Depression can lead to diabetes

People with depression have a higher risk of developing the most common form of diabetes than others, according to a study that sheds light on the interplay between the two conditions.

The study published on Tuesday indicated that the relationship between type-2 diabetes, the form of the disease closely linked to obesity and sedentary lifestyle, may be a bit like a two-way highway. Not only can diabetes lead to depression, as has been well established, but depression can also lead to diabetes.

US researchers led by Dr Sherita Hill Golden of Johns Hopkins University School of Medicine in Baltimore tracked an ethnically diverse group of about 5,000 men and women between ages 45 to 84 for about three years.

They found that people with symptoms of depression were 42% more likely to develop diabetes by the end of the study than those without such symptoms. They also found that the more serious the symptoms, the higher the risk of diabetes. The researchers statistically accounted for factors including obesity, lack of physical activity and smoking, and found that the risk for diabetes was still 34% higher in patients with depression.

"When we looked at the people in our study who had elevated symptoms of depression, they were more likely to eat more calories, they exercised less, and they were more likely to be current smokers. And as a consequence, they were also more obese," Golden, whose study was published in the Journal of the American Medical Association, said in a telephone interview.

"And those are all known risk factors for type-2 diabetes. So it seems that some of the adverse health behaviours associated with depressive symptoms were an important component of that relationship (between depression and diabetes)."

Golden added that depression also pushes up the levels of stress hormones such as cortisol. Diabetes is a disease marked by high levels of sugar in the blood. In type-2 diabetes, the body becomes resistant to the effects of the hormone insulin or the body produces some, but not enough, insulin to keep a normal blood sugar level.