Investigators from multiple institutions conducted a randomized controlled trial assessing the effect of continuous glucose monitoring (CGM) on glycemic control in adolescents and young adults with type 1 diabetes. Participants were 14–24 years old with a duration of diabetes of at least 1 year who had baseline hemoglobin A1c (HbA1c) levels ≥ 7.5% and < 11.0%. At enrollment, study participants were randomized to use CGM or continue with their regular finger stick blood glucose monitoring (BGM). The CGM system included a disposable sensor inserted under the skin that transmitted interstitial glucose levels every 5 minutes to a receiver or smartphone app; twice-daily finger stick glucose levels were required to calibrate the system.
Participants were enrolled in the study for 26 weeks. The primary outcome was change in HbA1c level between baseline and week 26. Differences between groups were assessed using longitudinal linear regression. Secondary outcomes included change in HbA1c at 13 weeks and achieving a HbA1c level in the target range (< 7.5% for those < 19 years old and < 7.0% for those ≥ 19 years old) at 26 weeks. Those in the BGM group wore a CGM device during weeks 24–26 (glucose levels were not provided to the participant). Various glycemic control metrics, including mean glucose, time in the target glucose range (70–180 mg/dL), and time with glucose > 180 mg/dL and < 70 mg/dL, for those in the BGM and CGM groups were compared using regression analyses.
A total of 153 participants were included in the study, with 74 randomized to CGM and 79 to the BGM group. The mean age of study participants was 17 years, and mean duration of diabetes was 9 years. Mean baseline HbA1c values were 8.9% for both groups. However, at 26 weeks, mean HbA1c values were 8.5% for those in the CGM group and 8.9% for those randomized to BGM (adjusted difference between groups −0.37%; 95% CI, −0.66%, −0.08%; P = .01). There was also a difference in change in HbA1c levels at 13 weeks between groups (mean values 8.4% and 8.9%, respectively, for the CGM and BGM groups; difference 0.50%; 95% CI, −0.79%, −0.21%; P < .001). At week 26, there was no difference between groups in percent of participants who met target HbA1c values (13% CGM, 10% BGM, P = .42). During CGM monitoring for both groups, those in the CGM group had significantly lower mean glucose levels (P = .003), longer time in the target glucose range (P < .001), and less time with glucose > 180 mg/dL (P = .007) or < 70 mg/dL (P = .02).
The authors conclude that use of CGM led to small but statistically significant improvements...