Objectives: Augmentation index (AIx) is associated with increased arterial stiffness. However, several reports have shown that AIx is not significantly raised in patients with type 2 diabetes (T2DM) despite having increased arterial stiffness. This suggests different mechanisms contributing to AIx in T2DM, although the exact cause is unknown. The aim of this study was to examine haemodynamic determinates of AIx in healthy people compared with T2DM.

Methods: Resting haemodynamics were recorded in 53 T2DM patients (aged 61±8 years, 51% male) and 53 matched controls (aged 58±6, 51% male). Tonometry was used to record AIx, central blood pressure (BP) and aortic stiffness (aPWV). Cardiac output (CO) and systemic vascular resistance (SVR) were measured using impedance cardiography.

Results: There was no significant difference between groups in AIx (24±11 vs 27±9%, p=0.107). T2DM patients had significantly higher aPWV (7.6±1.6 vs 6.8±1.9 m/s), heart rate (64±9 vs 57±7.0 bpm), CO (5.54±1.15 vs 4.49±0.71 L/min), and central SBP (114±12 vs 107±12 mmHg), but lower SVR (1326±249 vs 1559±281d.s.cm⁻⁵)(p<0.05 all). The strongest correlates of AIx in T2DM patients were heart rate (r=−0.632), CO (r=−0.604) and SVR (r=0.542)(p<0.001 all). However, these were not related to AIx in controls, where the strongest correlate was central systolic BP (r=0.587; p<0.001). aPWV was not related to AIx in either group (p>0.05 both).

Conclusions: Haemodynamic determinants of AIx in T2DM patients are significantly different to healthy people where BP is a dominant factor. In patients with T2DM, however, a high output, low resistance haemodynamic environment is associated with AIx.