From the Guidelines
You should not repeat the A1C test just two weeks after your previous test, as it is typically recommended to wait at least 3 months between tests to see the effects of any treatment changes or lifestyle modifications. The A1C test measures your average blood glucose levels over the past 2-3 months by checking the percentage of hemoglobin with attached glucose [ 1 ]. Since red blood cells live for about 120 days, getting another test so soon wouldn't show meaningful changes from your previous result of 8.0%.
Some key points to consider:
- The A1C test is subject to certain limitations, such as conditions that affect erythrocyte turnover (hemolysis, blood loss) and hemoglobin variants [ 1 ].
- For patients prone to glycemic variability, glycemic control is best judged by the combination of results of SMBG testing and the A1C [ 1 ].
- If you're concerned about your current blood sugar control, you might consider using a home glucose monitor for daily readings instead, as these provide immediate feedback on your glucose levels and can help you track patterns before your next scheduled A1C test.
It's also worth noting that the most recent guidelines from 2021 [ 1 ] do not provide a specific recommendation for the timing of repeat A1C tests, but they do emphasize the importance of confirming the diagnosis of diabetes with two abnormal test results. However, in the context of your question, the key consideration is the timing of the repeat test, and the 2008 guidelines [ 1 ] provide more relevant guidance on this topic.
In terms of alternative tests, you could consider using a home glucose monitor for daily readings, or discussing other options with your healthcare provider, such as a fructosamine test or a continuous glucose monitor [ 1 ]. However, the A1C test remains the most widely used and recommended test for assessing glycemic control in patients with diabetes.
From the Research
HbA1c Testing and Continuous Glucose Monitoring
- The HbA1c test is a measure of average blood glucose control over the past 2-3 months 2, 3, 4, 5, 6.
- It is not possible to "redo" an HbA1c test, as it measures average glucose control over a period of time, but it is possible to have another test done after a certain period of time has passed.
- Continuous glucose monitoring (CGM) can provide more detailed information about glucose levels and trends than HbA1c testing alone 3, 4, 5, 6.
Relationship Between HbA1c and Time in Hypoglycemia
- Studies have shown that lower HbA1c levels are associated with increased time spent in hypoglycemia (<3.9 mmol/L and <3.0 mmol/L) during both CGM and conventional therapy with self-monitoring of blood glucose (SMBG) 5.
- CGM is associated with less time spent in hypoglycemia than SMBG at a broad range of HbA1c levels 5.
Effects of Continuous Glucose Monitoring on HbA1c
- Real-time continuous glucose monitoring (rtCGM) has been shown to improve glycemic control in type 1 diabetes patients treated with continuous subcutaneous insulin infusion (CSII) or multiple daily insulin injection (MDI) therapy 2, 4, 6.
- rtCGM use is associated with meaningful improvements in HbA1c and reductions in health care utilization compared to SMBG use 6.
Testing Frequency
- The frequency of HbA1c testing depends on individual factors, such as the stability of glucose control and the presence of any complications 2, 3, 4, 5, 6.
- It is generally recommended to wait at least 2-3 months between HbA1c tests to allow for changes in glucose control to be reflected in the test results 2, 3, 4, 5, 6.