“This study came from a simple idea,” said lead author Jay A. Brieler, MD, Assistant Professor of Family and Community Medicine at Saint Louis University School of Medicine. “We already know from previous studies that depression and diabetes are closely linked in a bi-directional manner. Those with depression are more likely to get diabetes, and those with diabetes are more likely to get depressed. The next obvious question, for us, was to find out whether treating one condition would help with the other. Could the connection have treatment implications?”
“The result of our study was that treating depression was associated with better control of blood sugar. So at some level the answer to the question is yes,” Dr. Brieler told EndocrineWeb. “Our study adds to the evidence that it is very important to treat depression among diabetic patients.”
“This study is an important reminder of the link between depression and diabetes, and it adds to our evidence base about the importance of treating depression in patients who have diabetes,” commented Jennifer Frost, MD, Medical Director for the Health of the Public and Science Division of the American Academy of Family Physicians (AAFP).
Retrospective Study Design
Dr. Brieler and colleagues retrospectively studied electronic medical record registry data from 1,399 people (aged ≥18 years) with type 2 diabetes who attended a primary care visit at least once between 2008 and 2013. Of this group, 1,134 were not diagnosed with depression; 225 were diagnosed with depression and taking antidepressants, and 40 were diagnosed with depression and not treated with antidepressants.
Patients With Treated Depression Had the Lowest A1c
The average A1c was lowest among patients with treated depression and was highest among those with untreated depression, with non-depressed patients in the middle (7.4%, 8.1%, and 7.7% mmol/mol, respectively). Similarly, the percentage of patients who achieved good glycemic control (ie, hemoglobin A1c <7.0%) was highest in the treated depressed group and lowest for the untreated depressed group, with the non-depressed group in the middle (50.9%, 34.6%, and 42.7%).
Patients with treated depression were significantly more likely to achieve glycemic control compared to those with untreated depression (odds ratio [OR] = 1.95; P<0.05) in a multivariate analysis that adjusted for co-morbidities, health behaviors, and socio-demographics. Other factors that were significantly and positively associated with glucose control were anxiety disorder (OR = 2.12; P<0.01) and age (OR = 1.01; P<0.05), while prescription of insulin (OR = 0.17; P<0.001) or other diabetic medication (OR = 0.37; P<0.001) was inversely associated with control.
“Previous work in this area is very limited,” Dr. Brieler said. “Our study adds significantly to the total number of patients in the literature. In addition, our study was conducted on data from primary care patients in an actual practice setting. This makes it more likely that the results apply to other primary care practices.”
Possible Mechanisms Behind Antidepressants’ Effects on Blood Glucose Control
While it unclear what the exact mechanisms behind the beneficial effects of antidepressants on blood glucose control are, “it is likely that improvements in depression lead to improvements in behavioral change—better diet, more frequent exercise, regularly taking medication and checking blood sugar. There might also be a direct physiologic effect related to stress hormones. This will be an important area for future research,” Dr. Brieler said.
“This is just one study among many that emphasizes the effects of depression on physical health,” Dr. Brieler said. “Depression is not only a disease of emotions and behavior. Depression is a risk factor for vascular disease, diabetes, and worse outcomes after heart surgery. Proper treatment of depression is important for many aspects of a patient's health.”
“Depression is very common, but unfortunately, many people with depression go undiagnosed, or don’t get the treatment they need,” Dr. Frost commented. “To combat this issue, the AAFP advises primary care physicians to screen for depression in all adults.”
January 27, 2016
Brieler JA, Lustman PJ, Scherrer JF, Salas J, Schneider FD. Antidepressant medication use and glycaemic control in co-morbid type 2 diabetes and depression. Fam Pract. 2016 Jan 7. pii: cmv100. [Epub ahead of print]