Testosterone, SHBG and risk of type 2 diabetes in the second evaluation of the Pizarra cohort study

Abstract

Low levels of testosterone and SHBG increase the risk of T2D in men, and high levels of testosterone increase the risk of insulin resistance in women. The association between TT levels and the risk of T2D is not completely independent of other variables, such as exposure time, adiposity, insulin resistance or SHBG levels. This study also shows that the different responses between men and women are probably because of the protective effect of SHBG, levels of which are higher in women than in men.

Endogenous Sex Hormones, Metabolic Syndrome, and Diabetes in Men and Women

“…Five studies found an association between lower total T and incident diabetes [49, 55, 47, 58, 57], while 3 studies reported no association [46, 59, 48]. Two studies found an association between lower bioavailable or free T and incident diabetes [49, 57], while 3 studies reported no association [51, 46, 59]. One study examined total E2 and found an association [48], while another examined total and bioavailable E2 in men and diabetes and found no association [55].…”

“…One study examined total E2 and found an association [48], while another examined total and bioavailable E2 in men and diabetes and found no association [55]. Five studies examining SHBG found an association between lower SHBG and incident diabetes [49, 51, 46, 58, 57]; 4 did not [53, 56, 59, 48], particularly after adjustment for waist measures. Tibblin et al [57] examined IGT as well as diabetes as an outcome and also reported that lower total T was associated with incident IGT.…”

“…Two studies found an association between higher bioavailable E2 and incident diabetes [45, 50], while one study reported no association [55]. Four studies examining SHBG found an association between lower SHBG and incident diabetes [45, 50, 52, 53], and 2 did not [56, 59], particularly after adjustment for waist measurements.…”

Novel insights in SHBG regulation and clinical implications

“…The plasma samples used in this study were from 315 men from the cohort of the Pizarra Study in which 1134 people (443 men and 691 women) selected randomly from the municipal census of Pizarra (a southern Spanish population) were included. After 6 years, 928 (341 men and 587 women) were evaluated again [62]. SHBG serum levels were significantly higher in subjects using olive oil for cooking compared with subjects using sunflower oil.…”

Study of Serum Testosterone in Diabetes Mellitus

“…6,7,8 Further, reduced total testosterone (TT) levels have been associated with insulin resistance and subsequent risk for developing T2DM. 9,10 Total testosterone includes both unbound and proteinbound testosterone and is measured by radioimmunoassays or immunometric assays. A single random sample provides a good approximation of the average testosterone concentration with the realization that testosterone levels fluctuate in response to pulsatile LH.…”