Abrupt decrease in serum testosterone levels after an oral glucose load in men: implications for screening for hypogonadism

Caronia, Lisa M.; Dwyer, Andrew A.; Hayden, Douglas; Amati, Francesca; Pitteloud, Nelly; Hayes, Frances J.

doi:10.1111/j.1365-2265.2012.04486.x

Cited by 103 publications

(90 citation statements)

References 37 publications

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“…It has been demonstrated that glucose administration impacts TT levels in men without preexisting androgen deficiency with implications for the biochemical categorization of androgen status. A standard 75-g OGTT resulted in a 25% reduction in serum TT levels across a range of BMIs and glucose tolerance with 15% of men recording a TT level of <9.7 nmol l −1 on at least one occasion during the 120-min sampling period,64 confirming earlier observations 65. SHBG and LH levels (measured at 5 time points) were unchanged, however, a deconvolution analysis study of 50 men with age range of 18–80 years and BMI range of 20–40 kg m −2 with normal baseline glucose tolerance66 demonstrated a glucose-induced fall in pulsatile LH secretion, which was exacerbated by higher fasting insulin concentrations.…”

Section: The Impact Of Acute Changes In Glucose and Insulin On Testosmentioning

confidence: 99%

Sex steroids and glucose metabolism

Allan

2014

Asian J Androl

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Testosterone levels are lower in men with metabolic syndrome and type 2 diabetes mellitus (T2DM) and also predict the onset of these adverse metabolic states. Body composition (body mass index, waist circumference) is an important mediator of this relationship. Sex hormone binding globulin is also inversely associated with insulin resistance and T2DM but the data regarding estrogen are inconsistent. Clinical models of androgen deficiency including Klinefelter's syndrome and androgen deprivation therapy in the treatment of advanced prostate cancer confirm the association between androgens and glucose status. Experimental manipulation of the insulin/glucose milieu and suppression of endogenous testicular function suggests the relationship between androgens and insulin sensitivity is bidirectional. Androgen therapy in men without diabetes is not able to differentiate the effect on insulin resistance from that on fat mass, in particular visceral adiposity. Similarly, several small clinical studies have examined the efficacy of exogenous testosterone in men with T2DM, however, the role of androgens, independent of body composition, in modifying insulin resistance is uncertain.

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Section: The Impact Of Acute Changes In Glucose and Insulin On Testosmentioning

confidence: 99%

Sex steroids and glucose metabolism

Allan

2014

Asian J Androl

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“…There is also evidence that testosterone regulates insulin sensitivity directly and acutely (Yialamas et al 2007). 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.…”

Section: End Organ Deficits Of Androgen Deficiencymentioning

confidence: 99%

Testosterone and glucose metabolism in men: current concepts and controversies

Grossmann¹

2013

Journal of Endocrinology

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A wealth of observational studies show that low testosterone is associated with insulin resistance and with an increased risk of diabetes and the metabolic syndrome. Experimental studies have identified potential mechanisms by which low testosterone may lead to insulin resistance. Visceral adipose tissue is an important intermediate in this relationship. Actions of testosterone or its metabolite oestradiol on other tissues such as muscle, liver, bone or the brain, and body composition-independent effects may also play a role. However, definitive evidence from randomised controlled trials (RCTs) to clarify whether the association of low testosterone with disordered glucose metabolism is causative is currently lacking. It therefore remains possible that this association is due to reverse causation, or simply originates by association with common health and lifestyle factors. RCTs of testosterone therapy in men with or without diabetes consistently show modest metabolically favourable changes in body composition. Despite this, testosterone effects on glucose metabolism have been inconsistent. Recent evidence suggests that the hypothalamic-pituitary-testicular axis suppression in the majority of obese men with metabolic disorders is functional, and may be, at least in part, reversible with weight loss. Until further evidence is available, lifestyle measures with emphasis on weight reduction, treatment of comorbidities and optimisation of diabetic control should remain the first-line treatment in these men. Such measures, if successful, may be sufficient to normalise testosterone levels in men with metabolic disorders, who typically have only modest reductions in circulating testosterone levels.

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“…Although the exact mechanism by which this reduction occurs remains unclear, none of the previous studies observed any significant change in SHBG concentrations either following a glucose load [10, 11] or administration of meals [5, 8, 9], suggesting that the fall in serum testosterone is real and not simply a reflection of reduction in serum SHBG levels. What remains unclear is whether this decline in testosterone is due to a central process or secondary to reduced testicular secretion as some previous studies reported an increase in LH levels while others showed no change [6, 8, 10]. In the current study, we did not observe any significant change in serum LH levels following either a glucose load or mixed meal despite measuring serum LH levels at multiple time points in both cohorts.…”

Section: Discussionmentioning

confidence: 99%