Background: ALERTT1 showed that switching from intermittently scanned continuous glucose monitoring (isCGM) without alerts to real-time CGM (rtCGM) with alert functionality improved time in range (TIR; 70-180 mg/dL), glycated hemoglobin (HbA1c), time <54 mg/dL, and Hypoglycemia Fear Survey version II worry subscale (HFS-worry) score after six months in adults with type 1 diabetes (T1D). Moderator analyses aimed to identify certain subgroups that would benefit more from switching to rtCGM than others.
Methods: Post hoc analyses of ALERTT1 evaluated the impact of 14 baseline characteristics on the difference (delta) in mean TIR, HbA1c, time <54 mg/dL, and HFS-worry score at six months between rtCGM and isCGM. Therefore, the delta was allowed to depend on each of these variables by including interactions in the moderator analysis model. Analyses were performed separately for each variable; variables with P < .10 in the univariable analysis were combined into a single model.
Results: Univariable analyses showed no dependency of delta TIR, HbA1c, or time <54 mg/dL on variables other than CGM type. Only delta HFS-worry score depended on baseline HbA1c (P = .0059), indicating less worries with rtCGM in people with baseline HbA1c <6.5% or ≥8%. Given P < .10 for dependency of delta TIR on insulin therapy type (favoring multiple daily injections), baseline HbA1c, and baseline TIR, these variables were combined into a multivariable analysis; interactions were not statistically significant.
Conclusions: Except for HFS-worry score, no interactions between 14 baseline characteristics and the six-month intervention effect of rtCGM on TIR, HbA1c, or time <54 mg/dL were observed, supporting the conclusion of ALERTT1 that switching from isCGM without alerts to rtCGM with alert functionality is beneficial for a wide range of people with T1D.
Keywords: continuous glucose monitoring; intermittently scanned continuous glucose monitoring; moderator analysis; real-time continuous glucose monitoring; type 1 diabetes.