Hypogonadism, aka testosterone deficiency or low-T, is primarily diagnosed by low total testosterone levels. However, more and more research is showing that free testosterone, which is the active fraction of total circulating testosterone, is independently associated with important health outcomes.
Levels of free testosterone decline more steeply than total testosterone as menage.[1-7 In many cases, total testosterone levels can be relatively high, but free testosterone low. Therefore it is important to assess both total and free testosterone levels in order to get a clear picture of the androgen status.
A recent study specifically assessed if baseline testosterone (total and free) levels predict muscle loss in middle-aged and elderly Japanese men over a 10 year period.
Low levels of testosterone in men may contribute the development of insulin resistance and diabetes.[1-4] However, few studies have examined the association between testosterone levels and diabetes in men in the general population.
An interesting study was cunducted to test the hypothesis that low normal levels of total, free, and bio-available testosterone are associated with prevalent diabetes in men.