Objective: Diabetes is a leading cause of morbidity and mortality. The purpose of this study is to assess the associations between diabetes complications and mortality in the Early Treatment Diabetic Retinopathy Study (ETDRS).
Research design and methods: We examined demographic, clinical, and laboratory characteristics of the 3,711 subjects enrolled in the ETDRS, a randomized controlled clinical trial designed to evaluate the role of laser photocoagulation and aspirin therapy for diabetic retinopathy. The outcome assessed was all-cause mortality. Multivariable Cox proportional hazards regression was used to assess associations between diabetes complications and mortality for type 1 and type 2 diabetes separately.
Results: The 5-year estimates of all-cause mortality were 5.5 and 18.9% for patients with type 1 and type 2 diabetes, respectively. In patients with type 1 diabetes, amputation (hazard ratio [HR] 5.08 [95% CI 2.06-12.54]) and poor visual acuity (1.74 [1.10-2.75]) remained significantly associated with mortality, after adjusting for other diabetes complications and baseline characteristics. In patients with type 2 diabetes, macrovascular disease and worsening levels of nephropathy, neuropathy, retinopathy, and visual acuity are associated with progressively increasing risks of mortality, after controlling for other baseline risk factors.
Conclusions: Amputation is the strongest predictor for mortality in patients with type 1 diabetes. All complications independently predict mortality in patients with type 2 diabetes. There is an increased risk for mortality as the degree of each complication worsens. Additional studies are needed to investigate the effectiveness of tertiary prevention to decrease mortality in these patients.