Inflammatory Bowel Diseases Increase Risk of Type 2 Diabetes in a Nationwide Cohort Study.

BACKGROUND & AIMS: The intestine regulates glucose homeostasis, but it is not clear whether chronic intestinal inflammation affects risk for type 2 diabetes. We investigated the long-term risk of type 2 diabetes in patients with inflammatory bowel diseases (IBD) in a nationwide cohort study in Denmark.

METHODS

In a nationwide population-based cohort of 6,028,844 persons in Denmark, we compared data from individuals with a diagnosis of IBD (Crohn's disease [CD] or ulcerative colitis UC]) with data from individuals from the general population from 1977 through 2014. Persons with type 2 diabetes were identified in the National Patient Register. Risk is presented as standardized incidence ratios (SIR) with 95% CIs.

RESULTS

During 736,072 person-years of follow-up, 3436 patients with IBD developed type 2 diabetes vs 2224 expected (SIR, 1.54; 95% CI, 1.49-1.60). The risk was significantly increased in patients with UC (SIR, 1.54; 95% CI, 1.48-1.60), in patients with CD (SIR, 1.57; 95% CI, 1.47-1.67), in women (SIR, 1.51; 95% CI, 1.44-1.59), and in men (SIR, 1.57; 95% CI, 1.50-1.65). The risk was highest the first year after a diagnosis of IBD (SIR, 4.48; 95% CI, 4.16-4.83), but remained increased for 20 or more years following the diagnosis (SIR, 1.26; 95% CI, 1.16-1.38). The increased risk could not be accounted for by frequency of health care contacts or corticosteroid exposure. Patients who received a diagnosis of IBD from 2003 through 2014 (SIR, 1.79; 95% CI, 1.67-1.91) had a significantly higher risk of type 2 diabetes than patients who received a diagnosis of IBD from 1977 through 1988 (SIR, 1.47; 95% CI, 1.39-1.56) or 1989 through 2002 (SIR, 1.48; 95% CI, 1.41-1.56) (P < .001).

CONCLUSIONS

In a population-based cohort study, we found an increased risk of type 2 diabetes in patients with UC or CD, with highest risk estimates from 2003 through 2014, compared with earlier years. Studies are needed to determine the effects of IBD treatment on risk of type 2 diabetes.