Overtesting in Stable Diabetes Leads To Overtreatment

Rozalina G. McCoy, M.D. Senior Associate Consultant Division of Primary Care Internal Medicine Assistant Professor of Medicine Mayo Clinic

Dr. McCoy

MedicalResearch.com Interview with:
Rozalina G. McCoy, M.D
Senior Associate Consultant
Division of Primary Care Internal Medicine
Assistant Professor of Medicine
Mayo Clinic

Medical Research: What is the background for this study? What are the main findings?

Dr. McCoy: Blood glucose monitoring is an integral component of managing diabetes.  Glycosylated hemoglobin (HbA1c) is a measure of average glycemia over approximately 3 months, and is used in routine clinical practice to monitor and adjust treatment with glucose-lowering medications.  However, monitoring and treatment protocols are not well defined by professional societies and regulatory bodies; while lower thresholds of testing frequencies are often discussed, the upper boundaries are rarely mentioned.  Most agree that for adult patients who are not using insulin, have stable glycemic control within the recommended targets, and have no history of severe hypoglycemia or hyperglycemia, checking once or twice a year should suffice. Yet in practice, there is a much higher prevalence of excess testing.  We believe that such over-testing results in redundancy and waste, adding unnecessary costs and burdens for patients and the health care system.

We therefore conducted a large retrospective study among 31,545 adults across the U.S. with stable and controlled type 2 diabetes who had HbA1c less than 7% without use of insulin and without documented severe hypoglycemia or hyperglycemia.  We found that 55% of patients had their HbA1c checked 3-4 times per year, and 6% had it checked 5 times a year or more.  Such excessive testing had additional harms as well – we found that excessive testing was associated with greater risk of treatment intensification despite the fact that all patients in the study already met glycemic targets by having HbA1c under 7%.  Indeed, treatment was intensified by addition of more glucose lowering drugs or insulin in 8.4% of patients (comprising 13%, 9%, and 7% of those tested 5 or more times per year; 3-4 times per year; and 1-2 times per year, respectively).

Medical Research: What should clinicians and patients take away from your report?

Dr. McCoy: Excessive testing of HbA1c is common even among stable controlled non-insulin requiring adults with type 2 diabetes who have no indications for intensive monitoring or intensive treatment. Excessive testing not only leads to waste, patient burden, and increased costs of care for a highly prevalent chronic disease affecting millions of individuals in the US and worldwide; it also has the potential for patient harm by giving rise to overtreatment.  While our study did not directly probe for incidence of hypoglycemia and other adverse drug events caused by such overtreatment, it is nonetheless concerning.  It is therefore important for providers and patients to engage in informed shared decision making about chronic disease management – they should be cognizant of why each test is performed, and question the risks and benefits of performing tests and prescribing treatments.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. McCoy: It is important to identify the reasons for over-testing, whether these are clinical uncertainty; misunderstanding the nature of the HbA1c test; desire for diagnostic or management thoroughness; fragmentation of care; or need to fulfill regulatory demands such as reporting of performance metrics.  It will be important to better characterize the potential implications of both over-testing and over-treatment on risk of hypoglycemia, cost of care, and other adverse outcomes of glucose-lowering therapy. Finally, I believe that HbA1c testing is just the “tip of the iceberg” of diabetes and other chronic disease management, as there is likely redundancy and waste in other commonly performed tests and procedures, each with their own set of risks and complications.


McCoy Rozalina G, Van Houten Holly K, RossJoseph S, Montori Victor M, Shah Nilay D.

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Rozalina G. McCoy, M.D (2015). Overtesting in Stable Diabetes Leads To Overtreatment

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