Impotence, also known as erectile dysfunction or ED, is a condition in which a man is unable to get or hold an erection long enough to have a satisfactory sex life. Impotence is a common problem, affecting up to half of Australian men between the ages of 40 and 70 years. The risk of developing erectile dysfunction increases as you get older.In the past, doctors considered impotence to be a mainly psychological problem, caused by performance anxiety or stress. Now, doctors know that many cases of impotence have a physical cause, which usually can be treated. Often, a combination of physical and psychological factors contributes to erectile dysfunction.Physical causes of impotencePhysical causes of impotence can include:problems with blood to flow into and out of the penis;damage to the nerves that send signals from the body’s central nervous system to the penis; and, more rarely,a deficiency in testosterone or other hormones.Some medicines can contribute to impotence, as can some types of surgery and radiotherapy treatments.Blocked blood vessels to the penisA very common cause of impotence is when blood flow into the penis is reduced. This can be due to atherosclerosis, also known as hardening of the arteries. In atherosclerosis, the arteries are clogged and narrowed, resulting in reduced blood flow.Risk factors for atherosclerosis include:high cholesterol;high blood pressure;obesity;sleep apnoea;diabetes; andsmoking.If your erection problems are caused by atherosclerosis, there is a chance that the arteries in other parts of your body (e.g. the coronary arteries that supply your heart) are also affected by atherosclerosis. In fact, erection problems may be the first sign that you are at risk of coronary heart disease.Because the arteries to the penis are narrower than those to the heart, you may develop symptoms of erectile dysfunction before you experience any symptoms of heart disease, such as angina. So seeing your doctor about erection problems may be important for your overall physical health.Impotence can also be caused by a blood clot that prevents enough blood from flowing into the penis to cause an erection.Venous leakageIn some men, blood can flow in to the penis easily, but the problem is that it leaks out again, so an erection cannot be sustained. This is called venous leakage. Doctors aren’t certain of the cause of venous leakage, but they can perform surgery to help repair it.Medicines that can cause impotenceMany medicines can cause erection problems as a side effect, including:diuretics (sometimes known as ‘water tablets’ - often used for high blood pressure);high blood pressure medications;cholesterol-lowering medicines (including statins);some types of antipsychotics;antidepressants;cancer treatments;some medicines used to treat heartburn and stomach ulcers;antihistamines;some pain medicines; andcertain epilepsy medications.If you experience impotence after starting a new medication, tell your doctor, who may be able to prescribe a different medicine for you. Don’t stop taking a medicine without first consulting your doctor. You should also tell your doctor about any over-the-counter medicines or complementary remedies you may be taking.The following table contains a list of specific medicines that may cause or contribute to erectile dysfunction. This list may not cover all types of medicines that can cause erectile dysfunction, so always ask your doctor if you are in doubt. Also, for some of these medicines ED is a very rare side effect. Most men taking these medicines do not experience erectile dysfunction.Medicines that may cause erectile dysfunctionType of medicineExamplesACE inhibitorscaptopril (Capoten), enalapril (Renitec), perindopril (Perindo), ramipril (Tritace), and othersAntidepressantsamitriptyline (Endep), clomipramine (Anafranil), desvenlafaxine (Pristiq), fluoxetine (Prozac), paroxetine (Aropax), sertraline (Zoloft), venlafaxine (Altven, Efexor), and othersAnti-epilepticsclonazepam (Rivotril), pregabalin (Lyrica)Antifungalsitraconazole (Sporanox)Anti-ulcer drugscimetidine (Magicul), nizatidine (Tazac), ranitidine (Zantac), and othersBeta-blockerspropranolol (Inderal), metoprolol (Betaloc, Lopresor), and othersOther blood pressure-lowering medicinesclonidine (Catapres), lercanidipine/enalapril (Zan-Extra), losartan (Cozaar), perindopril/amlodipine (Coveram), olmesartan/amlodipine (Sevikar), telmisartan/amlodipine (Twynsta), valsartan/hydrochlorothiazide (Co-Diovan)Calcium-channel blockersdiltiazem (Cardizem), felodipine (Plendil), nifedipine (Adalat)Cholesterol-lowering drugsatorvastatin (Lipitor), ezetimibe/simvastatin (Vytorin), fluvastatin (Lescol, Vastin), gemfibrozil (Ausgem), pravastatin (Pravachol), simvastatin (APO-simvastatin, Lipex, Zocor), and othersDiuretics ('water tablets')bumetanide (Burinex), chlorthalidone (Hygroton), spironolactone (Aldactone), and othersSchizophrenia drugsamisulpride (Solian, Sulprix), haloperidol (Haldol, Serenace), olanzapine (Lanzek, Ozin, Zypine, Zyprexa), paliperidone (Invega), risperidone (Rispa, Risperdal), ziprasidone (Zeldox)Combination cholesterol-lowering and anti-hypertensiveamlodipine/atorvastatin (Caduet, Cadatin)Pain medicinesfentanyl (Denpax, Durogesic), hydromorphone (Jurnista), morphine (Momex SR, MS Contin), oxycodone (OxyContin, OxyNorm, Targin), tramadolMiscellaneousoestrogens, antiandrogens, anticancer drugs and some chemotherapy treatments, baclofen (Clofen, Lioresal); cyproterone (Androcur, Cyprohexal, Cyprostat), degarelix (Firmagon), etoricoxib (Arcoxia), finasteride (Proscar and Propecia), flutamide (Flutamin), rotigotine (Neupro), triptorelin (Diphereline)*The names in brackets are just some examples of the trade names each specific medicine is marketed under in Australia. The medicine may also be known by other trade names.Diabetes and erectile dysfunctionMen who have diabetes have a higher risk of developing impotence than other men. Diabetes contributes to impotence because it can damage blood vessels and cause a type of nerve damage known as peripheral neuropathy.Hormones and impotenceLow levels of the male hormone, testosterone, are more commonly linked to a lowered sex drive, rather than impotence itself. Only a small percentage of cases of impotence are caused by hormone deficiency.Low testosterone levels may be the result of a condition called hypogonadism, in which the testicles don’t produce enough testosterone. More rarely, low testosterone can be caused by the pituitary (a small gland at the base of the brain) not secreting sufficient hormones to stimulate the testes to produce testosterone. The pituitary is also sometimes affected by small benign (non-cancerous) tumours that secrete prolactin, another hormone that can cause impotence.Mildly decreased levels of testosterone are often not due to specific testicular or pituitary problems, but rather stress or depression. In this situation, testosterone replacement is rarely of any benefit.Other hormone problems, including thyroid disease, can also cause impotence.Prostate cancer and erectile dysfunctionThe advanced stages of prostate cancer can affect the nerves and arteries that are vital for an erection.Radiation treatment for prostate cancer can harm the erectile tissues of the penis, and prostate cancer surgery can cause nerve or artery damage to the penis.Treatment for advanced prostate cancer often includes medicines that counteract testosterone, and commonly cause erectile dysfunction as well as loss of sexual interest.Peyronie’s diseasePeyronie’s disease is an uncommon condition that affects a man’s sex life because his penis curves abnormally and causes pain when he has an erection. He might also be unable to have a hard erection. The curvature of the penis is caused by a scar, called a plaque, that forms in the penis.Other physical causes of impotenceSeveral other factors and conditions can contribute to erectile dysfunction, including the following.Depression. Many men find that when they’re suffering from depression, they lose interest in sex and can’t get or keep an erection. Asking your doctor for treatments for depression may help alleviate your erection problems as well.Smoking contributes to vascular disease (disease of the blood vessels), so it can contribute to erectile dysfunction by affecting blood flow to the penis. Giving up smoking often has a beneficial effect on erectile function.Excessive alcohol use. Alcoholism can cause permanent nerve damage, resulting in impotence. This nerve damage is called peripheral neuropathy. Long-term alcohol use can impair the liver’s ability to function, resulting in a hormone imbalance in which a man has too much of the female sex hormone, oestrogen. On a day-to-day level, alcohol dulls the central nervous system, adversely affecting sexual response.Illicit drug use. Illicit drugs such as marijuana, cocaine, heroin, barbiturates, and amphetamines act on the central nervous system, impairing the body’s ability to respond sexually.Certain exercises. Nerve and artery damage can be caused by prolonged cycling, rodeo riding, or use of a rowing machine, resulting in the inability to get an erection. Often, minimising the use of hard bicycle seats and exercise machine seats, as well as correct positioning of the seat, will help restore sexual function.Surgery to organs near the nerve pathways of the penis, such as the bladder, rectum and prostate, can cause nerve or artery damage to the penis, resulting in the inability to have an erection.Injuries. Impotence can be caused by spinal cord injury; injury to your sex organs; or a pelvic fracture, which can cause damage to the nerves of the penis, or damage the blood vessels, resulting in reduced blood flow to the penis.Conditions affecting the nervous system. Multiple sclerosis (MS) and other degenerative diseases of the nervous system, such as Parkinson’s disease, can damage the nerves involved in erections.Psychological causes of impotenceMost cases of impotence have physical causes, but, in some men, psychological factors are the main contributors to impotence.Impotence that’s triggered by psychological factors is more common in men who are sexually inexperienced. Psychological erectile dysfunction may only occur when you’re with just one particular person. You’re also more likely to have morning erections, and be able to have an erection when you masturbate, than men whose impotence has a physical cause.Here are some psychological factors that can have an impact on