Even Subclinical Depression Seems Linked to Poorer Diabetes Self-Care

September 12, 2007 — Among outpatients with type 2 diabetes mellitus, even low levels of depressive symptoms are associated with nonadherence to important aspects of diabetes self-care, according to a study published in the September issue of Diabetes Care.
The more symptoms of depression that a diabetic patient had, the more likely they were to be nonadherent to various aspects of diabetes self-care, regardless of whether they met criteria for a likely clinical diagnosis of major depressive disorder, lead study author Jeffrey S. Gonzalez, PhD, from Harvard Medical School in Boston, Massachusetts, told Medscape. He noted the clinical implications of their findings: "Since we know that depression in diabetes is associated with higher risks of complications, poorer diabetes control, and even increased mortality, it's really crucial to evaluate patients and offer appropriate treatment when necessary."
Dr. Gonzalez explained that previous studies have shown that, among individuals with type 2 diabetes, depression is associated with poorer self-care and medical adherence. He added that most studies, however, focused on depression as a clinical variable that is either present or absent. In the current study, they aimed to look at the relationship between self-care and medication adherence among patients with type 2 diabetes across the full range of depression severity.
The researchers surveyed 879 patients with type 2 diabetes who were being seen in 2 primary care clinics.
The 10-item Harvard Department of Psychiatry/National Depression Screening Day Scale (HANDS) survey was used to assess the patients' symptoms of depression during the previous 2 weeks. A HANDS score of 9 or greater — from a possible score of 0 to 30 — was defined as probable major depression.
The Summary of Diabetes Self-Care Activities Questionnaire was used to assess whether, during the previous week, the patients adhered to recommended diabetes self-care measures for general diet, spacing of carbohydrates, exercise, glucose monitoring, fruit and vegetable intake, high-fat food intake, and foot care. An additional question was added to determine adherence to medication.
Depression Common, Linked With Poorer Self-Care Behaviors
Depression was quite prevalent in this primary care sample. Nearly one fifth (19.3%) of the patients met the criteria for major depressive disorder, and another two thirds (66.5%) reported at least some depressive symptoms. Of the patients classed as having probable major depression, only 59.4% had it listed in their medical records.
After controlling for relevant covariates, compared with the other patients, those with probable major depression (HANDS score, ≥ 9) were significantly more likely to report poorer adherence to general dietary recommendations, poorer spacing of carbohydrates throughout the day, not eating 5 or more fruits and vegetables daily, less frequent blood glucose monitoring, and less adherence to exercise recommendations; they were also 2.31 times more likely to have missed 1 or more prescribed medications during the past week (95% confidence interval [CI], 1.50 - 3.56; P < .001). Foot care and high-fat food consumption were not significantly different in the 2 patient groups.
The depressive symptom severity score was a better predictor than major depression for nonadherence to diet, exercise, and medication regimens, but it did not predict glucose monitoring. Only major depression, and not subclinical depression, was associated with decreased self-monitoring of blood glucose.
Among the patients not meeting the criteria of major depression (n = 709), increasing HANDS scores were incrementally associated with poorer self-care behaviors.
"This pattern of results suggests that even minimal symptoms of depression could be problematic for patients with type 2 diabetes," said Dr. Gonzalez.
The presence of symptoms of depression in type 2 diabetes mellitus may hinder a patient's ability to adhere to a self-care routine, he added. "Depressive symptoms such as diminished interest, fatigue, concentration difficulties, and feelings of hopelessness could each interfere with the hard work that's involved in diabetes self-care," he observed. "These patients might benefit from extra support or from a referral to psychological services, especially when their symptoms are impacting functioning or causing distress."
This study was supported by a grant from Pfizer with additional support from Aventis and the Massachusetts General Hospital Clinical Research Program. Dr. Gonzalez was also supported by a grant from the National Institute of Mental Health. Additional financial relationships for the other investigators are listed in the original article.
Diabetes Care. 2007;30:2222-2227.