Depression as a Risk Factor for Type 2 Diabetes
Evidence strongly suggests that depression is independent
risk factor for the onset of type 2 diabetes. Knoll, Twisk,
Beekman, Heine, Snoek, & Pouwer examined the causal
association among depression and type 2 diabetes by conducting
a meta-analysis of longitudinal studies [13]. The
pooled relative risk was 1.37; depressed adults have a 37%
increased risk of developing type 2 diabetes. The most recent
meta-analysis of Cosgrove, Sargeant, Griffin confirmed the
causal role of depression or depressive symptoms in developing
type 2 diabetes [14]. The pooled adjusted relative risk
estimate from the 3 highest quality studies was 1.25. Twenty
five percent of cases of diabetes could be attributed to depression
in people with both conditions. Several pathophysiological
mechanisms could explain the increased risk of type
2 diabetes in depressed individuals, including the increased
activity of the HPA axis and sympathetic nervous system,
and dysregulation of the immune system. Furthermore,
physical inactivity, common in depressed individuals, is a
strong risk factor for type 2 diabetes, independently of obesity
[15]. On the other hand, physical activity improves glycemic
control in type 2 diabetes, with greater improvements
for combined aerobic and resistance training compared with
aerobic or resistance training alone [16].