Inflammation, TNF-alpha and IL-1B, reduces testosterone production. Metabolic Syndrome, an inflammatory disease, shown to be associated low Testosterone.
diets with high high-fructose corn syrup and low omega-3 shown to slow cognitive processing in rat model. This is basically, metabolic syndrome of the brain, as it is the result of hyperinsulinemia.
Around 50% of ageing, obese men presenting to the diabetes clinic have lowered testosterone levels relative to reference ranges
based on healthy young men
The absence of high-level evidence in this
area is illustrated by the Endocrine Society testosterone therapy in men with androgen deficiency clinical practice guidelines
(Bhasin et al. 2010), which are appropriate for, but not specific to men with metabolic disorders. All 32 recommendations made in these guidelines
are based on either very low or low quality evidence.
A key concept relates to making a distinction between replacement and pharmacological testosterone therapy
The presence of symptoms was more closely linked to increasing age than to testosterone levels
Findings similar to type 2 diabetes were reported for men with the metabolic syndrome, which were associated with reductions
in total testosterone of −2.2 nmol/l (95% CI −2.41 to 1.94) and in free testosterone
low testosterone is more predictive of the metabolic syndrome in lean men
Cross-sectional studies uniformly show that 30–50% of men with
type 2 diabetes have lowered circulating testosterone levels, relative to references based on healthy young men
In a recent cross-sectional study of 240 middle-aged men (mean age 54 years) with either type 2 diabetes, type 1 diabetes
or without diabetes (Ng Tang Fui et al. 2013b), increasing BMI and age were dominant drivers of low total and free testosterone respectively.
both diabetes and the metabolic syndrome are associated with a modest reduction in testosterone, in magnitude comparable
with the effect of 10 years of ageing
In a cross-sectional study of 490 men with type 2 diabetes, there was a strong independent association of low testosterone
with anaemia
In men, low testosterone is a marker of poor health, and may improve our ability to predict risk
probably the most important point made in this article
low testosterone identifies men with an adverse metabolic phenotype
Diabetic men with low testosterone are significantly more likely to be obese or insulin resistant
increased inflammation, evidenced by higher CRP levels
Bioavailable
but not free testosterone was independently predictive of mortality
It remains possible that low testosterone is a consequence of insulin resistance, or simply a biomarker,
co-existing because of in-common risk factors.
In prospective studies, reviewed in detail elsewhere (Grossmann et al. 2010) the inverse association of low testosterone with metabolic syndrome or diabetes is less consistent for free testosterone
compared with total testosterone
In a study from the Framingham cohort, SHBG but not testosterone was prospectively and independently associated with incident
metabolic syndrome
low SHBG (Ding et al. 2009) but not testosterone (Haring et al. 2013) with an increased risk of future diabetes
In cross-sectional studies of men with (Grossmann et al. 2008) and without (Bonnet et al. 2013) diabetes, SHBG but not testosterone was inversely associated with worse glycaemic control
SHBG may have biological actions
beyond serving as a carrier protein for and regulator of circulating sex steroids
In men with diabetes, free testosterone, if measured by gold standard equilibrium dialysis (Dhindsa et al. 2004), is reduced
expensive, laborious process filled with variables
Low free testosterone remains inversely associated with insulin resistance, independent of SHBG (Grossmann et al. 2008). This suggests that the low testosterone–dysglycaemia association is not solely a consequence of low SHBG.
Experimental evidence reviewed below suggests that visceral adipose tissue is an important intermediate (rather than a
confounder) in the inverse association of testosterone with insulin resistance and metabolic disorders.
testosterone promotes the commitment of
pluripotent stem cells into the myogenic lineage and inhibits their differentiation into adipocytes
testosterone regulates the metabolic functions
of mature adipocytes (Xu et al. 1991, Marin et al. 1995) and myocytes (Pitteloud et al. 2005) in ways that reduce insulin resistance.
Pre-clinical evidence (reviewed in Rao et al. (2013)) suggests that at the cellular level, testosterone may improve glucose metabolism by modulating the expression of the glucose-transported
Glut4 and the insulin receptor, as well as by regulating key enzymes involved in glycolysis.
More recently testosterone has
been shown to protect murine pancreatic β cells against glucotoxicity-induced apoptosis
Interestingly, a reciprocal feedback also appears to exist, given that not only chronic (Cameron et al. 1990, Allan 2013) but also, as shown more recently (Iranmanesh et al. 2012, Caronia et al. 2013), acute hyperglycaemia can lower testosterone levels.
