Autoimmune diseases and risk of gestational diabetes mellitus: a Mendelian randomization study

Observational studies have reported that autoimmune diseases are associated with gestational diabetes mellitus (GDM), but the causality is unknown. The study aimed to evaluate the potential causal effect of autoimmune diseases on GDM.

A two-sample Mendelian randomization (MR) study was designed using the summary statistics of GDM (123,579 individuals) and three common autoimmune diseases, including inflammatory bowel disease (IBD, 59,957 individuals), rheumatoid arthritis (RA, 80,799 individuals) and systemic lupus erythematosus (SLE, 14,267 individuals), from the genome-wide association study (GWAS). The fixed-effects inverse variance weighted (IVW) was used to deduce the causal association between autoimmune diseases and GDM, and sensitivity analyses were further performed.

The inverse variance weighting (IVW) method showed that RA and SLE increased the risk of GDM (RA: OR = 1.076, 95%CI = 1.033-1.122, P = 4.649E-04; SLE: OR = 1.025, 95%CI = 1.001-1.049, P = 0.044). But there were no any associations of IBD with GDM (P > 0.05). No significant horizontal pleiotropy was found by MR Egger regression (IBD: P for intercept = 0.905; RA: P for intercept = 0.103; SLE = P for intercept = 0.608).

This two-sample MR study found that both SLE and RA are positively associated with the risk of GDM. Our findings provide help for the future prevention and treatment of GDM to reduce associated maternal and fetal complications. However, more research is needed to obviate the role of the GC and the HCQ to ensure this relationship is causal.