. The average person will show a concentration of four to five percent on test results. A person with diabetes will typically have a result that is greater than seven percent.
The test for glycosylated hemoglobin is called a diabetic control index, a hemoglobin A1c test, or an HbA1c measurement. Blood is drawn to measure a person’s glycosylated hemoglobin levels. The most common complaint after the test is bruising or tenderness at the draw site. Over-the-counter pain relievers and an ice pack on the area can help alleviate the pain and swelling.
Testing is recommended twice a year for people with well-regulated diabetes. People that do not have stable sugar levels may need to be tested up to four times a year. The test may also be ordered to confirm a diagnosis of diabetes.
Elevated concentrations of glycosylated hemoglobin can indicate the risk of future health complications from diabetes. More people with consistently high percentages of glycosylated hemoglobin experience damage to the small blood vessels in the body. This damage can lead to blindness and kidney disease. Some people have the sensation of numbness or pins and needles in the arms and legs because of diabetic neuropathy.
A common complication of diabetes is slow wound healing, especially on the extremities. High blood sugar levels can cause poor blood circulation throughout the body. Without adequate blood supply, tissue is unable to heal and may become infected and necrotize, or die off. Surgical debridement of the infected area or an amputation of the dying tissue may be necessary to prevent the spread of the infection.
Medication, a nutritious diet, and regular exercise can lower blood sugar levels and improve circulation over time. The decrease in the available sugar in the bloodstream will cause lowered glycosylated hemoglobin percentages. An accurate depiction of average blood sugar levels cannot be determined from the test within three months of a diet or exercise change.