your erections.Stress and anxietyWhen you’re stressed and focusing on other issues apart from sex, you might find that you don’t want to have sex as often and there might be a drop in your ability to perform when you do try. You might find that tackling the source of your stress can have benefits in the bedroom as well.Fear of failureAnxiety about your sexual prowess (commonly called performance anxiety) can, in itself, contribute to failure. By putting pressure on yourself, you become too anxious to get an adequate erection.Most men experience isolated episodes of erectile failure. Even when the transient physical cause has passed, anxiety that it may recur is sufficient to prevent erection. Anxiety, whether about something specifically sexual or part of a wider anxiety syndrome, is never helpful to good sexual function.Problems with your relationship and impotenceImpotence may be a manifestation of a poor relationship, or a problematic time in a relationship. Sexual boredom, tension or anger among partners, and lack of intimacy and communication are all possible triggers of erectile dysfunction. In these cases, seeing a counsellor may help.It’s worth remembering that impotence is a complex medical condition, which may have more than one cause. For example, if impotence is the result of a side effect of medicine or an underlying disease, the anxiety caused by lack of performance may perpetuate the erectile dysfunction even after the physical cause has been dealt with.Almost any chronic (ongoing) physical or mental health disorder, including those with no direct effect on penile nerves or blood supply, can have a powerful effect on sexuality, sexual self-image and erectile function.If you’re worried about your sexual response or the quality of your erections, don’t be afraid to talk to your doctor, who has access to treatments that can help. Last Reviewed: 16 December 2016
Failure to achieve an erection is not uncommon for most men and may be considered normal even if it happens as often as 20 percent of the time. There is a wide range of normal when it comes to sexual functioning and sexual relationships. "Generally if a couple feels comfortable with their sex life and they enjoy intimacy together, erectile dysfunction may not be much of an issue. But if erectile dysfunction is causing stress in a relationship, then help is available," says Feloney.
Dr. Wyne, in Houston, said, "When I hear a catchy little phrase, or someone is trying to get us to use a drug that is not based on clinical data, the cynical part of me asks where did it come from." She added, "There is a very important role for testosterone replacement therapy. It's wonderful that we have all these options, but we need to be using them appropriately, in a safe and efficacious manner."
After bombarding consumers with advertising, and massaging physicians with free meals and medical "information," the stage is set to seal the deal. "The fat guy has been seeing the ads on TV," said Fugh-Berman. "The doc has just come from a medical meeting where they were talking about how using testosterone can fight depression, etc., and they are being primed in a different way."
Testosterone is only one of many factors that influence aggression and the effects of previous experience and environmental stimuli have been found to correlate more strongly. A few studies indicate that the testosterone derivative estradiol (one form of estrogen) might play an important role in male aggression.[66][67][68][69] Studies have also found that testosterone facilitates aggression by modulating vasopressin receptors in the hypothalamus.[70]
Some of these signs and symptoms can be caused by various underlying factors, including medication side effects, obstructive sleep apnea, thyroid problems, diabetes and depression. It's also possible that these conditions may be the cause of low testosterone levels, and treatment of these problems may cause testosterone levels to rise. A blood test is the only way to diagnose a low testosterone level.
A large number of side-effects have been attributed to testosterone. In our clinical experience, the incidence of significant adverse effects with treatment producing physiological testosterone levels is low, and many side effects attributed to testosterone are mainly relevant to supraphysiological replacement. Some adverse effects are specific to a given mode of delivery and have already been described. Potential adverse effects concerning the prostate have also been discussed and require appropriate monitoring of symptoms, PSA and digital rectal examination. Other tumors which may be androgen responsive include cancer of the breast and primary liver tumors, and these are both contraindications to testosterone treatment
While testosterone stimulates a man’s sex drive, it also aids in achieving and maintaining an erection. Testosterone alone doesn’t cause an erection, but it stimulates receptors in the brain to produce nitric oxide. Nitric oxide is a molecule that helps trigger a series of chemical reactions necessary for an erection to occur. When testosterone levels are too low, a man may have difficulty achieving an erection prior to sex or having spontaneous erections (for example, during sleep).
