Mendelian Randomization Provides No Evidence for the Bidirectional Relationship between Type 2 Diabetes and Venous Thromboembolism in East Asians and African Americans

We were very interested to read the recent paper by Hu et al, which presented a Mendelian randomization (MR) study examining the relationship between 13 cardiovascular risk factors and venous thromboembolism (VTE) in European individuals.[ 1 ] They found no evidence of an association between type 2 diabetes (T2D) and VTE. Recently, a bidirectional MR analysis showed similar results in individuals of European ancestry, indicating no association between T2D and VTE in either direction.[ 2 ] Nevertheless, their finding was limited to individuals of European ancestry, potentially restricting its applicability to other ethnic groups. Epidemiological studies in admixed American populations have suggested patients with type 1 diabetes or T2D may have an increased risk of VTE.[ 3 ] [ 4 ] However, there are few studies specifically investigating the relationship between T2D and VTE in African Americans. In East Asia, a large-scale prospective study among Chinese individuals indicated a higher risk of VTE in patients with T2D compared with the general population, but a Japanese study found no such association between diabetes and pulmonary thromboembolism.[ 5 ] [ 6 ] Given these gaps and inconsistencies, particularly regarding African Americans and East Asians, we were motivated to further explore the bidirectional association between T2D and VTE among these ethnicities. Thus, we employed a bidirectional two-sample MR method to investigate the presence and direction of the association between T2D and VTE in East Asians and African Americans.