Background: There is substantial evidence that adults with type 1 diabetes have reduced bone mineral density (BMD); however, findings in youth are inconsistent.

Purpose: To perform a systematic review and meta-analysis of BMD in youth with type 1 diabetes using multiple modalities: DXA, peripheral quantitative computed tomography (pQCT), and/or quantitative ultrasound (QUS).

Data sources: PubMed, Embase, Scopus, and Web of Science from 1 January 1990 to 31 December 2020, limited to humans, without language restriction.

Study selection: Inclusion criteria were as follows: cross-sectional or cohort studies that included BMD measured by DXA, pQCT, or QUS in youth (aged <20 years) with type 1 diabetes and matched control subjects.

Data extraction: We collected data for total body, lumbar spine, and femoral BMD (DXA); tibia, radius, and lumbar spine (pQCT); and phalanx and calcaneum (QUS). Weighted mean difference (WMD) or standardized mean difference was estimated and meta-regression was performed with age, diabetes duration, and HbA_1c as covariates.

Data synthesis: We identified 1,300 nonduplicate studies; 46 met the inclusion criteria, including 2,617 case and 3,851 control subjects. Mean ± SD age was 12.6 ± 2.3 years. Youth with type 1 diabetes had lower BMD: total body (WMD -0.04 g/cm², 95% CI -0.06 to -0.02; P = 0.0006), lumbar spine (-0.02 g/cm², -0.03 to -0.0; P = 0.01), femur (-0.04 g/cm², -0.05 to -0.03; P < 0.00001), tibial trabecular (-11.32 g/cm³, -17.33 to -5.30; P = 0.0002), radial trabecular (-0.91 g/cm³, -1.55 to -0.27; P = 0.005); phalangeal (-0.32 g/cm³, -0.38 to -0.25; P < 0.00001), and calcaneal (standardized mean difference -0.69 g/cm³, -1.11 to -0.26; P = 0.001). With use of meta-regression, total body BMD was associated with older age (coefficient -0.0063, -0.0095 to -0.0031; P = 0.002) but not with longer diabetes duration or HbA_1c.

Limitations: Meta-analysis was limited by the small number of studies with use of QUS and pQCT and by lack of use of BMD z scores in all studies.

Conclusions: Bone development is abnormal in youth with type 1 diabetes, assessed by multiple modalities. Routine assessment of BMD should be considered in all youth with type 1 diabetes.