Self-monitoring doesn't improve control of type 2 diabetes

- Kenny Lin, MD, MPH

"Have you been checking your sugars?" I routinely ask this question at office visits involving a patient with type 2 diabetes, whether the patient is recently diagnosed or has been living with the disease for many years. However, the necessity of blood glucose self-monitoring in patients with type 2 diabetes not using insulin has been in doubt for several years.

A 2012 Cochrane for Clinicians published in AFP concluded that "self-monitoring of blood glucose does not improve health-related quality of life, general well-being, or patient satisfaction" (patient-oriented outcomes) and did not even result in lower hemoglobin A1C levels (a disease-oriented outcome) after 12 months. In their article "Top 20 Research Studies of 2012 for Primary Care Physicians," Drs. Mark Ebell and Roland Grad discussed a meta-analysis of individual patient data from 6 randomized trials that found self-monitoring improved A1C levels by a modest 0.25 percentage points after 6 and 12 months of use, with no differences observed in subgroups. Based on these findings, the Society of General Internal Medicine recommended against daily home glucose testing in patients not using insulin as part of the Choosing Wisely campaign.

Still, the relatively small number of participants in trials of glucose self-monitoring, and the persistent belief that it could be useful for some patients (e.g., recent type 2 diabetes diagnosis, medication nonadherence, changes in diet or exercise regimen), meant that many physicians have continued to encourage self-monitoring in clinical practice. In a 2016 consensus statement, the American College of Endocrinology stated that in patients with type 2 diabetes and low risk of hypoglycemia, "initial periodic structured glucose monitoring (e.g., at meals and bedtime) may be useful in helping patients understand effectiveness of medical nutrition therapy / lifestyle therapy."

In a recently published pragmatic trial conducted in 15 primary care practices in North Carolina, Dr. Laura Young and colleagues enrolled 450 patients with type 2 non-insulin-treated diabetes with A1C levels between 6.5% and 9.5% and randomized them to no self-monitoring, once-daily self-monitoring, or once-daily self-monitoring with automated, tailored patient feedback delivered via the glucose meter. Notably, about one-third of participants were using sulfonylureas at baseline. After 12 months, there were no significant differences in A1C levels, health-related quality of life, hypoglycemia frequency, health care utilization, or insulin initiation. This study provided further evidence that although glucose self-monitoring may make intuitive sense, it improves neither disease-oriented nor patient-oriented health outcomes in patients with type 2 diabetes not using insulin.