24-hour blood pressure homeostasis and renal function in subjects with and without metabolic syndrome

Materials and methods We designed a cross-sectional study of consecutive individuals (n=108; females 74%; 52.8±12.7 yrs.; mean±SD) from the Diabetes Clinic of a university hospital. MS was defined by the International Diabetes Federation criteria. BP was measured at office and its circadian variation was determined by 24-h ambulatory BP monitoring, after withdrawal from anti-hypertensive medications. Patients were classified according to their BP behavior: normotension (NT; n=29), white-coat hypertension (WCH; n=19) and ambulatory hypertension (AHT; n=57). Fasting and 2h-plasma glucose levels, lipid profile, creatinine and 24-h urinary albumin excretion (UAER) were measured. Glomerular filtration rate (GFR) was estimated by the CKD-EPI equation. A two-sided P value <0.05 was considered significant. Results Estimated GFR (EGFR) was lower in subjects with MS than in those without MS (Mean±SD; 90±20 vs 98.8±16.5; P=0.047). EGFR was related to age (r=-0.666; P<0.001), fasting glucose (r=0.223; P=0.021), and 24-h systolic BP (r=-0.196; P=0.044), but not to diastolic BP. EGFR was inversely related to sleep-time BP (r=-0.224; P=0.021), morning systolic BP (r=-0.224; P=0.030) and pulse pressure (r=-0.233; P=0.170). Subjects with WCH and AHT compared to those with NT had lower EGFR (Mean±SD; 89.3±18 vs 89.6±26.3 vs 100.2±14.8; P=0.036) and higher UAER (Median [P25-75]; 1 [0-5.3] vs 6.1 [1-19] vs 6.3 [1-16.8]; P=0.031).