Depression and Advanced Complications of Diabetes: A prospective cohort study

OBJECTIVE: To prospectively examine the association of depression with risks for advanced macrovascular and microvascular complications among patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: A longitudinal cohort of 4,623 primary care patients with type 2 diabetes was enrolled in 2000-2002 and followed through 2005-2007. Advanced microvascular complications included blindness, end-stage renal disease, amputations, and renal failure deaths. Advanced macrovascular complications included myocardial infarction, stroke, cardiovascular procedures, and deaths. Medical record review, ICD-9 diagnostic and procedural codes, and death certificate data were used to ascertain outcomes in the 5-year follow-up. Proportional hazard models analyzed the association between baseline depression and risks of adverse outcomes. RESULTS: After adjustment for prior complications and demographic, clinical, and diabetes self-care variables, major depression was associated with significantly higher risks of adverse microvascular outcomes (hazard ratio 1.36 [95% CI 1.05-1.75]) and adverse macrovascular outcomes (1.24 [1.0-1.54]). CONCLUSIONS: Among people with type 2 diabetes, major depression is associated with an increased risk of clinically significant microvascular and macrovascular complications over the ensuing 5 years, even after adjusting for diabetes severity and self-care activities. Clinical and public health significance of these findings rises as the incidence of type 2 diabetes soars. Further research is needed to clarify the underlying mechanisms for this association and to test interventions to reduce the risk of diabetes complications among patients with comorbid depression.