Differences in circadian time structure of diastolic blood pressure between diabetes mellitus and essential hypertension

We retrospectively evaluated ambulatory blood pressure monitoring records in 30 NT, 20 T1D, 20 T2D, 20 HT whose fasting plasma glucose and HbA1c were contemporaneously measured. The four groups were well-matched regarding age, gender, and BMI.Systolic blood pressure (SBP) and DBP midline-estimating statistic of rhythm were higher in T1D, T2D, and HT groups. DBP ecphasia was present only in the diabetic individuals: the acrophase of DBP occurred four hours earlier than normal in T1D group, whereas two hours earlier in T2D group. In a multiple regression analysis, only HbA1c and SBP acrophase were statistically significant correlates of DBP acrophase.People with diabetes mellitus, both type 1 and type 2, have their circadian acrophase of DBP occurring 2–4 hours earlier than normotensive and hypertensive subjects. Altered circadian timing of DBP, potential trigger of cardiovascular events, seems to be a distinguishing feature of diabetes mellitus and correlates with the previous 2–3 months of glycaemic control.Abnormal patterns of circadian blood pressure (BP) variation, evaluated by ambulatory blood pressure monitoring (ABPM), predict cardiovascular prognosis in diabetes mellitus [1]. We have previously described that the acrophase of diastolic blood pressure (DBP), i.e. the time of the maximum of the DBP, registered in type 1 diabetes (T1D) patients occurred significantly earlier than normal and DBP ecphasia (altered circadian timing) was more pronounced in patients with lower heart rate (HR) variability during deep breathing [2]. Several mechanisms could be involved in linking diabetes mellitus with changes in circadian rhythms of BP and HR, such as interactions between metabolism and circadian gene network [3,4], suppressed clock gene oscillations in vasculature [5], or insulin-melatonin antagonism [6]. However, phase shift in acrophase of DBP has never been specifically addressed. The aims of this study were: 1) to compare the circadian rhythm characteristics of B