The higher the blood pressure, the higher the chance of developing cardiovascular disease.
Blood pressure is expressed as a fraction.
Both numbers are important. Systolic blood pressure tends to increase with advancing age. Diastolic blood pressure tends to increase in young adulthood and plateau during middle age. Diastolic hypertension is a common disease with 25 percent of the adult American population suffering from it. The causes of hypertension remain unknown, and there is no certain way of knowing which persons are at increased risk of developing hypertension.