ED may occur with or without other sexual dysfunction, including decreased libido (decreased interest in sexual activity), orgasmic dysfunction (troubles achieving an orgasm/climax), and ejaculatory dysfunction (problems with the fluid released during sex, including lack of ejaculation [anejaculation], small volume ejaculate, ejaculation that occurs too quickly [premature ejaculation], ejaculate that goes backward into the bladder [retrograde ejaculation] and pain with ejaculation).
Diabetes is a well-recognized risk factor for ED. A systematic review and meta-analysis found that the prevalence of ED was 37.5% in type 1 diabetes, 66.3% in type 2 diabetes, and 52.5% in diabetes overall—a rate approximately 3.5 times higher than that in controls.  The etiology of ED in diabetic men probably involves both vascular and neurogenic mechanisms. Evidence indicates that establishing good glycemic control can minimize this risk.
Alteration of NO levels is the focus of several approaches to the treatment of ED. Inhibitors of phosphodiesterase, which primarily hydrolyze cGMP type 5, provided the basis for the development of the PDE5 inhibitors. Chen et al administered oral L-arginine and reported subjective improvement in 50 men with ED.  These supplements are readily available commercially. Reported adverse effects include nausea, diarrhea, headache, flushing, numbness, and hypotension.
Neurologic impotence is suggested by the absence of sensation in the sacral dermatomes when tested by pinprick, or by neurologic abnormalities elsewhere. The bulbocavernosus reflex may be assumed to be present if anal sphincter tone is normal on rectal examination. If there is doubt, the reflex can be tested by pinching the glans penis and assessing sphincter contraction during the rectal examination.
For more information please refer to the erectile dysfunction article. There are also other causes of problems in bed like enlarged prostate, or you may be interested in general male enhancement. This is not the subject we are talking about. The main purpose of this review is to let you know how to get an erection when you need it. We will take a look at the products and techniques that will help you get an instant erection on demand. Face it, if you want to take total control of a woman, you just can't let concerns about your performance disrupt the thrill and momentum of spontaneous, passionate sex. You want to know without a doubt that you'll be as hard and as hot and as enduring as you ever dreamed. And you want it now. Now means instant erection when you need it.
By contrast, psychogenic impotence typically is abrupt in onset, often in relation to psychological trauma, and may wax and wane. Patients with psychogenic impotence may have total erectile failure with one partner but not another, or be impotent during sexual intercourse but not during self-stimulation. Normally occurring spontaneous erections in the morning suggest psychogenic rather than organic causes for impotence.
Lifestyle choices that impair blood circulation can contribute to ED. Smoking, excessive drinking, and drug abuse may damage the blood vessels and reduce blood flow to the penis. Smoking makes men with atherosclerosis particularly vulnerable to ED. Being overweight and getting too little exercise also contribute to ED. Studies indicate that men who exercise regularly have a lower risk of ED.