How long does it take to see a change in the A1C test or eAG?

With the A1C test or eAG, it takes about 2 to 3 months to see all the results of an improvement (or worsening) in blood glucose. This is why there’s really no need to have the test more often than every 3 months. However, if you are newly diagnosed and may have been far out of range for a while, you may want to have your A1C measured every 2 weeks at first. Significant changes in blood glucose can be seen within 2 weeks. Or, for someone who is pregnant and seeking very tight glucose levels, A1C may be measured every month or two to make sure that the treatment plan is getting results.