Reevaluating the Association between Type 1 Diabetes and Polycystic Ovary Syndrome: Insights from Two-Sample Mendelian Randomization

Polycystic ovary syndrome (PCOS) is one of the most common heterogeneous endocrine disorders among women of reproductive age. PCOS and its related traits are frequently observed in women with type 1 diabetes (T1DM), but the exact association between T1DM and PCOS remains unclear. We conducted a two-sample Mendelian randomization (MR) study to explore the causal association between genetically predicted T1DM and PCOS risk in individuals of European ancestry. We selected 31 single nucleotide polymorphisms (SNPs) as instrumental variables (IVs) for T1DM (exposure data) and obtained outcome data from the newest and largest published genome-wide association study (GWAS) of Europeans, which includes 24840 participants to date. Our results demonstrate that strict T1DM (excluding T2DM) might not result in a higher risk of PCOS genetically in Europeans (odds ratio (OR) = 1.024, 95% confidence interval (CI) = 0.975–1.074, p = 0.347). Moreover, we did not observe heterogeneity or pleiotropy in our study. Our results indicate that T1DM itself might not explain the relatively high prevalence of PCOS in women; adequately powered studies are needed to explore the mechanisms behind the frequent association of PCOS with T1DM and its possible effect on the health of patients.