A recent population based study found that ED is not as uncommon in young men as previously thought.  Perhaps 7% of men under the age of 30 are affected. As with all categories of ED patients, the key is to obtain a detailed medical history provided by the patient in a non-threatening environment. 

While many cases of ED in young men have a psychogenic causes, ie. depression or anxiety, other causes including diminished testosterone blood levels and diabetes can be uncovered with simple lab tests.
 
As you might guess, the ED drugs are highly effective and safe in treating this population of men with ED.