Diabetes often coexists with mental health problems such as depression. Research suggests that this link goes in two directions—that is, adults with Type 2 diabetes are twice as likely as non-diabetic adults to develop depression, and depressed adults also have an increased risk of developing Type 2 diabetes. Diabetes, in turn, accounts for about 50% of new cases of end-stage kidney disease, where kidney function declines to the point that a patient requires renal replacement therapy—namely, kidney transplant or dialysis. Depression is often accompanied by negative health behaviours (such as failing to follow treatment plans or advice to modify one’s diet, exercise, and smoking habits) and thus, poorer health outcomes.
Given these links, our study sought to determine whether diabetic patients with depression were at greater risk of chronic kidney disease (CKD), coronary heart disease events, stroke, and overall mortality than those who were not depressed. The results of our study were published in the November 2016 issue of Diabetes Care.
Patients with both diabetes and depression did have a higher risk of developing CKD. They were also at significantly higher risk of strokes, coronary events (including heart attack, bypass surgery, and angioplasty), and mortality from all causes.
Our research subjects were selected from a group of over 3 million U.S. military veterans whose kidney function was in the normal range—that is, whose estimated glomerular filtration rate (eGFR) was greater than 60 ml/min/1.73 m2. From this largely middle-aged and elderly group with a variety of co-existing health problems and a heightened risk of cardiovascular disease, we studied 340,806 veterans with both diabetes and depression, and 592,405 who had diabetes without depression. The first available assessment of these patients took place between October 2004 and September 2006, at which point their initial kidney function was normal. The follow-up period was between October 1, 2006 and either the final healthcare visit or the end date of our study (July 26, 2013). All relevant kidney, coronary, or stroke events or deaths that were recorded during this period were abstracted into our database.
We found that patients who had both diabetes and depression did have a higher risk of developing CKD during the follow-up period, compared to non-depressed patients, even after correcting for social and demographic factors. We found these patients were also at significantly higher risk of strokes, coronary events (including heart attack, bypass surgery, and angioplasty), and mortality from all causes. This was particularly notable given that the patients with depression were somewhat younger overall and started out with higher levels of kidney function (as defined by higher eGFR levels), although more co-existing disorders too, when the study began.
Next research steps
We propose that future studies should focus on determining whether treating depression effectively in patients with diabetes would lower their rates of chronic kidney disease, cardiovascular events and death.
Link to paper: https://www.ncbi.nlm.nih.gov/pubmed/27311494