title: Why the radial augmentation index is low in patients with diabetes: The J-HOP study.
abstract: BACKGROUND
  Radial augmentation index (rAI), a marker of aortic wave reflection, is usually lower in patients with diabetes (DM) than in non-DM subjects, even though atherosclerotic change is advanced in DM.
  
  
  OBJECTIVE
  We sought to explore why rAI in DM is lower than in non-DM.
  
  
  METHODS
  We performed radial applanation tonometry in 1787 subjects who had at least one cardiovascular risk factor. The rAI was defined as [late systolic shoulder pressure amplitude (PP2)]/[radial pulse pressure (rPP)]. The late systolic shoulder blood pressure (SBP2) and PP2 of a radial pressure wave were used as estimates of the central SBP and PP (cPP), respectively.
  
  
  RESULTS
  The age (65.8 ± 9.8 vs. 65.8 ± 12.1 yrs) and mean brachial SBP (141 ± 16 vs. 141 ± 17 mmHg) were similar between the DM and non-DM groups. The rAI was significantly lower in the DM group (83.3 ± 14.1 vs. 87.3 ± 15.7%, p < 0.001), but clinic PP (62 ± 14 vs. 59 ± 14 mmHg, p < 0.001) and cPP (51 ± 15 vs. 49 ± 15 mmHg, p = 0.019) were significantly greater in the DM group than in the non-DM group. In multivariable analyses adjusting for covariates, the significant determinants of rAI were the estimated glomerular filtration rate (eGFR) (β = 0.17, p < 0.001) in the DM group, and the log-transformed homeostatic model assessment of insulin resistance (HOMA-IR) (β = -0.15, p < 0.001) in the non-DM group. The same trends were also seen for central SBP and cPP.
  
  
  CONCLUSIONS
  The lower rAI in DM associated with higher cPP compared to non-DM suggests proximal conduit-predominant arterial stiffening causing reduced reflection coefficients at systemic reflection sites. As renal function decreases, a cPP increase may overcome the increase of augmentation pressure in the DM group.
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, Jichi Medical University, Shimotsuke, Japan. Electronic address: ke112@jichi.ac.jp.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Eguchi
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, Jichi Medical University, Shimotsuke, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hoshide
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, Jichi Medical University, Shimotsuke, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miyashita
authors.affiliation: Division of Endocrinology and Metabolism, Department of Medicine, Jichi Medical University, Shimotsuke, Japan.
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Nagasaka
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, Jichi Medical University, Shimotsuke, Japan.
authors.forename: Kazuomi
authors.initials: K
authors.lastname: Kario
mesh_terms: D000368:Aged; D055109:Ankle Brachial Index; D001011:Aorta / Q000503:physiopathology*; D001794:Blood Pressure; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008365:Manometry; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D011446:Prospective Studies; D017534:Radial Artery / Q000503:physiopathology*; D059289:Vascular Stiffness
keywords: Central pressure; Diabetes; Non-diabetes; Radial augmentation index; Renal function