1298-OR: CGM-Derived Disposition Index in Stage 1 Type 1 Diabetes (T1D)

Introduction and Objective: Monitoring of beta cell function in those with preclinical T1D relies on serial frequently sampled oral glucose tolerance tests (OGTT), which poses major challenges given the practical burden and expense of this test. Herein, we validated a fully CGM-derived disposition index (DICGM) - a proxy of beta cell function -computed against the gold-standard OGTT DI in a cohort of people with Stage 1 T1D. Methods: Participants with stage 1 T1D aged 12-45y wore a blinded CGM and had an OGTT at enrollment with repeat CGM wear 1-year later. Sensors were inserted 24hrs prior to the 3-hour OGTT, which measured glucose, insulin, and C-peptide over 10 time points. CGM profiles were matched to OGTT data via retrofitting. DICGM was computed using the retrofitted data and validated against the DI obtained from the oral minimal model (DIOMM), using plasma measures. Association between baselineDICGM and percent time140mg/dl (TA140) at 1Y was also explored. Results: 24 participants (19±8y) were enrolled, 20 completed all study procedures. Baseline DICGM was highly correlated with DIOMM (r=0.89, p0.001) (Fig1A) and agreement between measures was not impacted by extreme values (Fig1B). Baseline DICGM was associated with 1Y-TA140 (r=-0.59, p= 0.049). Conclusion: DI can be accurately estimated using CGM during an OGTT. DICGM predicts a 1Y clinically relevant outcome in people with Stage 1 disease. Disclosure H. Marchiori: None. M. Schiavon: Research Support; Current; Sanofi. E.M. Tichy: None. M.D. Alguard: None. M. DeSousa: None. S. Del Favero: Research Support; Current; Dexcom, Inc. Other - cession of IP rights; Current; Dexcom, Inc. J. Gaglia: Consultant; Current; Vertex Pharmaceuticals Incorporated, AstraZeneca, polTreg. Research Support; Current; Sanofi. Stock/Shareholder; Current; Vertex Pharmaceuticals Incorporated. J. Sherr: Other - research support, consultant, advisory board member; Current; Abbott Diabetes. Other - advisory board member, consultant; Current; Vertex Pharmaceuticals Incorporated. Consultant; Current; Ypsomed AG. Research Support; Current; Dexcom, Inc., JDRF, Provention Bio, Inc., National Institutes of Health. Other - research support, consultant, advisory board member; Current; Insulet Corporation, Medtronic. Research Support; Current; Sanofi. Advisory Panel; Current; sequel med tech. C. Dalla Man: Other - Webinar provider; Ended; Sanofi. Other - Joint research project; Current; Sanofi-Aventis Deutschland GmbH. A. Galderisi: Advisory Panel; Current; Sanofi. Advisory Panel; Ended; Novo Nordisk. Advisory Panel; Current; vTv Therapeutics. Funding BT1D 3-SRA-2022-1186-S-B