More than a third of men with type 2 diabetes tested for hypogonadism in general practice have at least borderline testosterone deficiency, with levels of the hormone particularly low among men with higher BMIs, a new UK study reports.
The researchers claimed their findings showed there was ‘manifestly a subset of men with type 2 diabetes and androgen deficiency' and suggested GPs should test for hypogonadism in all men with low libido or low energy.
Testosterone testing is not currently part of standard monitoring in men with diabetes, although studies have suggested low levels are more prevalent in type 2 diabetes than in the general population.
NICE guidance on type 2 diabetes recommends that all men with diabetes should be asked about erectile dysfunction, and British Society for Sexual Medicine guidelines say that hypogonadism is a treatable cause of erectile dysfunction, which can make men less responsive to phosphodiesterase type 5 inhibitors. It recommends that all men with erectile dysfunction have serum testosterone measured.
Researchers looked at data from 6,457 men aged between 18 and 80 with either type 1 or type 2 diabetes. All attended GP practices in Cheshire between January 2008 and June 2009, and 353 men with type 2 diabetes had their serum testosterone levels measured.
Some 4.4% had severe testosterone deficiency - a serum total testosterone of less than 8.0 nmol/l – while 32.1% had borderline testosterone deficiency (8–11.99 nmol/l).
A regression analysis also showed circulating testosterone levels were independently associated with higher BMI, itself a marker of insulin resistance. There was a 1% drop in testosterone for each unit increment in BMI among patients with type 2 diabetes.
Study leader Dr Adrian Heald, a consultant in endocrinology and diabetes in Leighton Hospital, Crewe, said: ‘Our findings justify checking of serum testosterone in all men with diabetes presenting with erectile dysfunction, low libido or low energy.
‘There is manifestly a subset of men with type 2 diabetes and androgen deficiency who may benefit from testosterone replacement.'
Dr Douglas Savage, a GPSI in sexual medicine and andrology in Doncaster, said: ‘This study points out that very few [men with diabetes] are being measured, which is tragic. It also highlights that there are an enormous number with testosterone under 12,' which is said was a much more suitable cut-off than 8nmol/l.
Dr Martin Hadley-Brown, a GP with an interest in diabetes in Thetford and Chair of the Primary Care Diabetes Society this was a ‘hot topic' about diabetes clinicians. ‘There's some passionate advocates of androgen measurement and even testosterone replacement – and other doubters. This relatively small cohort does indeed seem to show some reduction in androgen levels in the diabetes cohort, but there is a big leap to say that androgen replacement would be of benefit.'
Dr Geoff Hackett, a consultant in urology in Sutton Coldfield, said that this topic is ‘vitally important', but he felt that the major weakness of this study was that it did not discuss the reason why these men had their testosterone measured. If it was because they had ED he would have expected the prevalence of severe testosterone deficiency to be higher
Primary Care Diabetes, 2011