Quantitative study of circadian variations of ambulatory blood pressure in Chinese healthy, hypertensive, and diabetes subjects.

Ambulatory blood pressure monitoring (ABPM) recorded abundant data of BP and heart rate (HR) variations with even more derived parameters for evaluation of BP. Using our ABP database system established recently, we studied quantitatively the data of 24-hr ABP in Chinese. First, 155 Chinese were divided into three groups: 50 healthy subjects (C) of 20 men and 30 women, aged 60.0 +/- 10.3 (SD) years; 58 hypertensive patients (H, mild or moderate hypertension) of 33 men and 25 women, aged 59.4 +/- 8.0 years; 47 diabetes patients (D, type 2 diabetes, all were normotensive and with no insulin treatment) with 28 men and 19 women, aged 61.0 +/- 8.5 years. Then 24-hr ABP was monitored by TM-2421 Monitor and data were analyzed by ABP database, cosinor method, and conventional statistics. Our results were 4-fold: 1) systolic BP (SBP), diastolic BP (DBP), HR, rate-pressure product (HR x SBP) showed circadian variations, and significant circadian rhythms were confirmed by cosinor method in all groups. MESOR (midline estimate statistic of rhythm) differed significantly among three groups (H had the highest and C had the lowest values); 2) BP means (SBP, DBP, pulse pressure [PP], and HR x SBP) and BP loads (SBP, DBP, and PP) showed significant differences among the groups (H and D had higher values than that of C); 3) there were no significant differences of BP variability (BPV) of SBP, DBP, and PP among the groups; 4) areas under curve of BP (SBP, DBP, and PP) in H were significantly higher than in C and there was no significant difference between H and D. We concluded that ABPM can offer abundant information on BP evaluation by its direct recording data and derived parameters. The computerized way of treating the large numbers of ABPM values supplies a useful tool in evaluation of BP. Our results suggest that clinically normotensive diabetes patients had some pathological alterations in their BP systems.