Causal association between type 2 diabetes mellitus, inflammatory bowel disease and iron deficiency anemia: A multivariable Mendelian randomization Study

Abstract

Purpose To investigate the casual role of type 2 diabetes mellitus(T2DM) and inflammatory bowel disease (IBD) in iron deficiency anemia (IDA). Methods Univariable and multivariable Mendelian randomization (MR) analyses were conducted to evaluate the associations of T2DM, ulcerative colitis (UC) and Crohn's disease (CD) with risks for IDA. Results CD and T2DM were found to be associated with IDA in all three diseases. The ORs were 1.035(95% CI 1.006–1.064; p = 0.049) for CD and 1.086(95% CI 1.004–1.168; p = 0.022) for T2DM, respectively. Furthermore, when assessing CD and T2DM simultaneously using multivariable MR, both were found to be associated with an increased risk of IDA (OR 1.039, 95% CI 1.001–1.069, p = 0.012; OR 1.100, 95% CI 1.034–1.166, p = 0.005). But considering the effects of UC and CD in multivariable MR, only T2DM was causally associated with IDA (OR 1.104, 95% CI 1.037–1.171, p = 0.004). Conclusion Associations were found in the incidence of IDA and an increased risk of T2DM and CD, highlighting the importance of IDA prevention in patients with T2DM and CD.