Aims To examine prospectively the association of depression symptoms with subsequent self-care and medication adherence in patients with Type 2 diabetes mellitus.
Methods Two hundred and eight primary care patients with Type 2 diabetes completed the Harvard Department of Psychiatry/National Depression Screening Day Scale (HANDS) and the Summary of Diabetes Self-Care Activities (SDSCA) at baseline and at follow-up, an average of 9 months later. They also self-reported medication adherence at baseline and at a follow-up.
Results Baseline HANDS scores ranged from 0 to 27, with a mean score of 5.15 ± 4.99. In separate linear regression models that adjusted for baseline self-care, patients with higher levels of depressive symptoms at baseline reported significantly lower adherence to general diet recommendations and specific recommendations for consumption of fruits and vegetables and spacing of carbohydrates; less exercise; and poorer foot care at follow-up (β ranging from −0.12 to −0.23; P < 0.05). Similarly, each one-point increase in baseline HANDS score was associated with a 1.08-fold increase in the odds of non-adherence to prescribed medication at follow-up (95% confidence interval 1.001, 1.158, P = 0.047). Increases in depression scores over time also predicted poorer adherence to aspects of diet and exercise.
Conclusions Depressive symptoms predict subsequent non-adherence to important aspects of self-care in patients with Type 2 diabetes, even after controlling for baseline self-care. Although the relationship between symptoms of depression and poorer diabetes self-care is consistent, it is not large, and interventions may need to address depression and self-care skills simultaneously in order to maximize effects on diabetes outcomes.