The normal development of the prostate gland is dependent on the action of testosterone via the androgen receptor, and abnormal biosynthesis of the hormone or inactivating mutations of the androgen receptor are associated with a rudimentary prostate gland. Testosterone also requires conversion to dihydrotestosterone in the prostate gland for full activity. In view of this link between testosterone and prostate development, it is important to consider the impact that testosterone replacement may have on the prevalence and morbidity associated with benign prostatic hypertrophy (BPH) and prostate cancer, which are the common conditions related to pathological growth of the prostate gland.
In order to discuss the biochemical diagnosis of hypogonadism it is necessary to outline the usual carriage of testosterone in the blood. Total serum testosterone consists of free testosterone (2%–3%), testosterone bound to sex hormone binding globulin (SHBG) (45%) and testosterone bound to other proteins (mainly albumin −50%) (Dunn et al 1981). Testosterone binds only loosely to albumin and so this testosterone as well as free testosterone is available to tissues and is termed bioavailable testosterone. Testosterone bound to SHBG is tightly bound and is biologically inactive. Bioavailable and free testosterone are known to correlate better than total testosterone with clinical sequelae of androgenization such as bone mineral density and muscle strength (Khosla et al 1998; Roy et al 2002). There is diurnal variation in serum testosterone levels with peak levels seen in the morning following sleep, which can be maintained into the seventh decade (Diver et al 2003). Samples should always be taken in the morning before 11 am to allow for standardization.
"One of the reasons erectile dysfunction increases with age is that the diseases that lead to it also increase with age," notes Dr. Feloney. Evaluating the causes of erectile dysfunction starts with your doctor taking a good health history and giving you a physical exam. Common medical issues that can lead to erectile dysfunction include diabetes, high blood pressure, hardening of the arteries, low testosterone, and neurological disease. Talk to your doctor about better managing these health conditions.
The sexual hormone can encourage fair behavior. For the study, subjects took part in a behavioral experiment where the distribution of a real amount of money was decided. The rules allowed both fair and unfair offers. The negotiating partner could subsequently accept or decline the offer. The fairer the offer, the less probable a refusal by the negotiating partner. If no agreement was reached, neither party earned anything. Test subjects with an artificially enhanced testosterone level generally made better, fairer offers than those who received placebos, thus reducing the risk of a rejection of their offer to a minimum. Two later studies have empirically confirmed these results.[71][72][73] However men with high testosterone were significantly 27% less generous in an ultimatum game.[74] The Annual NY Academy of Sciences has also found anabolic steroid use which increase testosterone to be higher in teenagers, and this was associated with increased violence.[75] Studies have also found administered testosterone to increase verbal aggression and anger in some participants.[76]
Although not proven, it is likely that erectile dysfunction can be prevented by good general health, paying particular attention to body weight, exercise, and cigarette smoking. For example, heart disease and diabetes are problems that can cause erectile dysfunction, and both are preventable through lifestyle changes such as sensible eating and regular exercise. Furthermore, early diagnosis and treatment of associated conditions like diabetes, hypertension and high cholesterol may prevent or delay erectile dysfunction, or stop the erectile dysfunction from getting more serious.
Erectile dysfunction in older men. Because erections primarily involve the blood vessels, it is not surprising that the most common causes in older men are conditions that block blood flow to the penis, such as atherosclerosis or diabetes. Another vascular cause may be a faulty vein, which lets blood drain too quickly from the penis. Other physical disorders, as well as hormonal imbalances and certain operations, may also result in erectile dysfunction.
It appears that testosterone has NOS-independent pathways as well. In one study, castrated rats were implanted with testosterone pellets and then divided into a group that received an NOS inhibitor (L-nitro-L-arginine methyl ester [L-NAME]) and a control group that received no enzyme. [24] The castrated rats that were given testosterone pellets and L-NAME still had partial erections, a result suggesting the presence of a pathway independent of NOS activity.
