A research team with the University of Western Australia, Perth, found that the risk of depression doubles after patients receive a diagnosis of diabetes. The risk then decreases during the second decade following diagnosis, but nearly triples after the third decade. 

The cross-sectional study included a community-derived sample of 5,462 men aged 70 to 89. The presence of type 1 or type 2 diabetes was determined by self-report, fasting glucose of 7 mmol/L or higher, or use of insulin or hypoglycemic drugs. 

In all, 17.9 percent of the men either currently had depression (n=353; as identified with the Geriatric Depression Scale) or had a history of depression (n=623).

Diabetes was associated with an increased risk of “ever depression” (current or history; odds ratio [OR], 1.49; 95% CI, 1.25-1.76) and current depression (OR, 1.94; 95% CI, 1.15-2.48). 

The risk for depression was assessed for diabetes durations of less than 10 years, 10 to 19.9 years, 20 to 29.9 years and 30 years or more. The ORs for those duration categories were 1.92 (95% CI, 1.44-2.54), 1.56 (95% CI, 0.89-2.75), 2.49 (95% CI, 1.16-5.32) and 3.13 (95% CI, 1.28-7.63), respectively, as compared with the men who did not have diabetes. After adjustments were made for potential confounding factors, the strength of the associations was attenuated but the J shape held constant. 

The study investigators said their results could suggest that after diabetes has been diagnosed, patients might initially experience mental health benefits from treatment and acceptance of their illness. They said introducing strategies effective in reducing the risk of diabetes-related complications might also help decrease the risk of depression.

Frailty mediated approximately 15 percent of the association between diabetes and depression, the researchers estimated, and was a strong predictor of depression in the cohort studied. 

Dr. Dimitry Davydow with the University of Washington School of Medicine, Seattle, remarked in Medscape that earlier research indicates a bi-directional relationship between diabetes and depression. Having depression earlier in life increases the likelihood of not exercising, smoking, obesity and other risk factors that can contribute to the onset of diabetes. A history of depression can also increase the risk for recurrent depression after diabetes has been diagnosed, which can interfere with patients’ ability to care for themselves, and that inability to provide self-care can lead to a greater risk for diabetes-related complications. Conversely, diabetes and its complications can increase the risk for depression. 

Davydow said further research is needed before definitive conclusions can be drawn regarding the relationship between diabetes, depression and frailty. 

The study findings were published online Jan. 11 in Maturitas.

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