From Newry, Maine, USA:
Does the HbA1c test truly paint an accurate picture for type 1 diabetes since it is an average? Is it more useful for type 2 patients who may not have large swings in blood sugar levels?
Hemoglobin A1c tests are excellent in placing people's glycemic control in perspective. In any situation where there are lots of ups and downs, of course, they do not reflect this, only a running average, but most folks testing only a few times a day before meals and occasionally after meals, have A1c values that really do reflect their long terms risks for complications. We learned this supremely well in a multicentered study called the DCCT.
The A1c does not tell you what needs to change if the values are too high or too low, only what the running average represents. The closer the values toward the normal range -- approximately 4-6% in most lab systems, the lower the risks for complications but the higher the risk for severe episodes of hypoglycemia. So there must be some balance between the two extremes. Most of us aim for A1c values around 7% but always with a major caveat against having too many episodes of hypoglycemia.
In type 2 patients where there is less day to day variability, the excursion would be lower, but the average is still the average and still reflects long term complications. Coupled with frequent blood glucose monitoring, A1c testing is offered to our own patients about every four to six weeks just as we did in the DCCT. Some folks recommend A1c values only every three months, however. Comparing A1c values sequentially and working towards moving them closer to the normal range is a very important treatment goal for anyone with either type 1 or type 2 diabetes.
Original posting 12 Nov 2001
Posted to Blood Tests and Insulin Injections
Last Updated: Tuesday April 06, 2010 15:09:27
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