“Although having sex at 70 is not the same as having sex at 20, erectile dysfunction is not a normal part of aging,” according to Michael Feloney, MD, urologic surgeon and expert on sexual dysfunction issues at the Nebraska Medical Center in Omaha. “You should still be able to have a satisfying sex life as you age." If you are experiencing erectile dysfunction, these 10 dos and don'ts may help.
Abnormally high levels of testosterone could be the result of an adrenal gland disorder, or even cancer of the testes. High levels may also occur in less serious conditions. Congenital adrenal hyperplasia, which can affect males and females, is a rare but natural cause for elevated testosterone production. Your doctor may order other tests if your levels are exceedingly high.
Studies conducted in rats have indicated that their degree of sexual arousal is sensitive to reductions in testosterone. When testosterone-deprived rats were given medium levels of testosterone, their sexual behaviors (copulation, partner preference, etc.) resumed, but not when given low amounts of the same hormone. Therefore, these mammals may provide a model for studying clinical populations among humans suffering from sexual arousal deficits such as hypoactive sexual desire disorder.[37]
Effective treatment for erectile dysfunction is available, and for most men will allow the return to a fulfilling sex life. The side effects of the treatment for erectile dysfunction vary depending on the treatment that is used. Some may interrupt the spontaneity of sexual activity. For example, PDE-5 inhibitors typically need to be taken one hour before sex. Side effects may include headaches, indigestion, vasodilation, diarrhoea and blue tinge to vision. Other treatments such as penile injections may cause pain at the injection site, or an erection that will not go down. Treatment options need to be carefully discussed with your doctor to determine which one is best suited to you.
Testosterone does a lot more than you’d think, whether we’re talking about male or female biology. It’s the hormone that helps you burn fat, build muscle [1], and increase your sex drive [2], and its power doesn’t stop there. Keeping your testosterone levels in a normal range can make you happier, too [3], and testosterone can even improve your cardiovascular health and decrease your risk of mortality (from all causes!), according to a study of 83,000 older men who underwent testosterone replacement therapy [4].
Low testosterone levels may contribute to decreased sex drive, erectile dysfunction, fragile bones, and other health issues. Having low testosterone levels may also indicate an underlying medical condition. See your doctor if you suspect you have low testosterone. A simple blood test is all it takes to check if your testosterone falls within the normal range.

Supplements are popular and often cheaper than prescription drugs for ED. However, supplements have not been tested to see how well they work or if they are a safe treatment for ED. Patients should know that many over-the-counter drugs have been found on drug testing to have ‘bootlegged' PDE 5 Inhibitors as their main ingredient. The amounts of Viagra, Cialis, Levitra or Stendra that may be in these supplements is not under quality control and may differ from pill to pill. The FDA has issued consumer warnings and alerts.
Best of all? It's easy. "Low T Center is set up so men can walk in, take a simple blood test, and know within 30 minutes whether or not they are a candidate for testosterone replacement therapy, or TRT. Men who qualify get their first injection on the spot, and will continue to come in three times per month to receive a quick testosterone injection."
In a prospective study from the Prostate Cancer Prevention Trial database, Thompson et al reported that men presenting with ED had a significantly higher chance of developing a cardiovascular event over a 7-year follow-up period. [55] The hazard ratio was 1.45, which is in the range of risk associated with current smoking or a family history of MI.

Erectile dysfunction can cause strain on a couple. Many times, men will avoid sexual situations due to the emotional pain associated with ED, causing their partner to feel rejected or inadequate. It is important to communicate openly with your partner. Some couples consider seeking treatment for ED together, while other men prefer to seek treatment without their partner's knowledge. A lack of communication is the primary barrier for seeking treatment and can prolong the suffering. The loss of erectile capacity can have a profound effect on a man. The good news is that ED can usually be treated safely and effectively.
The normal development of the prostate gland is dependent on the action of testosterone via the androgen receptor, and abnormal biosynthesis of the hormone or inactivating mutations of the androgen receptor are associated with a rudimentary prostate gland. Testosterone also requires conversion to dihydrotestosterone in the prostate gland for full activity. In view of this link between testosterone and prostate development, it is important to consider the impact that testosterone replacement may have on the prevalence and morbidity associated with benign prostatic hypertrophy (BPH) and prostate cancer, which are the common conditions related to pathological growth of the prostate gland.
Testosterone levels generally peak during adolescence and early adulthood. As you get older, your testosterone level gradually declines — typically about 1 percent a year after age 30 or 40. It is important to determine in older men if a low testosterone level is simply due to the decline of normal aging or if it is due to a disease (hypogonadism).
