Normally high blood pressure, suddenly low blood pressure mainly has the following conditions: 1, check whether the antihypertensive drugs taken too much, or repeatedly taken; 2, consider whether there is the possibility of postprandial hypotension, many elderly people have the phenomenon of postprandial hypotension; 3, there are changes in the condition. Many diabetic patients will occur painless heart attack, no typical symptoms of heart attack, such as chest suffocation, chest pain, pain in the precordial region are not, and suddenly the blood pressure drops too low or below normal, be alert to the possibility of having an acute heart attack, especially extensive anterior wall heart attack. This situation should be promptly consulted and call 120 in a timely manner.4. It may also be due to excessive sweating, diarrhea, eating less, etc.