Sex differences in step count-blood pressure association: A preliminary study in type 2 diabetes

Abstract

Background: Walking and cardiovascular mortality are inversely associated in type 2 diabetes, but few studies have objectively measured associations of walking with individual cardiovascular risk factors. Such information would be useful for "dosing" daily steps in clinical practice. This study aimed to quantify decrements in blood pressure and glycated hemoglobin (A1C) per 1,000 daily step increments. Methodology/Principal Findings: Two hundred and one subjects with type 2 diabetes underwent assessments of step counts (pedometer-measured), blood pressure, A1C and anthropometric parameters. Due to missing data, the final analysis was conducted on 83 women and 102 men, with a mean age of 60 years. Associations of daily steps with blood pressure and A1C were evaluated using sex-specific multivariate linear regression models (adjusted for age, ethnicity, and BMI). Potential sex differences were confirmed in a combined model (women and men) with interaction terms. Mean values for daily steps, blood pressure, A1C and BMI were 5,357 steps/day; 137/80 mm Hg; 7.7% and 30.4 kg/m2 respectively. A 1,000 daily step increment among women was associated with a 22.6 (95% CI: 24.1 to 21.1) mm Hg change in systolic and a 21.4 (95% CI: 22.2 to 20.6) mm Hg change in diastolic blood pressure. Among men, corresponding changes were 20.7 (95% CI: 22.1 to 0.7) and 20.6 (95% CI: 21.4 to 0.3) mm Hg, respectively. Sex differences were confirmed in combined models. Step counts and A1C did not demonstrate clinically important associations. Conclusions/Significance: A 1,000 steps/day increment is associated with important blood pressure decrements among women with type 2 diabetes but the data were inconclusive among men. Targeted "dose increments" of 1,000 steps/day in women may lead to measurable blood pressure reductions. This information may be of potential use in the titration or "dosing" of daily steps. No associations were found between step count increments and A1C. © 2010 Manjoo et al.