Patients receiving penile prostheses should be instructed in the operation of the prosthesis before surgery and again in the postoperative period. The prosthesis usually is not activated until approximately 6 weeks after surgery, so as to allow the edema and pain to subside. The prosthesis is checked in the office before the patient begins to use it.
These are not currently approved by the FDA for ED management, but they may be offered through research studies (clinical trials). Patients who are interested should discuss the risks and benefits (informed consent) of each, as well as costs before starting any clinical trials. Most therapies not approved by the FDA are not covered by government or private insurance benefits.
Testosterone may prove to be an effective treatment in female sexual arousal disorders,[52] and is available as a dermal patch. There is no FDA approved androgen preparation for the treatment of androgen insufficiency; however, it has been used off-label to treat low libido and sexual dysfunction in older women. Testosterone may be a treatment for postmenopausal women as long as they are effectively estrogenized.[52]
Men can experience a range of symptoms if testosterone decreases more than it should. Low testosterone, or low T, is diagnosed when levels fall below 300 nanograms per deciliter (ng/dL). A normal range is typically 300–1000 ng/dL, according to the U.S. Food and Drug Administration. A blood test called a serum testosterone test is used to determine your level of circulating testosterone.
For obvious reasons, ED can be a sensitive subject, one that until relatively recently men were more likely to try to hide than to deal with. Fortunately, a deeper understanding of the variety of causes of erectile dysfunction has led to medications, therapies, and other treatments that can be more individualized and more likely to be effective—and more open discussion about addressing the concern.
The physical side effects of chemotherapy are usually temporary and resolve within one to two weeks after stopping the chemotherapy. However, chemotherapy agents, such as Ciplatin or Vincristine, may interfere with the nerves that control erection leading to possible impotence. Make sure you discuss potential side effects of cancer chemotherapy with your doctor or healthcare provider.

The dorsal artery provides for engorgement of the glans during erection, whereas the bulbourethral artery supplies the bulb and the corpus spongiosum. The cavernous artery effects tumescence of the corpus cavernosum and thus is principally responsible for erection. The cavernous artery gives off many helicine arteries, which supply the trabecular erectile tissue and the sinusoids. These helicine arteries are contracted and tortuous in the flaccid state and become dilated and straight during erection. [9]


Trials of testosterone treatment in men with type 2 diabetes have also taken place. A recent randomized controlled crossover trial assessed the effects of intramuscular testosterone replacement to achieve levels within the physiological range, compared with placebo injections in 24 men with diabetes, hypogonadism and a mean age of 64 years (Kapoor et al 2006). Ten of these men were insulin treated. Testosterone treatment led to a significant reduction in glycated hemoglobin (HbA1C) and fasting glucose compared to placebo. Testosterone also produced a significant reduction in insulin resistance, measured by the homeostatic model assessment (HOMA), in the fourteen non-insulin treated patients. It is not possible to measure insulin resistance in patients treated with insulin but five out of ten of these patients had a reduction of insulin dose during the study. Other significant changes during testosterone treatment in this trial were reduced total cholesterol, waist circumference and waist-hip ratio. Similarly, a placebo-controlled but non-blinded trial in 24 men with visceral obesity, diabetes, hypogonadism and mean age 57 years found that three months of oral testosterone treatment led to significant reductions in HbA1C, fasting glucose, post-prandial glucose, weight, fat mass and waist-hip ratio (Boyanov et al 2003). In contrast, an uncontrolled study of 150 mg intramuscular testosterone given to 10 patients, average age 64 years, with diabetes and hypogonadism found no significant change in diabetes control, fasting glucose or insulin levels (Corrales et al 2004). Another uncontrolled study showed no beneficial effect of testosterone treatment on insulin resistance, measured by HOMA and ‘minimal model’ of area under acute insulin response curves, in 11 patients with type 2 diabetes aged between 33 and 73 years (Lee et al 2005). Body mass index was within the normal range in this population and there was no change in waist-hip ratio or weight during testosterone treatment. Baseline testosterone levels were in the low-normal range and patients received a relatively small dose of 100 mg intramuscular testosterone every three weeks. A good increase in testosterone levels during the trial is described but it is not stated at which time during the three week cycle the testosterone levels were tested, so the lack of response could reflect an insufficient overall testosterone dose in the trial period.
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