Type 2 diabetes mellitus (T2DM) and rheumatoid arthritis (RA) are both chronic diseases. Although the link between metabolic abnormalities and dysregulated inflammation has received much attention, it is not known whether T2DM can be a risk for the development of RA. Also, observational studies have the disadvantage that the possibility of confounding factors, such as environmental factors, cannot be ruled out. Therefore, the current study performed the mendelian randomization (MR) analysis using recent large-scale genome-wide association studies datasets of T2DM and RA separately European and Asian ancestries. As a result, T2DM had an inverse causal effect on the risk of RA. This study proposed a novel hypothesis that a protective effect of T2DM for the risk of RA.

2型糖尿病（T2DM）和类风湿关节炎（RA）均为慢性疾病。尽管新陈代谢异常与炎症失调之间的联系备受关注，但尚不清楚T2DM是否可能成为RA发展的风险。而且，观察研究的缺点是不能排除诸如环境因素之类的混杂因素的可能性。因此，本研究使用欧洲和亚洲祖先分别进行的T2DM和RA的大规模大规模全基因组关联研究数据集进行了孟德尔随机分析（MR）。结果，T2DM对RA风险具有负因果关系。这项研究提出了一个新的假设，即T2DM对RA风险具有保护作用。