High testosterone levels increase the risk of type 2 diabetes in women – but reduce the risk in men, a study shows.
Both men and women produce the ‘male’ sex hormone in various quantities, and scientists have now discovered it may play a part in disease risk.
A study of more than 425,000 people from the UK looked at more than 2,500 genetic variations linked to levels of testosterone and a protein linked to it.
The results showed that women with genetically higher testosterone have an increased risk of developing type 2 diabetes by 37 per cent.
They also had a 51 per cent higher risk of polycystic ovary syndrome (PCOS), a ‘surprising’ finding considering high testosterone was thought to be a consequence of the condition.
Higher testosterone levels reduced type 2 diabetes risk by 14 per cent in men, but increased the risk of prostate cancer.
Scientists urged more research into the effects of supplementation with testosterone based on their findings.
Higher testosterone level increases the risk of type 2 diabetes in women – but reduce the risk in men, a study shows (stock, women checks blood glucose levels)
Having too much naturally-occurring testosterone is a rare problem among men, and has been linked to liver disease, heart attack and low sperm count.
Women also produce testosterone in smaller amounts than men. Those with more testosterone than average may experience breast reductions or a deeper voice.
The study by University of Cambridge is the largest to date on the genetic regulation of sex hormone levels.
Scientists used genome-wide association studies in more than 425,000 UK Biobank participants.
They identified 2,571 genetic variations linked with differences in the levels of testosterone and its binding protein.
They found women with higher testosterone had a 51 per cent higher risk of PCOS, a condition characterised by excessive hair growth, weight gain and fertility problems.
Co-author Dr John Perry said this finding was ‘important’, because high testosterone is typically seen as a result of PCOS, not a cause.
The NHS says excess androgen – ‘male’ hormones in the body – cause physical signs such as excess facial or body hair as part of the condition.
Dr Perry said: ‘We were surprised to see that testosterone appeared to increase the risk of women developing polycystic ovary syndrome.
‘The prevailing thought has been that increased testosterone was solely the consequence of the disease, but our research suggests that testosterone may additionally play a direct role in disease susceptibility.’
The risk of type 2 diabetes soared by 37 per cent in women with higher testosterone. The metabolic condition is also known as a complication of PCOS.
In men, higher testosterone generally had a protective effect and reduced the risk of type 2 diabetes by nearly 15 per cent.
Higher testosterone increased the odds of breast and endometrial cancers in women and prostate cancer in men.
WHAT IS TESTOSTERONE?
Testosterone is the male sex hormone and is mostly made in the testicles, but also in adrenal glands, which are near the kidneys.
It causes the voice to deepen, body hair to grow and the genitals to become larger during puberty.
As well as affecting sex drive and sperm production, it also plays a role in developing strong bones and muscles, and how the body distributes fat.
Women also create small amounts of the hormone in the ovaries and adrenal glands, and it affects their fertility and bones and muscles.
Testosterone levels which are too high or too low can cause various problems.
Low testosterone in men can cause erection problems, low sex drive, infertility, weakened muscles and bones, body fat gain and hair loss.
Too much testosterone, however, can trigger puberty in boys under the age of nine, is linked to aggression, and can increase the risk of prostate problems, including cancer.
Male testosterone levels tend to be highest when he is around 20 years old, and decline naturally with age.
A connection between prostate cancer and testosterone has been evident for a while, as experts believe testosterone therapy may be a danger.
Testosterone replacement therapy (TRT) is prescribed to men with abnormally low testosterone, but health officials have warned of potential side effects such as higher risk of prostate cancer, heart disease and stroke.
Dr Perry said: ‘Testosterone-reducing therapies are widely used to treat prostate cancer, but until now it was uncertain whether lower testosterone levels are also protective against developing prostate cancer.’
The researcher said the full impact of TRT of health is still unclear, and it’s premature to advise healthy men to use it.
Dr Perry said: ‘There is clearly a trade-off when considering treatment in men – a reduction in metabolic health risk but increased susceptibility to prostate cancer.
‘In general much more information is needed on the impacts of other diseases, particularly heart disease, to inform more widespread use of supplementation in otherwise healthy people.’
Dr Perry added: ‘We don’t recommend anyone to take medication to alter testosterone levels on the basis of our findings.
‘In women, testosterone appears to be harmful for risks of metabolic diseases and some cancers.’
Dr Katherine Ruth, of Exeter University, added: ‘Our findings provide unique insights into the disease impacts of testosterone.
‘Caution is needed in using our results to justify use of testosterone supplements, until we can do similar studies of testosterone with other diseases, especially cardiovascular disease.’
The authors, writing in the journal Nature Medicine, did not offer explanations of how testosterone levels affect disease risk.
They said their findings emphasise the importance of separating men and women when looking at how testosterone affects disease risk.