[Blood pressure volatility--a new parameter for determining blood pressure variability in type-1 diabetes mellitus]

In diabetes the heart rate variability is decreased because of the autonomic neuropathy and parallel with this phenomenon the overnight blood pressure fall is lost. Presumably this change in the hemodynamic parameters is connected with the fact that the cardiovascular complications in type 1 diabetic patients are 2-4 times more frequent than in healthy patients. The volatility, as a new factor, is the dispersion of the proportion of the blood pressure values following each other. It exactly reflects the 24-hour blood pressure fluctuation, while the dipper/non-dipper determination differentiates only between the daytime and night-time average blood pressure values. The volatility follows the changes of the measured values in accordance to the frequency of the measurements during the whole day.

Our aim was to compare the blood pressure variability of type 1 diabetic patients (DM) and healthy controls (C).

The authors examined 43 diabetic patients from our outpatient clinic and 45 healthy people. The blood pressures were measured with Meditech ABPM 02 monitor on workdays. The measurements started in the mornings. The frequency of the measurements was 20 minutes during the day and 50 minutes at night-time. The authors took the history of all the patients and detailed laboratory results. The patients also had ophthalmology examination, ECG and echocardiography tests.

During the Ambulatory Blood Pressure Monitoring we found that the systolic volatility of blood pressure values was significantly lower in DM compared to C patients. Systolic volatility: 0.133 +/- 0.011 vs. 0.175 +/- 0.014 p < 0.026. Comparing only the normotonic C and DM group systolic volatility of blood pressure values were significantly lower in DM. Systolic volatility: 0.128 +/- 0.016 vs. 0.177 +/- 0.021 p < 0.036.

It is an important new finding that in type 1 diabetic patient the volatility--a new parameter for determining blood pressure variability--is lower than in the healthy control group. At normotension state other parameters describing the blood pressure variability (like diurnal index or standard deviation) could not show this change.