Interarm blood pressure difference in people with diabetes: measurement and vascular and mortality implications: a cohort study.

Abstract

Differences in blood pressure between arms are associated with vascular disease and increased mortality; this has not been reported in diabetes. We explored these associations, and assessed reference standard and pragmatic measurement techniques, in people with diabetes and in nondiabetic controls. A prospective cohort study in Devon, England, recruited 727 people with type 1 or type 2 diabetes and 285 nondiabetic controls. Simultaneous repeated measurements of bilateral blood pressure were made at recruitment. Data were used to inform a pragmatic measurement strategy. Interarm differences were examined for cross-sectional associations with target organ disease and prospective mortality associations (median follow-up 52 months). We found 8.6% of participants with diabetes and 2.9% of controls had systolic interarm differences ≥10 mmHg. Single pairs of blood pressure measurements had high negative predictive values (97-99%) for excluding interarm differences. Systolic interarm differences ≥10 mmHg in diabetes were associated with peripheral arterial disease (odds ratio [OR] 3.4 [95% CI 1.2-9.3]). Differences ≥15 mmHg were associated with diabetic retinopathy (OR 5.7 [1.5-21.6]) and chronic kidney disease (OR 7.0 [1.7-29.8]). Systolic interarm differences were associated prospectively with increased cardiovascular mortality: hazard ratios 3.5 (1.0-13.0) for ≥10 mmHg and 9.0 (2.0-41.0) for ≥15 mmHg. Blood pressure should be measured in both arms during initial assessment in diabetes. Systolic interarm differences can be excluded with a single pair of measurements. In the population with diabetes, systolic differences may be associated with an increased risk of morbidity and mortality.