Patients with inflammatory bowel disease (IBD) are at higher risk of developing type 2 diabetes, compared with the general population, according to a study conducted in Denmark.
The study, “Inflammatory Bowel Disease Increases Risk of Type 2 Diabetes in a Nationwide Cohort Study,” was published in Clinical Gastroenterology and Hepatology.
IBD comprises a group of autoimmune disorders, including Crohn’s disease (CD) and ulcerative colitis (UC), which causes inflammation that disrupts the function of the gastrointestinal tract.
Although the intestine plays an important role in regulating glucose (blood sugar) metabolism, it is unclear if bowel inflammation in CD or UC increases the risk of developing type 2 diabetes, a disorder in which blood sugar levels are too high.
In this study, a group of investigators in Denmark set out to compare the risk of type 2 diabetes in a large group of patients with CD or UC, compared with the general population.
To that end, they carried out a nationwide population-based cohort study that involved 6,028,844 residents of Denmark between 1977 and 2014, and who were identified through the Danish Civil Registration System.
Individuals who were diagnosed with CD or UC within this time period were all included in the study. People with type 2 diabetes were identified through the National Patient Register. All participants were followed until they developed type 2 diabetes, emigrated, or passed away, or until the end of the study period, whichever came first.
A total of 65,180 IBD patients (44,915 with UC and 20,265 with CD) were identified and eligible to be included in the study.
After a mean follow-up of 11.3 years, 3,436 IBD patients had developed type 2 diabetes. This number was much higher compared with the expected number of 2,224 cases, indicating that IBD patients had a 50% increase in the risk of developing type 2 diabetes compared to individuals from the general population.
Of note, the expected number of cases was calculated by investigators based on incidence rates observed among individuals from the general population with an added risk factor for IBD.
This increased risk for type 2 diabetes was found for patients with CD and UC, regardless of gender. In addition, the researchers found the risk tended to be higher during the first year after the patients’ IBD diagnosis, although it remained higher than what would be expected for 20 years or more following initial diagnosis.
This higher risk was not linked to the frequency of healthcare visits, or exposure to corticosteroids.
Moreover, the researchers discovered that IBD patients who were diagnosed between 2003 and 2014 were more likely to develop type 2 diabetes (SIR of 1.79), compared with those who were diagnosed earlier, between 1977 and 1988 (SIR of 1.47), or between 1989 and 2002 (SIR of 1.48). SIR (standardized incidence ratio) is calculated as the ratio between the number of observed cases and the number of expected cases; an SIR higher than 1 means the number of real cases is higher than what would be expected.
According to the authors, the increase in the number of IBD patients developing type 2 diabetes in recent years coincides with an increased use of tumor-necrosis-factor-alpha (TNF-alpha) inhibitors to treat IBD, suggesting a possible link between IBD medications and diabetes.
The investigators “found an increased risk of type 2 diabetes in patients with UC or CD. The risk was particularly high in patients diagnosed in the new millennium, hence warranting further investigations into the impact of IBD treatments on diabetes risk.”