Association between diabetes mellitus and adhesive capsulitis of shoulder: a two-sample Mendelian randomization study

Objective The objective of this study was to investigate whether there is a causal relationship between diabetes mellitus and adhesive capsulitis of shoulder (ACS). Method A two-sample Mendelian randomization analysis was performed using publicly available genome-wide association study statistics. To determine whether diabetes was causally associated with adhesive capsulitis of shoulder, two datasets on diabetes among Europeans from the GWAS catalogue and adhesive capsulitis of shoulder among Europeans from FinnGen were extracted and the data were analyzed using inverse variance-weighted, MR Egger regression, weighted medians, weighted modes and simple modes. Sensitivity analysis and heterogeneity analysis were then used to assess the stability and reliability of the results. Results MR analysis showed causality between type 1 diabetes and ACS (odds ratio [OR] = 0.97, 95% CI = 0.85–1.11, P<0.05). No significant causal effect of type 2 diabetes on ACS (OR = 0.97, 95% CI = 0.95–1.13, P = 0.414). The Cochran Q test showed only a low level of heterogeneity between the type 1 diabetes and ACS data sets (Q = 106.0431, p = 0.045). Not heterogeneous between T2DM and ACS. Egger-intercept and funnel plots for data did not show multidirectional and asymmetry at the gene level. Conclusion The study was the first to find a negative association between type 1 diabetes and the risk of developing adhesive capsulitis of shoulder in European people. No cause-and-effect genetic link was found between type 2 diabetes and shoulder adhesive capsulitis.