Over-testing HbA1c in type 2 diabetics
 Image credit: jarun011

New research indicates that some type 2 diabetics might be having their disease control tested too often. A Mayo Clinic study that examined a national cohort of more than 31,000 nonpregnant adults with controlled noninsulin-treated Type 2 diabetes determined that up to 60% of these individuals’ hemoglobin A1c levels (HbA1c) were tested more often than warranted, and that this excessive testing could lead to overtreatment.

No specific evidence suggests that overtesting causes harm, and clinical practice guidelines have never recommended minimum HbA1C testing. “Yet, among patients with stable and controlled disease, more frequent HbA1c testing might not benefit the patient, but would contribute to their treatment burden, resource use, and healthcare costs. Potential effects on overtreatment and resultant hypoglycemia, however, are not known,” the researchers noted in the study, which was published in BMJ (formerly the British Medical Journal).

To determine whether excessive testing was taking place, researchers conducted a retrospective data analysis of 31,545 commercially insured patients with diabetes who had had two consecutive HbA1c test readings below 7.0% within a 24-month period from 2001 to 2013. The authors excluded patients with type 1 diabetes, gestational diabetes, non-clinical diabetes, and secondary diabetes.

Overall, the researchers estimate that overtesting took place in more than 60% of these patients with otherwise stable type 2 diabetes. “Frequent” testing took place in 55% of these patients, meaning they got tested at least 3 or 4 times annually, despite maintaining an acceptable HbA1c level. In 6% of the patients, testing was deemed as “excessive” by the researchers, meaning they had at least five HbA1c tests per year or that the tests were taken less than 3 months apart. Clinical practice guidelines for HbA1C range from less than 6.5%, 7.0%, or 8.0%, with testing frequency up to twice per year or 6 or more months apart.

“We also identified a direct association between excessive testing and likelihood of treatment intensification that, in the context of HbA1c being already less than 7%, is concerning for overtreatment,” the authors explained. More than 8% of the patients who had maintained good glycemic control over their diabetes received intensive regimens that involved insulin or glucose-lowering drugs.

Such practices are wasteful and lead to inappropriate treatment in patients, the researchers indicated.

One interesting finding is excessive testing seemed to drop in the later years of this study. Compared to 2001-2002, rates were 46% lower in 2011. The U.S. National Quality Forum’s designation of unnecessary lab tests as one of nine areas of inappropriate or wasteful care in 2008 might explain this drop in overtesting.

Excessive testing takes place for a number of reasons, according to the study’s lead investigator, Rozalina McCoy, MD, a Mayo Clinic primary care physician and endocrinologist.

“Potential reasons for more frequent testing include clinical uncertainty; misunderstanding of the nature of the test—that is, not realizing that HbA1c represents a three-month average of glycemic control; or a desire for diagnostic and management thoroughness," said McCoy in a statement. Miscommunication among a patient’s multiple providers (fragmentation of care) or the pressure to meet public reporting of performance metrics might also lead to overtesting.

“My colleagues and I recognize we still have work to do. And, we hope that these findings will help inform decision-making for health care providers and patients everywhere,” McCoy said.