Higher Hemoglobin A1c and C‐Reactive Protein but not Aortic Stiffness are Independently Associated with Blunting of Nocturnal Systolic Blood Pressure Dipping Among Middle‐Aged/Older Adults with Obesity and Prediabetes
Authors: Sindler Amy L , Kalil Graziela Z , Wagner Christopher J , Lane‐Cordova Abbi , Fiedorowicz Jess G , Haynes William G , Pierce Gary L 
Published: November 2023

Nighttime systolic blood pressure (BP) typically decreases 10–20% compared with daytime systolic BP (determined by 24‐hour ambulatory blood pressure monitoring)‐ a phenomenon referred to as nocturnal BP “dipping.” A blunted decrease (i.e., <10%) in nocturnal systolic BP, known as “non‐dipping”, is associated with aortic stiffness, left ventricular hypertrophy and cardiovascular disease (CVD) events in adults with and without hypertension. Obesity‐related prediabetes is associated with an increased risk of CVD in part through increased aortic stiffness and systemic inflammation. However, it is unknown whether the presence of prediabetes in adults with obesity blunts BP dipping and if elevated aortic stiffness and inflammation are associated with nocturnal BP dipping in this group. We hypothesized that middle‐aged/older adults with obesity‐related prediabetes would demonstrate less nocturnal systolic BP dipping than non‐prediabetic obese adults and would be associated with greater aortic stiffness and systemic inflammation. Middle‐aged/older adults with obesity (n=99; age=40–74 yrs; 35M/64F; body mass index, BMI ≥ 30 kg/m2) and prediabetes, defined as glycosylated hemoglobin A1c (HbA1c) ≥ 5.7–6.5%, had assessments for 24 hour ambulatory BP monitoring, inflammation (serum c‐reactive protein, CRP) and aortic stiffness (carotid‐femoral pulse wave velocity, CF‐PWV). There were no differences in nocturnal % systolic BP dipping (−10.3 ± 0.8% vs. −10.2 ± 0.9%, P=0.98), CF‐PWV (9.3 ± 0.3% vs. 9.2 ± 0.3%, P=0.72) or CRP (4.2 ± 0.5 vs. 3.6 ± 0.3 mg/L, p=0.46) between prediabetic (n=58; age=58 ± 1 yrs; BMI=37.1 ± 0.7 kg/m2; HbA1c=6.0 ± 0.3%) and non‐prediabetic (n=41; age=53 ± 1 yrs; BMI=36.6 ± 0.8 kg/m2; HbA1c=5.4 ± 0.2%) obese adults. Among the adults with prediabetes, less nocturnal % systolic BP dipping was associated with higher HbA1c (r=0.26, P=0.05), log CRP (r=0.41, P<0.01) and 24‐hour systolic BP (r=0.31, P=0.02), but not CF‐PWV (r=0.09, P=0.51). In multiple linear regression modelling that included age, sex, BMI and total 24‐hour systolic BP, only HbA1c (β= 6.04 ± 2.6, P=0.02) and log CRP (β= 6.34 ± 2.26, P<0.01) independently predicted nocturnal % systolic BP dipping (Model R2=0.32, P<0.01) in adults with obesity and prediabetes. Conversely, in obese adults without prediabetes, nocturnal % systolic BP dipping was not associated with HbA1c, CRP or CFPWV. These data suggest that impaired glycemic control and higher inflammation may be potential mechanisms that contribute in part to blunted nocturnal systolic BP dipping and increased risk of CVD in middle‐aged/older adults with obesity and prediabetes.Support or Funding InformationSupported by NIH grants 5T32 HL007638‐28, 5T32 HL007121‐3, U54 TR001013, 5 KL2 RR24980‐5, 2P01 HL014388, 1K01 AG047626, 1R21 AG043722 and AHA 13SDG143400012