According to new research, people with psychiatric disorders often have to deal with another trouble: Higher rates of type 2 diabetes than the general population.

"Increased prevalence of type 2 diabetes among individuals with a psychiatric disorder suggests that these conditions have a shared vulnerability," the Danish researchers said.

In the study, the investigators searched four electronic databases of scientific papers. They found 32 reviews based on 245 studies that included people with 11 categories of psychiatric disorders: schizophrenia, bipolar disorder, depression, substance use disorder, anxiety disorder, eating disorder, intellectual disability, psychosis, sleep disorder, dementia and a mixed group with different types of disorders.

Type 2 diabetes was most common among people with a sleep disorder (40%), followed by those with binge eating disorder (21%), substance use disorder (16%), anxiety disorders (14%), bipolar disorder (11%) and psychosis (11%). People with an intellectual disability were least likely to have diabetes (8%), the findings showed.

The rate of type 2 diabetes in the general population is 6% to 9%, according to the study published Nov. 29 in the journal Diabetologia.

Many people with sleep disorders have other health problems, and it's likely that these conditions contribute to the high rate of diabetes in people with sleep disorders, said study author Nanna Lindekilde, from the department of psychology at the University of Southern Denmark.

The researchers also said the link between sleep disorders and diabetes "is likely to be bidirectional, with the sleep disorder raising the risk of developing diabetes, while diabetes, especially in combination with poor metabolic control, increasing the risk of developing sleep problems."

While their study found an overall increased risk of diabetes among people with psychiatric disorders, rates may vary depending on where they live and other factors, the authors noted.

"Better understanding of the observed differences in disease risk and the reasons behind them are still needed," the researchers concluded in a journal news release.