Does literacy mediate the relationship between education and health outcomes? A study of a low-income population with diabetes.

OBJECTIVES We sought to determine whether literacy mediates the relationship between education and glycemic control among diabetes patients. METHODS We measured educational attainment, literacy using the Short Test of Functional Health Literacy in Adults (s-TOFHLA), and glycemic control (HbA1c) in 395 diabetes patients at a U.S. public hospital. We performed path analysis to compare two competing models to explain glycemic control. The direct effects model estimated how education was related to HbA1c; the mediational model estimated the strength of the direct relationship when the additional pathway from education to literacy to HbA1c was added. RESULTS Both the model with a direct effect of education on HbA1c and the model with literacy as a mediator were supported by good fit to observed data. The mediational model, however, was a significant improvement, with the additional path from literacy to HbA1c reducing the discrepancy from observed data (p < 0.01). After including this path, the direct relationship between education and HbA1c fell to a non-significant threshold. CONCLUSIONS In a low-income population with diabetes, literacy mediated the relationship between education and glycemic control. This finding has important implications for both education and health policy.