I have diabetes -- and I'm depressed

New research from the US shows possible link between these two conditions -- could it be the fat?

By Williams D Donaldson

Having type II diabetes is bound to be somewhat depressing, considering the impact the disease has on overall health. But according to new American research, it cuts both ways -- suffering from depression appears to increase the risk of developing type II diabetes. In a study of more than 11,000 individuals, subjects in the highest quartile of depressive symptoms had a 63% increased risk of developing type II diabetes compared to those in the lowest quartile.

Researchers from Johns Hopkins University, Emory University and the University of Wisconsin followed a longitudinal, biracial cohort study of 11,615 initially nondiabetic adults for six years, tracking the relationship of depression to the subsequent development of diabetes. The research is published in the February issue of the journal Diabetes Care.

The researchers observed a positive association at baseline between depressive symptoms and body mass index, physical inactivity, systolic blood pressure, fasting insulin, caloric intake and current smoking. They recorded 721 cases of incident type II diabetes over six years of follow-up. This corresponded to an overall incidence rate of 12.4 cases per 1000 person-years.

The association between depression and diabetes was weaker when the researchers controlled for stress-associated lifestyle factors. In this analysis, the top quartile proved 28% more likely to develop diabetes. When the researchers controlled for metabolic factors, the diabetes risk was 38% higher for the top depression quartile compared to the lowest quartile.

One possible cause for the link, the authors speculated, is antidepressants that may be causing weight gain. On the other hand, they suggested, "depressed individuals are less likely to be compliant with dietary and weight loss recommendations and are more likely to be physically inactive and nonadherent with medications."

Another explanation put forward by the researchers is the known relationship between low socioeconomic status and both diabetes and depression. Finally, there is the possibility that neurohormonal changes caused by either depression or antidepressants may have physical effects conducive to the development of diabetes.

The authors wrote: "Our study serves as a springboard for additional prospective studies using an established assessment tool to demonstrate an association between depression and diabetes with inclusion of neurohormonal measurements."

They argued that further research is needed to determine whether sympathetic nervous system activation and the HPA axis, the classical stress-activated neuroendocrine system, play an important role in the pathophysiology of weight gain and insulin resistance.

"Additional studies should determine whether amelioration of depressive symptoms might facilitate behavioural changes aimed at primary prevention of diabetes," they concluded.