HbA1C Tests

The technology of measuring blood glucose (sugar) has gone through several changes in the last few years.  Blood meters today are not only more accurate, but also very easy to use.  There is no reason a diabetic shouldn't be checking blood sugar regularly.
What are you actually measuring when you prick your finger?  Some home meters measure whole blood, while others measure blood plasma.  You need to know what your blood meter measures.  They are both pretty accurate, they just measure blood differently.
Why do home blood sugar readings differ from lab readings?  If your meter measures whole blood, test results will be lower than plasma readings; all labs test blood plasma.  Plasma is the liquid part of blood, minus its cells.  In the lab, whole blood is placed in a tube and separated by a whirling process that forces the blood cells to the bottom, leaving blood plasma above the cells.  When testing for blood plasma, the red blood cells are removed before glucose is measured.
Home meters and lab equipment are usually calibrated to measure in different ways and will give different results.  Home meters are considered accurate if they fall within a certain percent of an accepted reference result - usually a lab result.  For example, if you have a whole blood test result of 139 mg/dl, it would be equivalent to a plasma reading of about 156 mg/dl.  Ask your doctor, or the lab, what guidelines they follow.
Should the blood sample of your home meter come from your finger, arm, or does it make a difference?  It would be best to take it from the finger, but that should be your decision.  The finger is usually more accurate.  They are working on several other ways of taking blood tests, like infrared light through the forearm or finger or using a low-level electrical current to bring the blood up through the skin. 
The blood test you do at home measures the level of sugar in your blood only at the time of the test.  It is very important for you to take your daily tests, because they let you know if you need to eat something, not eat something, take more medication, take more insulin, or get more or less exercise.  Testing daily will allow you to better manage your blood glucose.
Hemoglobin is a protein molecule inside red blood cells that carries oxygen from the lungs to all cells and tissue of the body.  Like all proteins, hemoglobin can link up with glucose. Glycohemoglobin, or Hemoglobin A1C, is simply "Glycol," meaning sugar, and hemoglobin," meaning red blood cells. Sugar can attach itself to hemoglobin and remain attached for the life of the red blood cell.  When you run high blood sugar levels, more sugar has attached itself to the cells.  The HbA1C tests measures the amount of sugar attached.  The higher the value above normal, the more out of control your blood sugar is.  Even if your blood sugar goes down, your red blood cells still remember when the blood sugar was higher.  This memory will not be erased completely until all of the red blood cells that have the memory have died and are replaced with new cells that contain fresh hemoglobin.  Sound simple?  Your HbA1C is a weighted average, not a simple average.  A red blood cell lives about 120 days, but blood cells do not all die at one time; old blood cells are constantly dying, and new ones are being produced.  Old blood cells do not contribute much to the HbA1C test but your blood sugar levels over the past month will contribute close to half of the test result.  If your blood glucose levels are down during May, June, and July, but higher during August then blood tests from August would provide a higher HbA1C test result.
When your diabetes is poorly managed, the red blood cells age faster and more sugar adheres to the cells; blood can become thick and cause damage to every bodily system.  When high sugar prevents enough oxygen from getting through the body, smaller vessels and capillaries become clogged, leading to problems with circulation.
You need to be getting an HbA1C test every four months for the purpose of evaluating your progress.  Your doctor should give you the results of your test.  Ask what the normal range is at the lab your doctor uses.  On the HbA1C test, the number represents an approximate average of glucose readings.  I am going to give you an example.  If you want to know more about your HbA1C test result, talk to your doctor.
If you were a 7% on your HbA1C, your average blood glucose should be about 170.
Percentages:      6%      7%      8%     9%    10%    11%    12%
Blood glucose: 135     170      205    240     275     310     345
The glucose numbers will vary with each lab; it is best to go by the percentages.  Normal is 6% mg/dl or less; the diabetic goal is 7% mg/dl or less.  When it goes above 7% mg/dl, and especially if it stays there, you need to be concerned and work harder to get your diabetes under control.  There are too many complications you will have unless you , and only YOU, can control it - not your doctor!