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Augmentation of central arterial pressure in Type 2 diabetes
B A Brooks1, L M Molyneaux, D K Yue
1The Diabetes Centre, Royal Prince Alfred Hospital and Department of Medicine, The University of Sydney, Sydney, Australia. belinda@diab.rpa.cs.nsw.gov.au
Aims:
Aortic systolic blood pressure has been shown to be augmented in Type 1 diabetes, indicative of more rapid pulse wave reflection due to increased arterial stiffness. This abnormality is more pronounced in diabetic males. The aim of this study was to examine the effects of diabetes on augmentation of aortic systolic pressure in subjects with Type 2 diabetes.
Methods:
Radial artery pressure waveforms were obtained non-invasively by applanation tonometry. A central aortic waveform can be derived using a transfer function obtained from previous studies during cardiac catheterization. A total of 88 subjects with Type 2 diabetes (51 men and 37 women, aged 55.8 years (interquartile range (IR) 49.7-64.1), duration of diabetes 7.5 years (IR 2.4-12.4), HbA1c 7.6% (IR 6.6-8.7)) and 85 controls subjects (40 men and 45 women, aged 55.3 years (IR 44.2-66.4)) were studied. The central aortic waveform allowed determination of the: (i) aortic augmentation index and (ii) subendocardial viability ratio.
Results:
Similar to Type 1 diabetic subjects, patients with Type 2 diabetes had a significantly higher aortic augmentation index (136.1 +/- 18.0% vs. 128.3 +/- 19.2%, t = 2.8, P = 0.006) and lower subendocardial viability ratio (137.4 +/- 25.0% vs. 155.1 +/- 25.9%; t = 4.6, P = 0.0001) compared with controls. Multivariate analysis identified diabetes as an important determinant of aortic augmentation index (t = 4.0, P = 0.0001). The higher aortic augmentation index was due mainly to the male cohort (t = 2.6; P = 0.01) and was not apparent for females with diabetes (P = 0.2).
Conclusions:
Type 2 diabetes is characterized by higher augmentation of aortic systolic pressure and unfavourable ratio of myocardial perfusion to cardiac workload. These results are consistent with increased arterial stiffness. The age-related progression of arterial stiffness is similar in Type 1 and Type 2 diabetes. Anti-hypertensive agents that reduce wave reflection and augmentation may help to prevent systolic hypertension and cardiac hypertrophy in diabetes.