Objective: To estimate the frequency of continuous glucose monitoring (CGM) use and change in hemoglobin A1c (HbA1c) compared to self-monitoring of blood glucose (SMBG) alone in adults with type 1 diabetes in a clinical practice setting.
Methods: We retrospectively identified 66 adult type 1 diabetes patients at the Barbara Davis Center for Diabetes (BDC) who first initiated CGM between 2006 and 2011 and 67 controls using SMBG. The frequency of CGM use was estimated from survey recall and defined as the mean number of days/month of CGM use during a maximum follow-up of 10 months. Change in HbA1c was calculated as the difference between the baseline value and the lowest follow-up value.
Results: The mean change in HbA1c for CGM users was -0.48% (95% confidence interval [CI]: -0.67, -0.28) and for SMBG users was -0.37% (95% CI: -0.56, -0.18). The between-group mean difference in change in HbA1c, adjusted for patient characteristics, was -0.11% (95% CI: -0.38, 0.16), whereas the subgroup with a baseline HbA1c ≥7.0% and users of CGM ≥21 days/month was -0.36% (95% CI: -0.78, 0.05). Nearly half (n = 32, 48%) used CGM <21 days/month. The reasons for low frequency of CGM use or discontinuation included sensor costs, frequency of alarms, inaccuracy, and discomfort.
Conclusions: These CGM data from clinical practice suggest a trend toward decreasing HbA1c for adults with type 1 diabetes, especially in patients with higher baseline HbA1c and higher frequency of CGM use. Future studies are needed to assess the use of CGM in larger populations of clinical practice adult type 1 diabetes patients.