Contributors of abnormal 24-h systolic blood pressure in type 1 diabetes families

Background: Oxidative damage is increased in families of type 1 diabetics (T1D) and normotensive non-diabetic relatives of T1D have an abnormal blood pressure response to exercise testing that is associated with indices of metabolic syndrome and oxidative damage. We evaluated the pattern of 24-h ambulatory blood pressure (BP) monitoring (ABPM) in T1D families and its relationship with clinical parameters and oxidative biomarkers. Materials and methods: A cross-sectional study was conducted in 25 control subjects (46 ± 12 year; BMI 24 ± 3), 21 T1D (45 ± 10; 25 ± 4) and 21 non-diabetic siblings of T1D (46 ± 10; 26 ± 5, P < 0Æ05 vs. controls) using an oscillometric device. In addition to routine laboratory investigations, we measured the rate of oxidant-induced erythrocyte electron transfer to extracellular ferricyanide (RBC vfcy) that supplies electrons (from intracellular electron donors) to reduce extracellular oxidants. Results: Twenty-four hour systolic BP differed among groups: 121 ± 7 mmHg in controls, 134 ± 12 in T1D, and 127±13 in siblings (P < 0Æ001). Daytime systolic BP was higher in T1D (137 ± 13 mmHg) and siblings (132 ±13) than in controls (125 ± 7, P < 0Æ001), whereas night-time systolic BP was increased only in T1D 122 ± 17 (107 ± 10 in controls and 109 ± 15 in siblings, P < 0Æ01). Daytime systolic BP of non-diabetic subjects was positively correlated with BMI and RBC vfcy (r = 0Æ62, P < 0Æ001). Conclusions: ABPM data confirm that non-diabetic siblings of T1D patients have abnormal systolic blood pressure during daytime. An index of fat body mass (BMI) and erythrocyte plasma membrane oxidoreductases seem to be important contributors to the development of borderline systolic BP in relatives of T1D patients.