Hemoglobin A1c Predicts Healing Rate in Diabetic Wounds

Lower-extremity wounds are a major complication of diabetes. Hemoglobin A1c (HbA1c) reflects glycemia over 2-3 months and is the standard measure used to monitor glycemia in diabetic patients, but results from studies have not shown a consistent association of HbA1c with wound healing. We hypothesized that elevated HbA1c would be most associated with poor wound healing. To test this hypothesis, we conducted a retrospective cohort study of 183 diabetic individuals treated at the Johns Hopkins Wound Center. Our primary outcome was wound-area healing rate (cm(2) per day). Calibrated tracings of digital images were used to measure wound area. We estimated coefficients for healing rate using a multiple linear regression model controlling for clustering of wounds within individuals and other common clinic variables. The study population was 45% female and 41% African American, with a mean age of 61 years. Mean HbA1c was 8.0%, and there were 2.3 wounds per individual (310 wounds total). Of all measures assessed, only HbA1c was significantly associated with wound-area healing rate. In particular, for each 1.0% point increase in HbA1c, the daily wound-area healing rate decreased by 0.028 cm(2) per day (95% confidence interval: 0.003, 0.0054, P = 0.027). Our results suggest that glycemia, as assessed by HbA1c, may be an important biomarker in predicting wound-healing rate in diabetic patients.