Differences in the roles of types 1 and 2 diabetes in the susceptibility to the risk of fracture: a systematic review and meta-analysis.

BACKGROUND Diabetes mellitus (DM) causes excess risk of fracture at varied sites. Whereas, the difference between the roles of types 1 DM (T1DM) and 2 DM (T2DM) diabetes in the risk of fractures remains limited and inconclusive. We, therefore, conducted a meta-analysis to assess the differences for the associations of T1DM and T2DM with the risk of fractures. METHODS We systematically searched PubMed, Embase, and the Cochrane library for eligible studies until May 2021. The odds ratios (ORs) with 95% confidence intervals (CIs) were used to calculate the pooled effect estimates for the associations of T1DM and T2DM with the risk of fractures using the random-effects model. An indirect comparison results for the ratio of OR (ROR) with 95% CI were also applied to assess the difference between T1DM and T2DM with the risk of fractures. RESULTS Twenty-two cohort studies involving a total of 6,484,851 individuals were selected for meta-analysis. We noted that T1DM was associated with an increased risk of all fractures (OR: 1.72; 95% CI 1.36-2.19; P < 0.001), and fractures at the hip (OR: 4.01; 95% CI 2.90-5.54; P < 0.001), upper arm (OR: 2.20; 95% CI 1.61-3.00; P < 0.001), ankle (OR: 1.97; 95% CI 1.24-3.14; P = 0.004), and vertebrae (OR: 2.18; 95% CI 1.85-2.57; P < 0.001). Moreover, T2DM induced excess risk to all fractures (OR: 1.19; 95% CI 1.09-1.31; P < 0.001), including fractures at the hip (OR: 1.25; 95% CI 1.15-1.35; P < 0.001), upper arm (OR: 1.42; 95% CI 1.20-1.67; P < 0.001), and ankle (OR: 1.15; 95% CI 1.01-1.31; P = 0.029). Furthermore, we noted that T1DM versus T2DM was associated with greater risk to all fractures (ROR: 1.45; 95% CI 1.12-1.87; P = 0.005), including fractures at the hip (ROR: 3.21; 95% CI 2.30-4.48; P < 0.001), upper arm (ROR: 1.55; 95% CI 1.09-2.20; P = 0.015), and ankle (ROR: 1.71; 95% CI 1.06-2.78; P = 0.029). CONCLUSIONS This study found that T1DM caused an excess risk to all fractures, including fractures at the hip, upper arm, and ankle than T2DM. Further studies should therefore be conducted to directly compare the differences between T1DM and T2DM with the risk of fractures at various sites.