One risk factor is advancing age. According to the American Urological Association (AUA), as men age, the level of circulating testosterone decreases, which may interfere with normal erection. While a low testosterone level itself is rarely the cause of ED, low testosterone can be an additional contributing factor in many men who have other risk factors for ED. Other risk factors for ED include various medical problems, such as hypertension (abnormally high blood pressure), diabetes, vascular disease, and high levels of blood cholesterol. Smoking and drug and alcohol abuse also are risk factors for ED.