Background: The SWITCH PRO trial demonstrated increased time in range (TIR) with insulin degludec vs. insulin glargine U100 in basal insulin-treated type 2 diabetes (T2D). This post hoc analysis of SWITCH PRO evaluated correlation of change in TIR with change in A1C during the trial.Methods: Correlation between change in TIR (70-180 mg/dL) and change in A1C from baseline (BL) to end of Maintenance 1 in the full cohort or subgroups stratified by BL median A1C (<7.5% or ≥7.5%) was assessed using Spearman correlation coefficient (rs).Results: BL characteristics between subgroups were similar. A linear correlation between change in TIR and change in A1C was demonstrated (Figure) in the full (rs -0.400) and BL A1C ≥7.5% (rs -0.426) subgroups, but this was less apparent in the BL A1C <7.5% subgroup (rs -0.173) (interaction p = 0.07). Increase in TIR equated to the greatest decrease in A1C in the BL A1C ≥7.5% subgroup: a 5% increase in TIR corresponded to estimated decreases in A1C of -0.4%, -0.1% and -0.7% in full, BL A1C <7.5% and BL A1C ≥7.5% subgroups, respectively; and a 10% increase in TIR to estimated A1C decreases of -0.5%, -0.1% and -0.8%, respectively.Discussion: Change in TIR was associated with change in A1C in this basal insulin-treated population, with closer association at higher baseline A1C. Change in TIR may offer complementary insights to change in A1C in measuring response to therapy.View largeDownload slideView largeDownload slide DisclosureR. Goldenberg: Advisory Panel; Self; AstraZeneca, Boehringer Ingelheim (Canada) Ltd., Eli Lilly and Company, HLS Therapeutics Inc., Janssen Pharmaceuticals, Inc., Merck & Co., Inc., Novo Nordisk Canada Inc., Sanofi, Consultant; Self; AstraZeneca, Boehringer Ingelheim (Canada) Ltd., Eli Lilly and Company, HLS Therapeutics Inc., Janssen Pharmaceuticals, Inc., Merck & Co., Inc., Novo Nordisk Canada Inc., Sanofi, Research Support; Self; AstraZeneca, Boehringer Ingelheim (Canada) Ltd., Eli Lilly and Company, Janssen Pharmaceuticals, Inc., Merck & Co., Inc., Novo Nordisk Canada Inc., Sanofi, Speaker's Bureau; Self; Agora , Amgen Canada, AstraZeneca, Boehringer Ingelheim (Canada) Ltd., CCRN, CHRC, CMS Canada, CSEM, Eli Lilly and Company, EOCI , HLS Therapeutics Inc., Inceptus, Janssen Pharmaceuticals, Inc., liV Medical Education Agency, Master Clinician Alliance , Medplan, Merck & Co., Inc., Mylan N. V., Novo Nordisk Canada Inc., Sanofi, Servier Laboratories, STA Communications Inc., TKTWG, Valeant . V. R. Aroda: Consultant; Self; Applied Therapeutics, Duke, Novo Nordisk, Pfizer Inc., Sanofi, Employee; Spouse/Partner; Janssen , Merck , Research Support; Self; Applied Therapeutics, Eli Lilly and Company, Fractyl , Medpace, Medpace, Novo Nordisk, Premier , Sanofi, Stock/Shareholder; Spouse/Partner; Janssen, Merck. L. K. Billings: Advisory Panel; Self; Bayer Inc., Lilly Diabetes, Novo Nordisk, Sanofi. A. Meller donatsky: Employee; Self; Novo Nordisk A/S. M. Frederiksen: Employee; Self; Novo Nordisk A/S. D. C. Klonoff: Consultant; Self; EOFlow, Fractyl Laboratories, Inc., LifeCare, Inc., Novo Nordisk, Roche Diagnostic USA, Samsung, Thirdwayv, Employee; Self; DIabetes Technology Society. E. Parvaresh rizi: Employee; Self; Novo Nordisk. R. M. Bergenstal: Advisory Panel; Self; Abbott Diabetes, Eli Lilly and Company, Novo Nordisk, Onduo LLC., Roche , Sanofi, United Healthcare , Consultant; Self; Abbott Diabetes, Ascensia , Dexcom, Inc., Eli Lilly and Company, Hygieia, Johnson & Johnson, Medtronic, Novo Nordisk, Onduo LLC., Roche, Sanofi, United Healthcare, Other Relationship; Self; HealthPartners Institute, Research Support; Self; Abbott Diabetes, Dexcom, Inc., Eli Lilly and Company, Helmsley Charitable Trust, Hygieia, Johnson & Johnson, Medtronic, NIDDK, Novo Nordisk, Onduo LLC., Roche, Sanofi, United Healthcare.FundingNovo Nordisk A/S