Assessment of vascular function in individuals with hyperglycemia: a cross-sectional study of glucose - induced changes in digital volume pulse

Abstract

Background: Arterial stiffness is an independent risk factor for cardiovascular disease and its progression may be accelerated in the presence of hyperglycemia, either fasting or postprandial. The current study assessed vascular function in subjects with pre-diabetes hyperglycemia, using digital volume pulse analysis technique.

Methods: We conducted a cross-sectional study examining vascular function in the fasting and postprandial (glucose-induced) state in 44 adults, consisting of 17 subjects with pre-diabetic hyperglycemia and 27 normoglycemic volunteers. Photoplethysmography of the digital volume pulse (DVP) was used to determine stiffness index (SI) and reflective index (RI), as main measures of larger artery stiffness and vascular tone, respectively.

Results: Our results showed a significantly higher (Ln) fasting SI in the hyperglycemic group compared with the control group (2.19 ± 0.32 vs. 1.96 ± 0.22, P = 0.005). However, this pattern reversed after adjustment for potential confounders. In multiple linear regression analysis, (Ln) SI was related to age (β = 0.01, 95% CI: 0.01-0.02, P < 0.001) and systolic blood pressure (SBP) (β = 0.01, 95% CI: 0.00-0.01, P < 0.05), but not with W/H, diastolic blood pressure (DBP), fasting plasma glucose (FPG) or serum lipids. Furthermore, age (β = 0.02, 95% CI: 0.01-0.03, P < 0.001) and mean arterial pressure (MAP) (β = 0.01, 95% CI: 0.00-0.02, P < 0.05) were found as the strong predictors of fasting SI in hyperglycemic group. Neither FPG nor 2-h plasma glucose was a significant predictor for SI in hyperglycemic group, after accounting for age and MAP. Subjects with hyperglycemia had a 15% blunted change in postprandial AUCs for RI, adjusted for the respective baseline measurements (-9.40 ± 3.59 vs. -11.00 ± 2.84%) but these did not attain statistical significance.

Conclusion: Increased arterial stiffness in pre-diabetic subjects is strongly associated with age and MAP. The increased DVP-derived SI reported in patients with pre-diabetic hyperglycemia may result from different frequently accompanied risk factors not just glycemic changes in this range.

Keywords: Arterial stiffness; Digital volume pulse analysis; Hyperglycemia; Photoplethysmography; Reflection index; Stiffness index.

Figure 1

Indices derived from digital volume pulse analysis. SI, stiffness index; RI, reflection index; PPT, peak-to-peak time.

Figure 2

Log-transformed fasting SI without adjustment (a); and Log-transformed fasting SI, after adjusting for age, sex, SBP, DBP and W/H, (b) determined in normal and hyperglycemic groups. Data are presented as mean ± SEM. *, p < 0.01 compared to the normal control group.

Figure 3

Changes in the post-glucose challenge RI observed in normal and hyperglycemic groups. Data are presented as mean ± SEM of the change in the postprandial AUC from the baseline, and are adjusted for the baseline measurements. *, p < 0.05 compared to the normal control group.