American Society for Clinical Pathology and American Society for Clinical Laboratory Science

View all recommendations from this society

November 7, 2022

Don’t repeat HbA1c testing in stable patients within 3 months of a previous result.

The lifespan of a HbA1c is approximately 90–120 days, and the full effects of a patient’s change in behavior, diet, or newly adjusted medications will not be fully appreciated until all previous HBA1C in circulation are replaced (~90 days). Therefore, testing at time intervals earlier than 3 months may not allow enough time to pass to reach the expected target by the clinician. Testing at 6-month intervals may be considered when glycemic targets are consistently achieved.

These items are provided solely for informational purposes and are not intended as a substitute for consultation with a medical professional. Patients with any specific questions about the items
on this list or their individual situation should consult their physician.

How The List Was Created

(1–4) The American Society for Clinical Pathology (ASCP) list of recommendations was developed under the leadership of the ASCP Effective Test Utilization Steering Committee. This committee is chaired by an ASCP Past President and is comprised of subject matter and test utilization experts across the fields of pathology and laboratory medicine. The committee considered a list of possible recommendations compiled as the result of a survey administered to Society members serving on ASCP’s many commissions, committees and councils. In addition, an announcement was made to ASCP’s Advisory Board seeking suggestions for possible recommendations to promote member involvement. The laboratory tests targeted in our recommendations were selected because they are tests that are performed frequently; there is evidence that the test either offers no benefit or is harmful; use of the test is costly and it does not provide higher quality care; and eliminating it or changing to another test is within the control of the clinician. Implementation of these recommendations will result in higher quality care, lower costs and a more effective use of our laboratory resources and personnel.

(5) This recommendation was developed under the leadership of ASCLS’s Choosing Wisely Committee and the ASCLS Board of Directors. The Committee examined numerous options based on evidence available. Subject matter experts from the ASCLS Scientific Assemblies reviewed, edited, and recommended approval of this recommendation, which was subsequently reviewed and approved by the ASCLS Board of Directors.


American Diabetes Association. Standards of medical care in diabetes–2007. Diabetes Care. 2007 Jan;30 Suppl 1:S4-S41. doi: 10.2337/dc07-S004. PMID: 17192377.

Driskell OJ, Holland D, Waldron JL, Ford C, Scargill JJ, Heald A, Tran M, Hanna FW, Jones PW, Pemberton RJ, Fryer AA. Reduced testing frequency for glycated hemoglobin, HbA1c, is associated with deteriorating diabetes control. Diabetes Care. 2014 Oct;37(10):2731-7. doi: 10.2337/dc14-0297. PMID: 25249670.

McCarter RJ, Hempe JM, Chalew SA. Mean blood glucose and biological variation have greater influence on HbA1c levels than glucose instability: an analysis of data from the Diabetes Control and Complications Trial. Diabetes Care. 2006 Feb;29(2):352-5. doi: 10.2337/diacare.29.02.06.dc05-1594. PMID: 16443886.