HELP ON DIABETES

MONITORING HBA1C

The hemoglobin H1c (HbA1c) test (also called the A1c test and glycohemoglobin test) estimates your glucose control over the previous three to four months and is used by your doctor to assess your overall glucose control. The HbA1c test mea­sures the amount of glucose that is attached to the hemoglobin (the oxygen-carrying protein) in the red blood cells. You can think of HbA1c as “sugar coating” on the hemoglobin—the higher the average glucose levels in your bloodstream, the higher the thickness of the sugar coating; that is, the more glucose is attached to the hemo­globin. Once the glucose is attached to the hemoglobin it stays there for the lifetime of the red cell, which is 120 days. Thus, measuring the amount of glucose attached to the hemoglobin in the blood gives you an estimate of the average glucose levels in the previous three to four months.

An average glucose increase of 35 mg/dl raises the HbA1c by 1 percent. Thus, if your average glucose levels are around 200, you will have an HbA1c of around 8. It has been shown that an elevated HbA1c is associated with increased risk for devel­opment of long-term diabetes complications. Most peo­ple with diabetes have an HbA1c between 6 and 7.

The reason for this cutoff is that with HbA1c levels in this range, you have a relatively low risk for severe long-term complications, whereas aiming for lower values would significantly increase the risk of hypoglycemic reactions.

Your doctor will measure the HbA1c level at least three to four times a year. If the value is above the recommended range, he or she will work with you to lower glucose levels further by making additional changes to your diet, exercise program, and diabetes medications.

HbA1c values will be artificially low if you have medical conditions that decrease the life of the red blood cells. Blood transfusions, gastrointestinal bleeding, and some blood cell conditions such as beta thalassemia major are examples of medical conditions in which the HbA1c levels do not reflect the blood glucose levels.

If the HbA1c value is not likely to be accurate, your doctor may instead do another test called fructosamine level. This measures the glucose attachment on other pro­teins in the blood (plasma proteins), the principal one being albumin. Your doctor will use the fructosamine level in the same way as the HbA1c test result: to guide therapy.