Brachial-to-radial systolic blood pressure amplification in patients with type 2 diabetes mellitus

Brachial-to-radial-systolic blood pressure amplification (Bra-Rad-SBP_Amp) can affect central SBP estimated by radial tonometry. Patients with type 2 diabetes mellitus (T2DM) have vascular irregularities that may alter Bra-Rad-SBP_Amp. By comparing T2DM with non-diabetic controls, we aimed to determine the (1) magnitude of Bra-Rad-SBP_Amp; (2) haemodynamic factors related to Bra-Rad-SBP_Amp; and (3) effect of Bra-Rad-SBP_Amp on estimated central SBP. Twenty T2DM (64 ± 8 years) and 20 non-diabetic controls (60 ± 8 years; 50% male both) underwent simultaneous cuff deflation and two-dimensional ultrasound imaging of the brachial and radial arteries. The first Korotkoff sound (denoting SBP) was identified from the first inflection point of Doppler flow during cuff deflation. Bra-Rad-SBP_Amp was calculated by radial minus brachial SBP. Upper limb and systemic haemodynamics were recorded by tonometry and ultrasound. Radial SBP was higher than brachial SBP for T2DM (136 ± 19 vs 127 ± 17 mm Hg; P < 0.001) and non-diabetic controls (135 ± 12 vs 121 ± 11 mm Hg; P < 0.001), but Bra-Rad-SBP_Amp was significantly lower in T2DM (9 ± 8 vs 14 ± 7 mm Hg; P = 0.042). The product of brachial mean flow velocity × brachial diameter was inversely and independently correlated with Bra-Rad-SBP_Amp in T2DM (β = −0.033 95% confidence interval −0.063 to −0.004, P = 0.030). When radial waveforms were calibrated using radial, compared with brachial SBP, central SBP was significantly higher in both groups (T2DM, 116 ± 13 vs 125 ± 15 mm Hg; and controls, 112 ± 10 vs 124 ± 11 mm Hg; P < 0.001 both) and there was a significant increase in the number of participants classified with ‘central hypertension’ (SBP ≫ 130 mm Hg; P = 0.004). Compared with non-diabetic controls, Bra-Rad-SBP_Amp is significantly lower in T2DM. Regardless of disease status, radial SBP is higher than brachial SBP and this results in underestimation of central SBP using brachial-BP-calibrated radial tonometry.