Gonzalez JS et al. (2008) Depression and diabetes treatment nonadherence: a meta-analysis. Diabetes Care 31: 2398–2403

A new study suggests that depression might be associated with nonadherence to treatment in patients with diabetes mellitus.

Gonzalez and colleagues performed a meta-analysis of 47 studies published since 1950 that aimed to evaluate the relationship between depression and self-care behaviors in 17,319 patients with diabetes mellitus. Variables assessed included type of self-care regimen, type of diabetes mellitus, life stage, research design, level of treatment adherence, use of validated versus nonvalidated measures for depression, and use of objective versus nonobjective measures for self-care. Treatment nonadherence was broadly defined as poor adherence to medication, diet, physical exercise, glucose testing, foot examination, or scheduled medical appointments.

The authors found that depression significantly correlated with poor self-care (P <0.0001). The weighted effect size of this association was in the moderate range (r = 0.21, 95% CI 0.17–0.25). The observed association between depression and self-care varied by care regimen: missed medical appointments had the greatest effect (r = 0.31, 95% CI 0.29–0.34) and foot examination had the smallest (r = 0.07, 95% CI −0.08–0.21). Potential moderators of the association between depression and self-care included diet, medication adherence and glucose testing; however, the relationship was unaffected by type of diabetes mellitus.

The presence of concomitant depression can worsen the outcomes of patients with diabetes mellitus. Gonzalez et al. conclude that poor self-care behaviors might represent an important link between these two conditions.