Risk of Developing Type 2 Diabetes in Individuals With a Psychiatric Disorder: A Nationwide Register-Based Cohort Study

OBJECTIVE Previous studies have investigated the incidence of type 2 diabetes in individuals with psychiatric disorders, but most studies have focused on a specific psychiatric disorder or a selected sample. More population-based studies are needed to determine these associations in representative samples. We therefore aimed to determine these associations in a nationwide, register-based dynamic cohort study. RESEARCH DESIGN AND METHODS We analyzed data from 5,005,612 adults living in Denmark between 1995 and 2018, without prior diabetes. We investigated 10 different categories of psychiatric disorders and a composite group with any psychiatric disorder. Individuals with a psychiatric disorder were compared with individuals without using multivariable-adjusted Poisson regression to estimate incidence rate ratios (IRR) of type 2 diabetes. We modeled age-specific incidence rates (IR) for individuals with and without the specific psychiatric disorder. All models were stratified by sex. RESULTS In total, 334,739 individuals developed type 2 diabetes during follow-up. For all investigated categories of psychiatric disorders, we found increased IR of type 2 diabetes for individuals with versus those without a psychiatric disorder (IRR: men, 1.47 [95% CI 1.45-1.50]; women, 1.65 [95% CI 1.62-1.68]). When we examined age-specific IR, the largest differences were found in the younger population (<50 years). CONCLUSIONS We found that the IR of type 2 diabetes was higher in individuals with a psychiatric disorder compared with individuals without a psychiatric disorder and particularly high in the younger people with a psychiatric disorder. New studies into the prevention and early detection of type 2 diabetes in these groups are warranted.