Self-monitoring of blood glucose (SMBG) had no effect on glycemic control or health-related quality of life (QOL) in patients with type 2, non-insulin-treated diabetes, according to a randomized controlled trial (RCT) conducted in 15 primary care practices. The 450 participants were assigned to one of three interventions: no SMBG, once-daily SMBG, or once-daily SMBG with enhanced patient feedback (e.g., automatic tailored messages delivered through the meter). After one year, HbA1c levels were similar among groups.
The study was published in the July JAMA Internal Medicine and summarized in the July ACP Diabetes Monthly. The following commentary by Harvey J. Murff, MD, MPH, was published in the ACP Journal Club section of the Oct. 17 Annals of Internal Medicine.
Evidence-based guidelines support SMBG in patients with type 1 diabetes to improve glycemic control. In patients with type 2 diabetes who are not receiving insulin, however, the results of RCTs have been mixed and suggest a small but transient improvement in HbA1c levels with SMBG. Given patient discomfort and costs related to routine SMBG, additional evidence is needed to determine whether the benefits of SMBG are greater than these inconveniences.
The pragmatic Monitor Trial by Young and colleagues adds to the evidence about routine use of SMBG for all patients with type 2 diabetes. The trial was adequately powered and had minimal loss to follow-up, lending support to the validity of the study's null conclusions.
At first glance, the results of the Monitor Trial seem to run counter to the idea that SMBG should lead to more patient engagement and better glycemic control. At baseline, >85% of study participants had been receiving care for diabetes for >1 year, 75% were already performing SMBG, and mean HbA1c level was about 7.5%. Thus, the trial may best inform clinical decisions related to SMBG testing in patients who have a long-term diagnosis, stable glycemic control, and wish to stop SMBG.
The results do not apply to patients who have poorer glycemic control and require therapy intensification. In addition, the trial evaluated SMBG as a once-a-day test. Whether SMBG might improve glycemic control in patients particularly motivated to use the information to make lifestyle changes is unknown.
For clinicians caring for patients with type 2 diabetes, the results of the Monitor Trial provide reassurance that for certain patients, overall glycemic control will not be influenced by SMBG.