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., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: UZ Leuven received nonfinancial support for travel from Novo Nordisk, and Boehringer-Ingelheim for M.M.V. M.M.V. serves or has served on the speakers bureau for Dexcom—financial compensation for these activities has been received by KU Leuven. KU Leuven received nonfinancial support for travel from Medtronic, and financial support for travel from Roche for S.C. C.D.B. reports consulting fees and honoraria for speaking for Abbott, AstraZeneca, Boehringer-Ingelheim, A. Menarini Diagnostics, Eli Lilly, Medtronic, Novo Nordisk, and Roche. R.H. serves or has served on the advisory panel for Merck Sharp and Dohme, Boehringer-Ingelheim, and Eli Lilly. L.V.H. reports consulting fees and honoraria for speaking for Abbott, AstraZeneca, Boehringer-Ingelheim, Eli Lilly, Medtronic, Merck Sharp and Dohme, Novo Nordisk, and Sanofi-Aventis. G.V. serves or has served on the advisory panel for Merck Sharp and Dohme, Boehringer-Ingelheim, and Eli Lilly. G.V. reports consulting fees and honoraria for speaking from Merck Sharp and Dohme, Boehringer-Ingelheim, AstraZeneca, Sanofi-Aventis, Novo Nordisk, and Eli Lilly. E.D. has served on the advisory panel for Novo Nordisk. E.D. reports speaking fees from Novo Nordisk, Boehringer-Ingelheim, Eli Lilly, and AstraZeneca. N.M. serves or has served on the advisory panel for Boehringer-Ingelheim. N.M. reports speaking fees from Merck Sharp and Dohme, Boehringer-Ingelheim, AstraZeneca, Sanofi-Aventis, Novo Nordisk, and Eli Lilly. C.V. reports consulting and speaking fees from Medtronic, Boehringer-Ingelheim, AstraZeneca, and Sanofi-Aventis. F.N. reports consulting fees and honoraria for speaking from Abbott, AstraZeneca, Boehringer-Ingelheim, Eli Lilly, Johnson and Johnson, Medtronic, Merck Sharp and Dohme, Novo Nordisk, Roche, and Sanofi-Aventis. C.M. serves or has served on the advisory panel for Novo Nordisk, Sanofi-Aventis, Merck Sharp and Dohme, Eli Lilly, Novartis, AstraZeneca, Boehringer-Ingelheim, Roche, Medtronic, ActoBio Therapeutics, Pfizer, and Zealand Pharma. Financial compensation for these activities has been received by KU Leuven; KU Leuven has received research support for C.M. from Medtronic, Novo Nordisk, Sanofi-Aventis, Merck Sharp and Dohme, Eli Lilly, Roche, Abbott, ActoBio Therapeutics, and Novartis; C.M. serves or has served on the speakers bureau for Novo Nordisk, Sanofi-Aventis, Merck Sharp and Dohme, Eli Lilly, Boehringer-Ingelheim, AstraZeneca, and Novartis. Financial compensation for these activities has been received by KU Leuven. P.G. serves or has served on the advisory panel for Novo Nordisk, Sanofi-Aventis, Boehringer-Ingelheim, Janssen Pharmaceuticals, Roche, Medtronic, and Bayer. Financial compensation for these activities has been received by KU Leuven. P.G. serves or has served on the speakers bureau for Merck Sharp and Dohme, Boehringer-Ingelheim, Bayer, Medtronic, Insulet, Novo Nordisk, Abbott, Roche, and Dexcom. Financial compensation for these activities has been received by KU Leuven. KU Leuven received nonfinancial support for travel from Sanofi-Aventis, A. Menarini Diagnostics, Medtronic, and Roche for P.G. All disclosures were unrelated to the present work. S.F., T.M., and B.K. have nothing to disclose.