Changes in pulse pressure, heart rate and the pulse pressure × heart rate product during squatting in Type 1 diabetes according to age

Abstract

We assessed changes in pulse pressure and heart rate during a squatting test, as indirect markers of arterial stiffness and cardiovascular autonomic neuropathy, respectively, according to age and sex in patients with Type 1 diabetes mellitus. We evaluated 160 diabetic patients, divided into four groups of 20 men and 20 women according to age (G1, 20-30 years old; G2, 31-40 years old; G3, 41-50 years old; and G4, 51-60 years old), and 160 non-diabetic matched control subjects. Each subject underwent a 3 min posture test (standing-squatting-standing) with continuous measurement of arterial blood pressure and heart rate by a Finapres device. Overall values throughout the test, baseline levels in initial standing position and squatting-induced changes in pulse pressure, heart rate and the pulse pressure x heart rate product were compared between diabetic patients and healthy control subjects. In the standing position, a greater increase in pulse pressure and lower reduction in heart rate with age led to a significantly higher pulse pressure x heart rate product in diabetic patients compared with control subjects. In the squatting position, a more marked pulse pressure increase in the absence of appropriate reduction in heart rate resulted in a greater rise in the pulse pressure x heart rate product in diabetic patients than in healthy subjects. No major differences were noted between the sexes, with the exception of a stronger relationship between pulse pressure and age in the female population with diabetes. Squatting-derived indices of cardiovascular autonomic neuropathy were also noted with increasing age in diabetic patients. The marked increase in the pulse pressure x heart rate product ('pulsatile stress') according to age, combined with cardiovascular autonomic neuropathy, may contribute to the higher cardiovascular risk of patients with Type 1 diabetes.