Poor glycemic control is associated with impaired bone accrual in the year following a diagnosis of type 1 diabetes.

CONTEXT: Type 1 diabetes (T1D) is associated with an increased fracture risk across the life course. The effects on bone accrual early in the disease are unknown. OBJECTIVE: To characterize changes in bone density and structure over the year following diagnosis of T1D and to identify contributors to impaired bone accrual. DESIGN: Prospective cohort study. SETTING: Academic children's hospital. PARTICIPANTS: Thirty-six children, ages 7 to 17 years, enrolled at diagnosis of T1D. OUTCOMES: Whole body and regional dual-energy X-ray absorptiometry and tibia peripheral quantitative computed tomography obtained at baseline and 12 months. The primary outcome was bone accrual assessed by bone mineral content (BMC) and areal bone mineral density (aBMD) velocity z score. RESULTS: Participants had low total body less head (TBLH) BMC (z = -0.46 ± 0.76), femoral neck aBMD (z = -0.57 ± 0.99), and tibia cortical volumetric BMD (z = -0.44 ± 1.11) at diagnosis, compared with reference data, P < 0.05. TBLH BMC velocity in the year following diagnosis was lower in participants with poor (hemoglobin A1c ≥7.5%) vs good (hemoglobin A1c <7.5%) glycemic control at 12 months, z = -0.36 ± 0.84 vs 0.58 ± 0.71, P = 0.003. TBLH BMC velocity was correlated with gains in tibia cortical area (R = 0.71, P = 0.003) and periosteal circumference (R = 0.67, P = 0.007) z scores in participants with good, but not poor control. CONCLUSIONS: Our results suggest that the adverse effects of T1D on BMD develop early in the disease. Bone accrual following diagnosis was impaired in participants with poor glycemic control and appeared to be mediated by diminished bone formation on the periosteal surface.