Non-Dipping and Cardiometabolic Profile: A Study on Normotensive Overweight Middle-Aged Men.
BACKGROUND
We aimed to assess insulin sensitivity and other metabolic features of dippers and non-dippers among overweight middle-aged men.


METHODS
We studied 73 men (45.8 ± 5.3 years) who were overweight but normotensive. Participants were separated into dippers and non-dippers based on the magnitude of the nocturnal decline of blood pressure, with dippers experiencing an overnight decline ≥10% as per standard definition. Our study included 51 dippers and 22 non-dippers. All participants underwent 24-hour ambulatory blood pressure monitoring. Insulin sensitivity was assessed by the Matsuda method from an oral glucose tolerance test; other assessments included carotid artery intima-media thickness (CIMT), body composition derived from dual-energy X-ray absorptiometry, lipid profiles, and a physical activity questionnaire.


RESULTS
Non-dippers had lower daytime systolic (-5.0mmHg; p=0.022) and diastolic (-3.3mmHg; p=0.035) blood pressure than dippers. Conversely, during sleep, non-dippers had higher systolic (+6.5mmHg; p=0.003) and diastolic (+5.6mmHg; p=0.001) blood pressure. In continuous associations, increasing CIMT was associated with decreasing systolic (p=0.012) and diastolic (p=0.042) dipping. Thus, non-dippers had CIMT that was 9% greater than that of dippers (749 vs 820μm; p=0.036). Importantly, there was no association between non-dipping status or the magnitude of the nocturnal dip with insulin sensitivity.


CONCLUSIONS
Non-dippers had lower blood pressure in the daytime, but higher blood pressure in the night time compared to dippers. Non-dippers had increased CIMT, which suggests that normotensive men with a non-dipping ambulatory blood pressure profile may be at increased cardiovascular risk. However, it appears that the non-dipping profile is unrelated to dysfunction of glucose homeostasis in overweight normotensive men.
Liggins Institute, University of Auckland, Auckland, New Zealand.
Benjamin B
BB
Albert
Liggins Institute, University of Auckland, Auckland, New Zealand.
Martin
M
de Bock
Liggins Institute, University of Auckland, Auckland, New Zealand.
José G B
JG
Derraik
Liggins Institute, University of Auckland, Auckland, New Zealand.
Christine M
CM
Brennan
Liggins Institute, University of Auckland, Auckland, New Zealand.
Janene B
JB
Biggs
Liggins Institute, University of Auckland, Auckland, New Zealand; Gravida: National Centre for Growth and Development, Auckland, New Zealand.
Paul L
PL
Hofman
Liggins Institute, University of Auckland, Auckland, New Zealand; Gravida: National Centre for Growth and Development, Auckland, New Zealand. Electronic address: w.cutfield@auckland.ac.nz.
Wayne S
WS
Cutfield
D015502:Absorptiometry, Photon; D000328:Adult; D018660:Blood Pressure Monitoring, Ambulatory; D059168:Carotid Intima-Media Thickness; D015444:Exercise; D006801:Humans; D007333:Insulin Resistance; D008055:Lipids / Q000097:blood*; D008297:Male; D008875:Middle Aged; D050177:Overweight / Q000097:blood / Q000000981:diagnostic imaging / Q000503:physiopathology; D011795:Surveys and Questionnaires
D008055:Lipids
Carotid artery intima-media thickness; Diastolic; Dipping; Insulin sensitivity; Systolic