Peripheral arterial compliance is lower in Afro-Caribbeans compared to white Caucasians with type 2 diabetes after adjustment for blood pressure

Abstract

Arterial compliance declines with age. However this decline occurs more rapidly in both the hypertensive and diabetic states. Afro-Caribbeans have a higher prevalence of hypertension and other complications of diabetes than the indigenous white Caucasian population. We hypothesise that accelerated decline in arterial compliance may account for this racial difference. Forty-one volunteers, age 62.5 ± 6.8 years (mean ± s.d., range 48–75), were selected from diabetic clinics. Twenty-one were Caucasian and 20 were Afro-Caribbean. Pulse wave velocity (PWV) was measured using non-invasive techniques: the ‘Complior’ system was used to record PWV in the carotid-to-radial (C-R) and carotid-to-femoral (C-F) regions. Central arterial compliance (CAC) was measured by simultaneous aortic flow velocimetry and carotid artery applanation tonometry. The duration of diabetes was taken as the time from clinical diagnosis. Baseline characteristics in the two racial groups were comparable for age, BMI, cholesterol, HbA1c, blood pressure and duration of diabetes. Comparing the PWV in the C-F region showed that the mean PWV was 13.84 ± 0.28 m/sec in the Caucasians and 13.97 ± 0.34 m/sec in the Afro-Caribbeans (P = 0.86) whereas in the C-R region the mean PWV was 11.13 ± 0.28 m/sec in Caucasians and 12.10 ± 0.34 m/sec in the Afro-Caribbeans (P = 0.03). In agreement with the C-F findings there was no statistical difference in CAC between the two races. Adjustment of PWV in the carotid-radial (C-R) region for systolic and diastolic blood pressure, confirmed that the racial differences were independent of blood pressure (difference 0.91 m/sec, P = 0.046 after adjustment for diastolic pressure and 0.89 m/sec, P = 0.056 after adjustment for both systolic and diastolic blood pressure). Accelerated decline in peripheral arterial compliance may account for the increased stroke rate with diabetes in Afro-Caribbeans.