EASD: Studies Link Depression and Type 2 Diabetes

AMSTERDAM, Sept. 21 -- Type 2 diabetes may be linked to mental health disorders, but age and gender may be contributing factors, according to two separate studies.
Symptoms of depression or psychological stress were associated with increased risk of type 2 diabetes in men, but not in women, Swedish researchers reported.
A team from Canada said surveillance data suggest that "people with diabetes had a higher prevalence of all mental illnesses compared with people without diabetes."
In particular, they noted, the rate of affective and anxiety disorders was more than 30% higher in people with diabetes who were younger than 50 (P<0.05).
The studies, presented at the meeting of the European Association for the Study of Diabetes here, add to a growing body of evidence linking depression and other mental disorders to diabetes risk.
For example: among nearly 5,500 men and women followed in the prospective Stockholm Diabetes Prevention Program, men with the highest level of depressive symptoms had a nearly four-fold risk for type 2 diabetes, and a nearly two-fold risk for a prediabetic state compared with the least depressed men, reported Claes-Göran Östenson, M.D., of the Karonlinska Institute, and colleagues.
"No association between depressive symptoms and type 2 diabetes was present in women in this study, although there was a weak association to prediabetes," the investigators noted.
This was true even though women had higher scores on a depression index than men-13.4 + 3.6 for women versus 11.2 + 3.3 for men.
The study enrolled 5,432 people from 1992 through 1998. Oral glucose tolerance tests were done at baseline and again eight to 10 years later. Just over half of the participants -- 51.9% -- had a family history of diabetes.
The investigators also measured depressive symptoms at baseline, asking whether patients had sleep difficulties, apathy, anxiety, depression, fatigue, and back or shoulder pain during the preceding 12 months.
Answers were scored using a four-point scale and, based on their answers, patients were divided into quartiles, with the lowest quartile representing no depressive symptoms and the highest quartile representing the highest symptom scores.
At follow-up, 111 men and 60 women who at baseline had normal glucose tolerance had developed type 2 diabetes, and an additional 255 men and 181 women had prediabetes.
The mean age-adjusted odds ratio for type 2 diabetes among men who had the highest depression scores was 3.6 (95% confidence interval 1.9 to 6.7) compared with a mean of 1.8 (95% CI, 1.0 to 3.4) for men whose depression scores were in the two middle quartiles.
The odds ratio for prediabetes among men in the highest quartile was 1.7 (95% CI, 1.2 to 2.5) compared with 1.0 (95% CI, 0.7 to 1.4) for the middle two quartiles.
In an analysis adjusted for potential confounders, including BMI, family history of diabetes, smoking, leisure time physical activity, and socio-economic position, the odds ratio for type 2 diabetes in men in the upper quartile was 2.6 (95% CI, 1.3 to 5.0) and in the middle two was 1.5 (95% CI, 0.8 to 2.9).
In women in the top quartile, the age-adjusted odds ratio for depressive symptoms was 0.9 (95% CI 0.4 to 1.7) and for the middle two it was 0.8 (95% CI 0.4 to 1.4).
For the prediabetic state in women there was a suggestion of an association with depressive symptoms, but it was weak, the authors noted, with an age-adjusted odds ratio of 1.8 (95% CI, 1.1 to 2.9) in the top quartile, and 1.6 (95% CI, 1.0-2.4) for upper and middle quartiles, respectively.
Furthermore, when they adjusted for all of the potential confounders, they found that the assocation between depressive symptoms and type 2 diabetes vanished altogether.
In the Canadian study, Lauren C. Brown, a Ph.D. candidate at the University of Alberta in Edmonton, and colleagues, analyzed surveillance data on affective disorders, anxiety disorders, and organic and non-organic psychoses among patients 20 and older in the province.
They used diagnostic codes and an algorithm from the National Diabetes Surveillance System (NDSS) to identify people with diabetes, and examined trends over time from 1996 through 2005 and average annual prevalence of mental illnesses for patients with and without diabetes. The rates were age-standardized using the 2001 Alberta population as the reference.
The researchers found that "people with diabetes had a higher prevalence of all mental illnesses compared with people without diabetes, and this finding was consistent over the examined time period."
People with diabetes also had a more than a two-fold higher prevalence of non-organic psychoses than people without diabetes (P<0.05), and the frequency of psychoses increased in the last five years of the study period.
Moreover, the increased risk of psychoses in diabetes was apparent across all ages (P<0.05).
Given the increased rate of mental illness in people with diabetes, "research should focus on strategies to minimize complications and mortality in this population with comorbidity," the authors wrote.
Asked whether the known metabolic effects of psychotropic medications, particularly atypical antipsychotics, might have been a potential confounder, Dr. Brown acknowledged that the investigators were unable to control for medication use.
The study by Dr. Östenson and colleagues was supported by the Stockholm County Council, Swedish Council of Working Life and Social Research, Novo Nordisk Scandinavia, and Glaxo Smithkline Sweden. The authors declared no conflicts of interest.
The study by Dr. Brown and colleagues was supported by Alberta Health and Wellness. Dr. Brown is supported by a grant from the Alberta Heritage Foundation for Medical Research. Primary source: European Association for the Study of Diabetes Annual Meeting
Source reference: Östengon C-G et al. "Depressive symptoms and risk of type 2 diabetes and prediabetes in a prospective study of middle-aged Swedish men and women." Abstract 0351, presented Sept. 20.