Type 2 Diabetes Mellitus in Inflammatory Bowel Disease Patients: A Case–Control Study Through a Long Follow-Up Period

<b>Background/Objectives:</b> The characterization of patients with inflammatory bowel disease (IBD) and type 2 diabetes mellitus (T2DM) as a new group has not been well detailed. This study aimed to evaluate the impact of T2DM on IBD progression and analyze the prevalence of steatotic liver disease and liver damage in these patients. <b>Methods:</b> Through a retrospective case-control study, we compared severe IBD occurrence in patients with both IBD-T2DM (cases) versus those with IBD alone (controls). Among 1047 medical records, 79 IBD-T2DM patients were selected and compared to 308 controls in a 1:4 ratio. Severe IBD was defined by variables such as surgery, target therapy, corticosteroid use, and hospitalization. Liver damage was assessed using Fib-4 (>1.3), and hepatic steatosis was evaluated by imaging. <b>Results:</b> There was no significant difference in severe disease rates (59.5% vs. 59.7%; <i>p</i> = 0.97). IBD-T2DM patients had higher rates of hepatic steatosis (62.9% vs. 27.2%; <i>p</i> < 0.0001) and liver damage (55.4% vs. 26.6%; <i>p</i> < 0.0001). IBD-T2DM patients used more corticosteroids (<i>p</i> < 0.0001) and fewer anti-TNF-alpha drugs (<i>p</i> = 0.007). The median age at diagnosis was higher in IBD-T2DM patients (48 vs. 32; <i>p</i> < 0.0001). In Crohn's disease, 24.3% of IBD-T2DM patients had exclusive colonic involvement compared to 5% in the IBD-only group (<i>p</i> = 0.003). <b>Conclusions:</b> T2DM was not associated with worse IBD progression, but was linked to increased liver steatosis and damage. Differences such as age of onset, colonic involvement, and liver damage suggest that IBD-T2DM patients could configure a special population worthy of further studies.