Hyperglycemia and incidence of frailty and lower extremity mobility limitations in older women

Objectives To determine the degree to which hyperglycemia predicts the development of frailty and lower extremity mobility limitations. Design Secondary data analysis of longitudinal data collected in a prospective cohort study. Setting Baltimore, Maryland. Participants Three hundred twenty-nine women from the Women's Health and Aging Study II aged 70 to 79 at baseline who had all variables needed for analysis. Measurements Glycosylated hemoglobin (HbA1c) at baseline, categorized as less than 5.5%, 5.5% to 5.9%, 6.0% to 6.4%, 6.5% to 7.9%, and 8.0% and greater, was the independent variable. The incidence of frailty and lower extremity mobility limitations (based on self-reported walking difficulty, walking speed, and Short Performance Physical Battery score) was determined (follow-up ≈ 9 years). Frailty was assessed using the Cardiovascular Health Study criteria. Covariates included demographic characteristics, body mass index, interleukin-6 level, and clinical history of comorbidities. Statistical analyses included Kaplan-Meier survival curves and Cox regression models adjusted for important covariates. Results In time-to-event analyses, HbA1c category was associated with incidence of walking difficulty (P =.049) and low physical performance (P =.001); association with incidence of frailty and low walking speed had a trend toward significance (both P =.10). In regression models adjusted for demographic characteristics, HbA1c of 8.0% or greater (vs < 5.5%) was associated with an approximately three-times greater risk of incident frailty and three to five times greater risk of lower extremity mobility limitations (all P <.05). In fully adjusted models, HbA1c of 8.0% or greater (vs < 5.5%) was associated with incident frailty (hazard ratio (HR) = 3.33, 95% confidence interval (CI) = 1.24-8.93), walking difficulty (HR = 3.47, 95% CI = 1.26-9.55), low walking speed (HR = 2.82, 95% CI = 1.19-6.71), and low physical performance (HR = 3.60, 95% CI = 1.52-8.53). Conclusion Hyperglycemia is associated with the development of frailty and lower extremity mobility limitations in older women. Future studies should identify mediators of these relationships.