Non-Dipping and Cardiometabolic Profile: A Study on Normotensive Overweight Middle-Aged Men

Abstract

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 (-5.0 mmHg; p = 0.022) and diastolic (-3.3 mmHg; p = 0.035) blood pressure than dippers. Conversely, during sleep, non-dippers had higher systolic (+6.5 mmHg; p = 0.003) and diastolic (+5.6 mmHg; 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 820 μm; 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.