The impact of body mass index on blood pressure measured with mercury sphygmomanometer in children and adolescents with type 1 diabetes mellitus

Background: Patients with type 1 diabetes mellitus (T1DM) and overweight have more risk to develop changes in blood pressure that increase cardiovascular morbidity and mortality. In this study, the relationship between blood pressure (BP) with the body mass index (BMI) and the average of the last three measurements of glycated hemoglobin (HbA1c) in patients with T1DM was determined. Methods: A cross-sectional analytical study was conducted in children and adolescents with T1DM with over a year since diagnosis. The dependent variables were systolic and diastolic BP, measured with a mercury sphygmomanometer. The independent variables were BMI and average of the last three measurements of HbA1. A linear regression with a 95% confidence interval was used. Results: Seventy-five patients with T1DM were studied. The median of disease duration was 3.5 years (min 1-max 14.8 years), BMI 19.5 +/- 3.1 kg/cm(2) and HbA1c 8.3 +/- 2.4%. Sixty-six patients showed BP < percentile 90 and 9 BP >= percentile 90 (12%). Two models of linear regression were constructed, with systolic and diastolic BP as dependent variables. The possible predictor variables were suggested by theoretical context and statistical analysis. The predictive variable of high BP was zBMI (body mass index expressed in z-score) for systolic and diastolic BP. Also, the models suggested that for an increase of one unit of zBMI, corresponded a rise of 5.1 and 3.6 mmHg in systolic and diastolic BP, respectively. Conclusions: A positive correlation between systolic and diastolic BP with zBMI was observed.