short answer: he might be suffering from erectile dysfunction or lack of energy and hormonal changes if it is so he can use viagra which will increase the blood flow to the penis detailed answer: The most widely reported problem men face is erectile dysfunction. In fact, in some cases diabetes is diagnosed when the man seeks treatment for erection dysfunction—erectile dysfunction is a presenting symptom of diabetes, particularly for those under 45 years of age. Failure to achieve or maintain an erection until ejaculation can be caused from nerve, muscle, or vascular damage. It is estimated that between 20 and 75% of men will have a problem with erectile dysfunction. . Changes in testosterone level can also affect erection, as can sexual side effects of medication. Did you know sometimes using a vibrator could help with neuropathy and increase stimulation? This is true for both men and women, although it can take several uses before a change is noticed. Consider getting a small vibrator and applying it to areas where you experience neuropathy for a few minutes each day.