While most men assume that it is a physical problem, our research team at the University of Toledo college of medicine and life sciences is finding that proteins in the brain also play an important role in erectile dysfunction, particularly for men with diabetes-related ED. We investigated whether hyperglycemia increases O-GlcNAc modification of eNOS in the penis, preventing phosphorylation at the primary positive regulatory site on the enzyme and hampering mechanisms of the erectile response. Alprostadil is administered by self-injection of the penis, or by inserting a small pellet into the water pipe (urethra) so that the drug can be absorbed by the erectile tissue. Erectile dysfunction was assessed by Sexual Health Inventory for Men questionnaire. You might also need more time between erections. Those with diabetes are at especially high risk because the disease can damage blood vessels. Age, peripheral neuropathy and lower urinary tract symptoms were other risk factors.