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Australian research sheds light on relationship between depression and duration of diabetes

The risk of depression falls during the second decade following a type 1 diabetes or type 2 diabetes diagnosis, but then rapidly increases, according to Australian researchers.
In this new study, researchers from the School of Psychiatry % Clinical Neurosciences, University of Western Australia, examined if diabetes and the duration of diabetes causes depression in later life, either directly or indirectly.
They conducted a cross-sectional, community study of 5462 men aged between 70 and 89 years. The presence and duration of diabetes was established by self-reported history, use of insulin or drugs that can cause hypoglycemia or fasting glucose levels above 7 mmol/l. No differentiation was made between type 1 and type 2 diabetes.
Current depression was identified using the Geriatric Depression Scale (GDS-15), while men with “ever depression” were either currently depressed or had reported treatment for past depression.
Diabetes was associated with an increased risk of both ever depression and current depression, but this link was “J-shaped”. The risk of current depression was higher in the first and third decades of diabetes duration, but lower in the second. These findings were in comparison to older men who did not have diabetes.
However, the strength of the relationship was reduced when factors such as age, education, smoking history and frailty were taken into account.
The researchers suggested that this J-shaped relationship could indicate that patients initially experience mental health benefits from medication and acceptance of their diabetes.
Dr. Dimitry S Davydown, MD, MPH, University of Washington School of Medicine, who wasn’t involved in the study, commented: “There’s lots of research that’s previously found, essentially, that diabetes and depression share a bidirectional relationship, meaning that depression earlier in life raises your risk of a lot of things: not exercising, smoking, and obesity and [factors]…that lead to developing diabetes. Conversely, diabetes and diabetes-related complications can raise your risk of developing depression.”

Davydow added that a limitation of the study was that depression and diabetes were assessed at a single point in time. This increased the risk of recall bias when participants were asked about prior depression.
The researchers concluded: “The introduction of strategies that are effective at decreasing diabetes-related complications may also contribute to decrease the risk of depression among older men.”
The study was published online in Maturitas.

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