Epidemiologic Association between Inflammatory Bowel Diseases and Type 1 Diabetes Mellitus: a Meta-Analysis

Patients with inflammatory bowel diseases (IBD) are at high risk of developing several autoimmune diseases. However, the epidemiological connection between IBD and type 1 diabetes mellitus (T1DM) remains controversial. This meta-analysis aimed to determine the association between the two diseases.

A literature search was performed using Medline, Embase, and Central databases from inception to December 31, 2019. Studies evaluating the prevalence of T1DM in patients with IBD and controls were included. Statistical analysis was performed with a random effects model using the generic inverse variance method.

After the literature research, five cross-sectional studies and one case-control study met the inclusion criteria. A total of 45,103 participants with Crohn's disease (CD) and 76,046 with ulcerative colitis (UC) were included. The pooled odds ratios (ORs) of T1DM were 1.16 (confidence interval [95% CI]: 0.87-1.55) in patients with CD and 1.20 (95% CI: 0.90-1.59) in patients with UC compared with the control groups. Significant heterogeneity was observed (CD: I 2 =70% and UC: I 2 =80%) in the complete analysis. Subgroup analysis stratified by study region was performed. Recalculated results indicated a positive association between CD and TD1M in Northern Europe with an OR of 1.65 (95% CI: 1.43-1.90; I 2 =0%). Patients with UC in Israel were at a higher risk of developing T1DM with an OR of 1.70 (95% CI: 1.38-2.09; I 2 =0%).

The complete meta-analysis suggests no association between IBD and T1DM. However, the subgroup analysis indicated that patients with CD or UC from specific regions may be at a higher risk of developing T1DM than those without IBD.