Lower hemoglobin concentration is associated with retinal ischemia and the severity of diabetic retinopathy in type 2 diabetes

Abstract

Aims. To assess the association of blood oxygen-transport capacity variables with the prevalence of diabetic retinopathy (DR), retinal ischemia, and macular oedema in patients with type 2 diabetes mellitus (T2DM). Methods. Cross-sectional, case-control study (N = 312) with T2DM: 153 individuals with DR and 159 individuals with no DR. Participants were classified according to the severity of DR and the presence of retinal ischemia or macular oedema. Hematological variables were collected by standardized methods.Three logisticmodelswere adjusted to ascertain the association between hematologic variableswith the severity ofDR and the presence of retinal ischemia or macular oedema. Results. Individuals with severe DR showed significantly lower hemoglobin, hematocrit, and erythrocyte levels compared with those with mild disease and in individuals with retinal ischemia and macular oedema compared with those without these disorders.Hemoglobin was the only factor that showed a significant inverse association with the severity of DR [beta-coefficient = −0.52, P value = 0.003] and retinal ischemia [beta-coefficient = −0.49, P value = 0.001]. Lower erythrocyte level showed a marginally significant association with macular oedema [beta-coefficient = −0.86, P value = 0.055]. Conclusions. In patients withDR, lowblood oxygen-transport capacity was associatedwithmore severeDR and the presence of retinal ischemia. Low hemoglobin levels may have a key role in the development and progression of DR.

This project was funded by Grant nos. PS09/01035 and PI12/00183, both included in Plan Nacional de I+D+I and cofinanced by Instituto de Salud Carlos III-Subdireccion General de Evaluaci´on and Fondo Europeo de Desarrollo Regional (FEDER).