To the Editor: The study by Dr Golden and colleagues1 showed that baseline depressive symptoms were associated with subsequent incidence of type 2 diabetes. Additionally, treated type 2 diabetes was associated with subsequent depressive symptoms.
However, evaluating the association between diabetes and incident depressive symptoms should take into account that affective diseases such as recurrent major depressive disorder and bipolar disorder can fully remit between episodes. Thus, the absence of depressive symptoms during a 1-week time frame could represent a state of a remitted bipolar or recurrent depressive disorder. To investigate diabetes as a possible risk factor for the development of depressive disorder, the authors should have assessed whether there were manic or major depressive episodes before study enrollment.
Schulte-Herbrüggen O, Bahri S, Röpke S. Depressive Symptoms and Diabetes. JAMA. 2008;300(18):2115-2116. doi:10.1001/jama.2008.564