Monitoring the blood is very important. Even so, it only tells you what your blood sugar is at the moment a reading is taken. If you test your blood two times, four hours apart, you have only the starting point and ending point for your blood sugars; you dont know what took place in between. Your doctor can do a test to fill in the gap, combined with many, many other gaps. The test is called the Hemoglobin A1c, or Hgb A1c.
This is a very useful blood test, done by the laboratory, to see how you have been doing overall with respect to the blood sugars. Hemoglobin is a protein that stays in the blood for about 90 days and is easily measured. The glucose in your blood can attach chemically to any proteins present, and stay attached permanently. The amount that attaches to the protein depends on how high the blood glucose is. For example, if glucose is high, more of it attaches to the protein; if glucose is low, very little attaches. The glucose stays attached until the hemoglobin molecule is broken down naturally by the body. The amount of hemoglobin with glucose attached to it is measured and compared with the total amount of hemoglobin present. This indicates how high the blood glucose has been, at some time in the life of the hemoglobin. For instance, if your glucose was high one month ago, then more glucose would have attached to the hemoglobin molecule at that time, and this could still be measured now. Measuring the HgbA1c is a convenient way for your doctor to get more information about your glucose control, and to track your progress. It becomes easy to say, based on these results, whether overall glucose control is actually improving, or worsening. Excellent levels, for someone with diabetes, would be 7.0% (.070) or less of total hemoglobin having glucose attached. When your HgbA1c is good, you can be sure that your glucose levels have been good for a long time.