This study found that CBP is a clinically significant predictor for primary endpoints, showing a U-shaped association of CBP and risk of CV events in T2DM. The lowest incidence of primary endpoints was seen at CBP of 118 mmHg and SBP of about 128 mmHg.
A previous large cohort study reported an association of SBP and risk of CV events and mortality, with a U-shaped curve pattern in T2DM [8], and SBP was found to have the lowest incidence at 135–139 mmHg the manual Korotkoff method or automatic measurement. In a study conducted in the general population [18], CBP had a threshold of 112 mmHg and SBP of 121 mmHg when a digital automatic BP monitor was used; however, the study did not show a U-shaped pattern. The CBP of 118 mmHg and SBP of 128 mmHg found in our study of the T2DM population are more stringent than those used in previous studies of T2DM patients (SBP, 135–139 mmHg) and are less intensive than those in the general population (CBP, 112 mmHg and SBP, 121 mmHg), which might require more tight objectives than previously considered by T2DM patients. However, in comparison with the general population, optimal CBP in T2DM patients can suggest increased risk of CV events. These assumptions are confirmed as a result.
In the result, risk ratio to an increase in CBP of 10 mmHg. As a result, this study suggests that after 6.5 years of follow-up, the risk of CVA increases by 14% for every 10 mmHg increase in CBP (HR, 1.14 P = 0.016).
In addition, previous studies suggested that there is a limitation in providing accurate information about the patient's BP status due to the problem of variability in peripheral BP. Although somewhat cumbersome, noninvasively measured central pulse pressure is more strongly associated with vasoconstriction, severity of atherosclerosis, and CV events than BBP as is known from the Strong Heart Study. Therefore, it is thought that measuring CBP may be important in assessing each patient's CV risk in order to more accurately determine the patient's BP status. So optimal CBP setting is more important in T2DM patients than general population.
A previous study conducted in the general population confirmed an increase in SBP in a cascading manner as CBP increased [19] and showed that CBP levels overlap significantly in hypertensive patients classified as SBP. In this study, SBP was increased stepwise in CBP in the T2DM population, suggesting that patients currently classified as hypertensive and receiving the same treatment might need better control through CBP measurement. A mechanism that explains the CBP and CV events in T2DM has been proposed. CBP is a stronger stimulus for LVH than is peripheral BP. Aortic stiffness also might be associated with carotid flow index, which contributes to altered flow dynamics resulting in increased CV risk [20]. In addition, T2DM patients are exposed to CV risk factors including hyperglycemia, advanced glycation end products, and diabetes duration [21], which lead to increased risk of CVA in T2DM. A meta-analysis also showed that markers of central systolic load were significantly increased in T2DM compared to those without T2DM, which could not be identified by BBP [5]. This difference might be associated with demographic or physiologic factors including age, sex, BMI, heart rate, and antihypertensive medication [15, 22].
Postmenopausal female patients showed a greater risk of study end point than male patients. These findings were similar to a study conducted in the Korean population, confirming that central PP tended to be higher in men before 3847 years of age, but the slope was steeper in women than in men at later ages [23]. This is thought to be due to the vascular protective effect of estrogen, as confirmed in previous studies [24], but cannot be explained simply by hormones as some studies suggest that risk is greater than benefit [25].
This study has several limitations. First, the study design is observational and retrospective; consequently, we could not control all confounding factors that affect ASCVD events or hypertension-induced complications. We attempted to adjust confounding factors to reduce this effect. Second, this study included only Korean subjects. In addition, the normal range or cutoff value of CBP has not been confirmed. This study also has plausible strengths in that it is the largest study of CBP measurement, CV events, and hypertension-induced complications and was conducted with long-term follow-up in patients with T2DM.