2115-P: Change in Bone Mineral Density (BMD) over 12 Months in Youth with Type 1 Diabetes (T1D)

Introduction and Objective: Previous reports show lower BMD in youth with T1D compared with pediatric reference data, yet longitudinal data on BMD remain limited. This study evaluated BMD changes over 12 months and factors affecting BMD change. Methods: Youth (N=115) with T1D aged 8-17 yrs underwent total body less head BMD assessment at 0 and 12 months. Anthropometrics, pubertal status, T1D-related variables, 25-hydroxyvitamin D (25OHD), and weight-bearing activity were collected at both time points. BMD z-scores were categorized as decreased, unchanged, or increased (±0.1 cutoff). Results: Mean baseline age was 12.9±2.5 yrs, T1D duration 6.1±3.2 yrs. Baseline and 12-month BMD z-scores were -0.29±1.03 and -0.13±1.06; BMI z-scores 0.67±0.82 and 0.67±0.83; A1c 8.1±1.1% and 8.4±1.1%; time in range (TIR) 48.6±16.8% and 48.4±17.1%; 25OHD 29.1±8.5 and 30.8±10.8 ng/mL; and energy expenditure from high-impact weight-bearing activities (EE) 207.0±363.7 and 157.2±281.2 kcal/day. Over 12 months, 63 youth (55%) had increased BMD z-score, 19 (17%) had no change, and 33 (29%) had decreased BMD z-score. Age differed across BMD change groups (11.8, 12.8, and 13.5 yrs for decreased, no change, and increased, respectively; p = .004). BMI z-score differed across BMD change groups at baseline (0.41, 0.54, and 0.84, p = .04) and 12 months (0.44, 0.61, and 0.87; p = .02), for decreased, no change, and increased, respectively. Pubertal status differed across BMD change groups (p = .003); decreased BMD group had higher proportion of pre-pubertal youth versus no-change group (58% vs 26%, p = .01) and increased group (58% vs 22%, p = .001). Higher EE was associated with increasing BMD z-score (p = .05). There were no associations of change in BMD z-score with A1c, TIR, or 25OHD. Conclusion: Over 12 months, increase change in BMD z-score in youth with T1D were associated with older age, higher BMI z-score, more advanced pubertal status, and higher EE from high-impact weight-bearing activity. The absence of glycemic and 25OHD effects on BMD warrants further study with longer follow-up. Disclosure N. Tantivit: None. L. Volkening: None. L.J. Tinsley: None. L.M. Laffel: Other - Travel support for scientific presentations; Ended; Boehringer Ingelheim International GmbH. Other - DSMB Chair; Ended; Janssen Pharmaceuticals, Inc. Consultant; Current; Dexcom, Inc. Advisory Panel; Current; Medtronic, Sequel, Tandem Diabetes Care, Inc. Consultant; Current; Roche Diabetes Care, Sinocare. Advisory Panel; Ended; Sanofi. Advisory Panel; Current; MannKind Corporation.