Comparison of Points in Range Measured by the Self-monitoring of Blood Glucose and Time in Range Measured by the Continuous Glucose Monitoring.

Usage of time in range (TIR), measured by continuous glucose monitoring (CGM), has become common as a new index of glycemic control. Therefore, we compared points in range (PIR), measured by the self-monitoring of blood glucose (SMBG), with TIR. In this prospective observational study, 43 patients with diabetes wore FreeStyle Libre Pro and conducted SMBG at the same time. Time above range (TAR), TIR, time below range (TBR) and points above range (PAR), PIR, points below range (PBR) were compared, respectively. The median PAR was 35.7%, while the median TAR was 20.8% for CGM. Conversely, the PIR was 64.3%, while the TIR was 74.9%; similarly, the PBR was 0%, while the TBR was 1.7%. A significant positive correlation was found between PIR and TIR (r = 0.784, P < 0.001). In the Bland-Altman analysis performed to assess the association between the two methods, PIR showed a -9.9% bias compared with TIR. PIR may be used in patients who find it difficult to use CGM as a substitute of TIR, however caution is needed when interpreting the data due to the difference between PIR and TIR.