Two new studies say that erectile dysfunction (ED) may be a warning sign of diabetes, as well as a warning of approaching cardiovascular disease.

ED, the inability to achieve or maintain a sturdy penile erection, affects more than 50 percent of all American men from the ages of 40 to 70. Scientists used to think that it was primarily a psychological problem, but now believe that it is the result of poor blood flow to the penis.

In the case of both diabetes and cardiovascular disease, the concern is that ED is a symptom of impeded blood flow that can later lead to heart attack or stroke. But men with diabetes face a higher risk of developing cardiovascular disease than men who have ED alone, suggest two studies published in the Journal of the American College of Cardiology.

One of the studies, conducted in Italy, tracked diabetic men who had symptomless coronary artery disease over four years. Those who had ED before entering the study were more likely to experience a major cardiac event, such as a heart attack, than those who entered the study without ED.

Among those affected by ED, 61.2 percent had a major heart problem during the study, compared with 36.4 percent of men without ED.

The second study, also four years long, tracked 2,306 men in Hong Kong who had diabetes but no cardiovascular problems. It found that men who also had ED ran about a 60 percent higher risk of developing cardiovascular problems.

The study’s author, Peter Tong, a professor at Chinese University of Hong Kong, said that even mild ED in men with diabetes could indicate highly abnormal glucose, blood pressure and lipid levels.

Doctors recommend that men with diabetes who are experiencing ED should immediately see a physician to be tested for vascular disease. They should also discuss medications – among them, Viagra, Levitra, Cialis and statins – that can restore penile function and lower the risk of heart problems.

In the meantime, doctors make standard recommendations for thwarting and dealing with ED that most men with diabetes already know:

• Get exercise
• Don’t smoke
• Eat a healthy diet