Diurnal correlation of ambulatory blood pressure and interstitial glucose in patients with normal glucose tolerance.

OBJECTIVE: Among the physiological variables whose diurnal profile is governed by circadian rhythmicity, plasma glucose concentrations, and arterial blood pressure constitute key elements of the physiological regulation of energy homeostasis. Evidence on their diurnal association derived from frequent measurements of both variables is, however, lacking in humans. METHODS: We investigated the relationship between blood pressure levels recorded by an ambulatory device and interstitial glucose concentrations on an outpatient basis, in patients with normal glucose tolerance (N=20), either normotensive (group A; N=10), or newly diagnosed with essential hypertension (group B; N=10). RESULTS: In the population throughout the 24-h monitoring period, there was a significant positive correlation between interstitial glucose concentrations and systolic, diastolic, and mean 24-h blood pressure levels, which was retained in patients with hypertension compared with normotensive patients. In patients with newly diagnosed hypertension, interstitial glucose concentrations exhibit significant correlation to systolic blood pressure levels during the 24-h period, but no association with diastolic and mean blood pressure during the night, whereas the reverse is the case in patients with normal glucose tolerance and normal blood pressure. CONCLUSION: Diurnal variations of continuously monitored interstitial glucose concentrations significantly associate with blood pressure levels in both normotensive and hypertensive humans, indicating a common pathway of circadian autoregulation, probably stemming from both central mechanisms and peripheral inputs. Such a pathway might underlie similar pathophysiological aberration in disease states such as the metabolic syndrome.

Factors influencing white-coat effect.

BACKGROUND: The transient blood pressure (BP) rise during clinical visits is usually referred to as white-coat effect (WCE). The aim of the present study was to investigate factors that may influence the WCE. METHODS: A total of 2004 subjects underwent office BP measurements and 24-h ambulatory BP monitoring (ABPM) on the same day. The WCE was estimated as the difference between office and average daytime ambulatory BP (ABP). According to the office and daytime BP values, the study population was divided into normotensives (NTs), white-coat hypertensives (WCHs), masked hypertensives (MHTs), and sustained hypertensives (SHTs). Statistical analyses were performed using one-way analysis of variance and multiple linear regression models. RESULTS: The mean systolic and diastolic WCE was 9 +/- 16 and 7 +/- 12 mm Hg, respectively. In the entire group of patients, multiple linear regression models revealed independent determinants of systolic WCE in the following rank order: office systolic BP (SBP) (beta = 0.727; P < 0.001), female gender (beta = 0.166; P < 0.001), daytime SBP variability (beta = 0.128; P < 0.001), age (beta = 0.039, P = 0.020), and smoking (beta = 0.031, P = 0.048). A 1.0 mm Hg increase in daytime SBP variability correlated with an increment of 0.589 mm Hg (95% confidence intervals, 0.437-0.741) in the systolic WCE. The regression analyses for diastolic WCE revealed the same factors as independent determinants. A 1.0 mm Hg increase in daytime diastolic BP (DBP) variability was independently associated with an increment of 0.418 mm Hg (95% confidence intervals, 0.121-0.715) in the diastolic WCE. CONCLUSIONS: Factors such as gender, age, smoking, office BPV and daytime BPV may exert an important influence on the magnitude of the WCE.