Abstract
BACKGROUND: Reduced red blood cell deformability (RBCD) is associated with diabetic vascular complications, but early pathophysiological RBC changes and predictive demographic and clinical factors in populations with diabetes are unclear. An understanding of early diabetes-specific RBC changes associated with impaired RBCD is essential in investigating mechanisms that predispose to diabetic vascular complications. METHODS: We conducted an outpatient cross-sectional study of participants in a well-controlled diabetes cohort (N81) and nondiabetic controls (N78) at the National Institutes of Health. First, between-group differences in RBCD measures were assessed with shear stress-gradient ektacytometry. Differences in structural RBC parameters were assessed using osmotic gradient ektacytometry and NaCl osmotic fragility. Functional RBC changes were assessed using hemoglobin-oxygen dissociation: p50. RESULTS: All shear-stress gradient RBCD measures were significantly altered in the diabetes cohort vs. nondiabetic controls, even after adjustment for confounding covariates (p < 0.001). Adjusted for diabetes-status and demographic factors, significant predictors of reduced RBCD included older age, Black race, male gender, hyperglycemia, and vascular complications (all p < 0.05). Reduced RBCD was also associated with aberrant osmotic-gradient parameters, with a left-shift on osmotic gradient profile indicative of dehydrated RBCs in diabetes. A structure-function relationship was observed with reduced RBCD associated with reduced osmotic fragility (P < 0.001) and increased hemoglobin-oxygen dissociation (P < 0.01). CONCLUSIONS: Findings suggest impaired RBCD incurs similar demographic and clinical risk factors as diabetic vascular disease, with early pathophysiological RBC changes indicative of disordered RBC hydration in diabetes. Findings provide strong evidence for disordered oxygen release as a functional consequence of reduced RBCD. CLINICAL TRIAL NUMBER: NCT00071526.