Glucose abnormalities associated with impaired nocturnal fall in blood pressure in normotensive severely obese patients

Abstract

Background: The purpose of this study was to identify factors affecting the nocturnal decline in blood pressure (BP) in severe obesity.

Methods: Clinical, biochemical, polysomnographic data, glucose tolerance status, and body fat composition were obtained in 82 candidates for bariatric surgery (mean age: 40 (11) years; BMI: 46 (4)kg/m(2)). To determine the nocturnal BP fall we used 24-h ambulatory BP monitoring to measure the magnitude (Δ) of nocturnal decline, the % day-night systolic BP (SBP) and diastolic BP (DBP), dipper status and nocturnal hypertension (HT).

Results: Twenty-three percent of patients had nocturnal HT. Sixty percent had non dipper status, of which 95% had nocturnal HT. No specific factors were associated with the average 24-h SBP and DBP. Having glucose abnormalities was of primary importance for all variables evaluating nocturnal BP decline independent of daytime BP levels and severity of obesity. In comparing patients with or without glucose tolerance abnormalities, the night-time SBP and DBP were significantly higher and the Δ nocturnal decline and % day-night in both SBP and DBP were significantly lower in those with glucose tolerance abnormalities. In an adjusted multivariate model, having both glucose abnormalities and nocturnal HT remained associated with non dipper status with an OR of 3.13 (95% CI 1.11-8.87, p=0.03) and 14.93 (95% CI 1.77-125.62, p=0.001), respectively.

Conclusion: In normotensive severely obese patients, non dipper status and nocturnal HT are common, and the presence of glucose abnormalities was the primary variable associated with impaired nocturnal fall in BP.

Keywords: Bariatric surgery; Circadian blood pressure; Dipper status; Normotension; Severe obesity.