Hemoglobin A1c and C-reactive protein are independently associated with blunted nocturnal blood pressure dipping in obesity-related prediabetes

Blunted nocturnal dipping in blood pressure (BP) is associated with increased cardiovascular disease (CVD) risk in middle-aged/older adults. The prevalence of blunted nocturnal BP dipping is higher in persons with obesity and diabetes, conditions that are also associated with elevated aortic stiffness and inflammation. Therefore, we hypothesized that elevated glycemia, inflammation and aortic stiffness would be inversely associated with the magnitude of nocturnal systolic BP dipping among middle-aged/older adults with obesity at high CVD risk. Twenty-four hour ambulatory BP monitoring, aortic stiffness (carotid-femoral pulse wave velocity, CF-PWV), 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 (age 40-74 years; 34 male/52 female; body mass index = 36.7 +/- 0.5 kg m(-2); HbA1c = 5.7 +/- 0.04%). In the entire cohort, CRP (beta = 0.40 +/- 0.20, P = 0.04), but not HbA1c or CF-PWV was independently associated with systolic BP dipping percent (Model R-2 = 0.07, P = 0.12). In stratified (that is, presence or absence of prediabetes) multiple linear regression analysis, HbA1c (beta = 6.24 +/- 2.6, P = 0.02) and CRP (beta = 0.57 +/- 0.2, P = 0.01), but not CF-PWV (beta = 0.14 +/- 2.6, P = 0.74), were independently associated with systolic BP dipping percent (Model R-2 = 0.32, P < 0.01) in obese adults with prediabetes but were absent in obese adults without prediabetes (Model R-2 = 0.01 P = 0.95). However, nocturnal systolic BP dipping percent (P = 0.65), CF-PWV (P = 0.68) and CRP (P = 0.59) were similar between participants with and without prediabetes. These data suggest that impaired long-term glycemic control and higher inflammation may contribute partly to blunted BP dipping in middle-aged/older adults with obesity-related prediabetes.