Rosiglitazone effects on blood pressure and metabolic parameters in nondipper diabetic patients.

The class of antidiabetic drugs called thiazolidinediones (TZD), possesses as its main feature, the ability to ameliorate insulin sensitivity. As diabetes and hypertension share common ground in insulin resistance, the aim of this study was to evaluate if Rosiglitazone (RSG) may exert antihypertensive properties. Diabetic patients selected for the study were free from complications and/or other diseases. They were not known hypertensives, not on any antihypertensive treatment and they were on up to 2550 mg of metformin per day. Twenty-four hour blood pressure (24-h BP) measurements were recorded and monitored. Thirty-eight patients with a nocturnal decline in BP less than 10% (nondippers) participated in the study. Patients were randomly assigned to metformin+placebo (19 patients: group A) or to metformin+RSG 4 mg b.i.d. (19 patients: group B). Patients from both groups continued to take the same dosage of metformin during the study period. After 12 months of treatment, 24-h BP measurements were recorded. Fasting blood glucose, insulin, HbA1c, total cholesterol and trigliceryde levels were taken at the beginning and again at the end of the study. After 12 months of treatment with RSG+metformin we observed an amelioration of metabolic parameters (reduction of HOMA index, glucose, insulin, HbA1c, total cholesterol and triglycerides); an increase in body weight and BMI; a significant reduction of systolic and diastolic BP values both during the day and night and variations in the HOMA index were positively related to the reduction of diurnal and nocturnal BP (HOMA index versus diurnal systolic BP (P<0.001; r2=0.727); versus diastolic BP (P<0.001; r2=0.757); versus nocturnal systolic BP (P<0.001; r2=0.842), versus diastolic BP (P<0.001; r2=0.773)). These findings indicate firstly that RSG is able to induce a reduction of BP and secondly the amelioration of insulin sensitivity is associated with the reduction of BP.