Your physician should check your monitor at least once every year. This ensures the accuracy of the measurements. Only a physician knows how to diagnose you with high blood pressure. If your readings are high for several days, contact your doctor. Be sure to take your blood pressure log along with you to the medical visit. If your blood pressure is low, you need to check with your doctor. Being very low blood pressure is life-threatening. If you feel unwell at all, see your doctor straight away.