Effects of gender and depression on oral medication adherence in persons with type 2 diabetes mellitus

Background: In a range of chronic conditions including diabetes, it has been observed that depressive symptoms may be associated with nonadherence to medications.Objective: The objective of the study was to determine the main effects, and interactive effect, of depression and gender on patients adherence to oral diabetes medications.Methods: A cross-sectional design was employed, in which persons with type 2 diabetes mellitus completed a questionnaire regarding medication use behaviors, depressive symptoms (measured by the 8-item Patient Health Questionnaire [PHQ-8]), health beliefs, and demographics. A 2 x 2 factorial analysis of variance was used to determine the effects of gender and depression on medication adherence after adjusting for age, education, self efficacy, social support, and number of doses of diabetes medications.Results: Of the 391 respondents who completed the questionnaire, 73 (18.7%) were categorized as having depression (ie, PHQ-8 score >10). Overall, women (n = 196) had a mean (SD) score of 6.10 (6.19) on the PHQ-8, and men (n = 195) had a lower score of 4.62 (5.28) (t = 2.75; P < 0.01). There was a significant main effect of depression, but not gender, on patients' adherence to diabetes medications in that those who were categorized as depressed had significantly worse adherence to diabetes medications (F = 4.82; P = 0.03).Additionally, there was a significant “gender x depression” interaction effect on adherence (F = 5.93; P = 0.01). Men with depression had mean adherence scores that indicated more nonadherence than did men without depression (9.44 [3.45] vs 7.47 [2.50], respectively), but adherence varied little between women with depression and women without depression (7.83 [2.69] vs 7.55 [2.58], respectively).Conclusions: The association between depression and medication adherence appears to be stronger in men than in women. Clinicians should be cognizant of the potential effect of depression on self-care for diabetes, particularly in men with depressive symptoms.