June 2019

In healthy adults, blood pressure (BP) decreases during sleep at night to lower levels than during the daytime. This phenomenon is referred to as nocturnal BP “dipping” and normally dips 10-20% compared with daytime. Blunted nocturnal BP dipping has been independently associated with increased cardiovascular disease (CVD) risk. The prevalence of blunted nocturnal BP dipping is higher in persons with obesity and diabetes, which are traditional risk factors for CVD.  Aortic stiffness and inflammation are emerging as novel CVD risk factors, but whether there is an association between these factors and nocturnal BP dipping has not been well-described. The team of FOEDRC member Gary Pierce, that was led by Dr. Abbi Lane-Cordova, hypothesized that evidence of poor glucose control, inflammation and aortic stiffness would be inversely associated with the relative magnitude of nocturnal systolic BP dipping among middle-aged/older adults with obesity at elevated CVD risk. 
Twenty-four hour ambulatory BP monitoring, aortic stiffness (carotid-femoral pulse wave velocity, CF-PWV), glucose control characterized by hemoglobin A1c (HbA1c) and inflammation (C-reactive protein, CRP) were measured in 86 middle-aged/older adults with obesity and at least one other CVD risk factor. The age of study participants ranged from  40-74 years and included 34 men  and 52 women and 50 had prediabetes.
The major predictor of  impaired nocturnal blood pressure dipping In the entire cohort of 86 adults was the circulating concentrations of CRP. In individuals with prediabetes, HbA1c (a measure of glucose control) and CRP were independently associated with systolic BP dipping percent in obese adults with prediabetes. There were no significant associations in obese adults without prediabetes, even though nocturnal systolic BP dipping percent, CF-PWV, and CRP were similar between participants with and without prediabetes. 
These data reveal abnormal control of systolic BP dipping in adults with obesity and prediabetes. They indicate that even before diabetes is diagnosed in men and women who are overweight and at increased risk of developing diabetes, there is evidence of whole body inflammation that may contribute to blunted BP dipping. Thus cardiovascular health is already significantly impaired  in high-risk individuals before diabetes is diagnosed. These findings were published in the Journal Hypertension Research.