There is
also evidence that testosterone regulates insulin sensitivity directly and acutely
In men with prostate cancer commencing androgen deprivation therapy, both total as well as, although not in all studies (Smith 2004), visceral fat mass increases (Hamilton et al. 2011) within 3 months
More prolonged (>12 months) androgen deprivation therapy has been associated with increased risk of diabetes in several
large observational registry studies
Testosterone has also been shown to reduce the concentration of pro-inflammatory cytokines in some, but not all studies, reviewed
recently in Kelly & Jones (2013). It is not know whether this effect is independent of testosterone-induced changes in body composition.
the observations discussed in this section suggest that it is the decrease in testosterone that causes insulin
resistance and diabetes. One important caveat remains: the strongest evidence that low testosterone is the cause rather than
consequence of insulin resistance comes from men with prostate cancer (Grossmann & Zajac 2011a) or biochemical castration, and from mice lacking the androgen receptor.
Several large prospective studies have shown that weight gain or development of type 2 diabetes is major drivers of the
age-related decline in testosterone levels
there is increasing evidence that healthy ageing by itself is generally not associated with marked reductions in
testosterone
Circulating testosterone, on an average 30%, is lower in obese compared with lean men
increased visceral fat is an important component in the association of low testosterone and insulin resistance
The vast majority of men with metabolic disorders have functional gonadal axis suppression with modest reductions in testosterone
levels
obesity is a dominant
risk factor
men with Klinefelter syndrome have an increased risk of metabolic disorders. Interestingly, greater body fat
mass is already present before puberty
Only 5% of men with type 2 diabetes have elevated LH levels
inhibition of the gonadal axis predominantly takes place in the hypothalamus,
especially with more severe obesity
Metabolic factors, such as leptin, insulin (via deficiency or resistance) and ghrelin
are believed to act at the ventromedial and arcuate nuclei of the hypothalamus to inhibit gonadotropin-releasing hormone (GNRH)
secretion from GNRH neurons situated in the preoptic area
kisspeptin has emerged as one of the
most potent secretagogues of GNRH release
hypothesis that obesity-mediated inhibition of kisspeptin signalling contributes to the suppression
of the HPT axis, infusion of a bioactive kisspeptin fragment has been recently shown to robustly increase LH pulsatility,
LH levels and circulating testosterone in hypotestosteronaemic men with type 2 diabetes
A smaller study with a similar experimental design found that acute testosterone withdrawal reduced insulin sensitivity
independent of body weight, whereas oestradiol withdrawal had no effects
suppression of the diabesity-associated HPT axis is functional, and may hence be
reversible
Obesity and dysglycaemia and associated comorbidities such as obstructive sleep apnoea (Hoyos et al. 2012b) are important contributors to the suppression of the HPT axis
weight gain and development
of diabetes accelerate the age-related decline in testosterone
Modifiable risk factors such as obesity and co-morbidities are more strongly associated with a decline in circulating testosterone
levels than age alone
55% of symptomatic androgen deficiency reverted to a normal testosterone or an asymptomatic state after 8-year follow-up,
suggesting that androgen deficiency is not a stable state
Weight loss can reactivate the hypothalamic–pituitary–testicular axis
Leptin treatment resolves hypogonadism in leptin-deficient men
The hypothalamic–pituitary–testicular axis remains responsive to treatment with aromatase inhibitors or selective oestrogen
receptor modulators in obese men
Kisspeptin treatment increases LH secretion, pulse frequency and circulating testosterone levels in hypotestosteronaemic men
with type 2 diabetes
change in BMI was associated with the change in testosterone (Corona et al. 2013a,b).
weight loss can lead to genuine reactivation
of the gonadal axis by reversal of obesity-associated hypothalamic suppression
There is pre-clinical and observational evidence that chronic hyperglycaemia can inhibit the HPT axis
in men who improved their glycaemic control over time, testosterone levels increased. By
contrast, in those men in whom glycaemic control worsened, testosterone decreased
testosterone levels should be measured after successful weight loss to identify men with an insufficient rise
in their testosterone levels. Such men may have HPT axis pathology unrelated to their obesity, which will require appropriate
evaluation and management.
Levels of total and bioavailable testosterone and SHBG were reported to be inversely correlated with the prevalence of the metabolic syndrome in men aged 40–80 years
as were total testosterone and SHBG in men aged 65–96 years
and in a cross-sectional analysis of a large cohort of non-diabetic men aged 70–89 years
In longitudinal studies, decreased levels of total testosterone and SHBG predicted an increased incidence of metabolic syndrome in nonobese men
Free testosterone level is not associated with the prevalence of metabolic syndrome in middle-aged and older men
Levels of free, bioavailable and total testosterone are lower in men with T2DM than in age-matched controls,34, 35 and decreased total testosterone level predicts incident T2DM in middle-aged men.
men with T2DM commonly have low total or free testosterone levels
Total, bioavailable and free testosterone levels are inversely correlated with fasting insulin level and insulin resistance in middle-aged men without T2DM
total testosterone is positively correlated with insulin sensitivity in men with normal or impaired glucose tolerance or T2DM
low SHBG level is more strongly associated with metabolic syndrome than low total testosterone in aging men
the recognized association between low SHBG level and insulin resistance
Low levels of SHBG are also associated with smaller, denser LDL-cholesterol molecules in nondiabetic men,58 and were found to predict increased cardiovascular disease mortality in one study of older men
Low levels of SHBG might reflect obesity, insulin resistance and overall poor health
Compared with those who have normal testosterone levels, men aged 40 years or more with total testosterone levels <9.8 nmol/l or elevated LH level have greater CIMT
In men aged 73–94 years, total testosterone was inversely correlated with CIMT
a prospective analysis of men aged 73–91 years, progression of CIMT was not related to total testosterone level, but it was inversely related to free testosterone level
A study of men aged 55 years or more found that those with total and bioavailable testosterone levels in the highest tertile had a lower risk of severe aortic atherosclerosis (detected by radiography as abdominal aortic calcification) than those with the lowest testosterone levels.
a large study of men aged 69–80 years, those with total or free testosterone in the lowest quartile had increased odds of lower-extremity peripheral arterial disease
the possibility of reverse causation has to be considered, as systemic illness can result in decreased testosterone levels
previous case–control studies and longitudinal studies have failed to identify low testosterone levels as strong predictors of clinically significant coronary disease
Reviews of trials on testosterone therapy in men with either low or low-to-normal testosterone levels have not shown consistent beneficial effects either on lipid profiles or on actual cardiovascular events.24, 54, 55 These trials, however, have not been designed or powered to detect treatment-related differences in cardiovascular outcome
Declining Testosterone or low Testosterone is clearly associated with poor health in men.
Very nice review of the association between low Testosterone and metabolic dysfunction. Low T is associated with increased metabolic syndrome, Diabetes, weight gain, insulin resistance...
Abstract ahead of print. Low Testosterone in men is associated with increased risk of metabolic syndrome and type II Diabetes. Just the opposite is the case in women: elevated Testosterone in women is associated with increasing metabolic syndrome and diabetes risk. Low SHBG is associated with increased risk in both.
Androgen deprivation therapy leads to insulin resistance, metabolic syndrome, and type II diabetes in men. Testosterone therapy in men with IR, obesity, metabolic syndrome, and type II Diabetes will result in improved cardiovascular risk.
Low Serum Testosterone inversely associated metabolic syndrome in men. This study was conducted in the Ikaria islands. No association was found with women and Testosterone. In men, Testosterone was inversely associated with waist circumference, hs-CRP, insulin, and HDL.
Abstract presented finds that Testosterone IM undecanoate significantly reduced metabolic syndrome parameters in men. This study looked at men with secondary hypogonadism and late onset. The ages were from 15-72. The full is not available as of this post. The study only looked at serum T. This limits the usefulness of this test. According to this abstract, no evaluation of SHBG was performed. Though not significant, PSA and prostate volume increased.
low vitamin D associated with an increased odds ratio of elevated blood pressure and elevated triglycerides in post-menopausal women with metabolic syndrome.
When you look at PCOS in women, it is really just the early manifestation of Metabolic Syndrome. PCOS no longer needs to be viewed through the prism of hormones and/or infertility but the means through which disease will walk.
Our findings should generate significant doubt about the presumed health of collegiate football linemen. That is a startling conclusion. This conclusion comes from the fact that 49% of Lineman evaluated in this study were found to have Metabolic Syndrome.