The role of sex hormone-binding globulin (SHBG), testosterone, and other sex steroids, on the development of type 2 diabetes in a cohort of community-dwelling middle-aged to elderly men

AR/RKIP pathway mediates the inhibitory effects of icariin on renal fibrosis and endothelial-to-mesenchymal transition in type 2 diabetic nephropathy

ETHNOPHARMACOLOGICAL RELEVANCE

Herba epimedium brevicornu maxim is traditionally known as a sexual enhancement, and has the effect of tonifying kidney yang. Icariin is a flavonoid extracted from epimedium brevicornu maxim, and has been shown to improve nephropathy disease.

AIM OF THE STUDY

This study investigated the possible role of icariin in regulating renal EndMT in type 2 diabetic nephropathy (T2DN).

MATERIALS AND METHODS

Male type 2 diabetic Sprague Dawley rats, Male D2.BKS(D)-Leprdb/J (db/db) mice, and mouse glomerular endothelial cells were utilized to evaluate the effect of icariin. Western blotting, Q-PCR, immunohistochemistry, H&E, Masson staining, immunofluorescence, and siRNA transfection, were performed in this study.

RESULTS

The inhibitory function of icariin in renal fibrosis and renal EndMT was verified in type 2 diabetic animals. Methyltestosterone suppressed renal fibrosis and EndMT in db/db mice. Androgen receptor (AR), the major receptor of testosterone, was upregulated by icariin. The AR antagonist MDV3100, blocked the inhibition by icariin in renal EndMT, revealing that icariin repressed renal EndMT by activating AR. In addition, icariin and methyltestosterone upregulated the Raf kinase inhibitor protein (RKIP) in db/db mice. Furthermore, siRNA-RKIP inhibited the effect of icariin on EndMT. The MEK/ERK pathway, as the downstream pathway of RKIP, was suppressed by icariin and methyltestosterone. Of note, the effect of icariin on the MEK/ERK pathway was abolished by MDV3100 or siRNA-RKIP.

CONCLUSIONS

These results supported that icariin targeted AR/RKIP/MEK/ERK pathway to suppress renal fibrosis and EndMT in T2DN.

Characteristics of elderly diabetes patients: focus on clinical manifestation, pathogenic mechanism, and the role of traditional Chinese medicine

Diabetes mellitus has become a major public health issue globally, putting an enormous burden on global health systems and people. Among all diseased groups, a considerable part of patients are elderly, while their clinical features, pathogenic processes, and medication regimens are different from patients of other ages. Despite the availability of multiple therapies and techniques, there are still numerous elderly diabetes patients suffering from poor blood glucose control, severe complications, and drug adverse effects, which negatively affect the quality of life in their golden years. Traditional Chinese Medicine (TCM) has been widely used in the treatment of diabetes for several decades, and its relevant clinical practice has confirmed that it has a satisfactory effect on alleviating clinical symptoms and mitigating the progression of complications. Chinese herbal medicine and its active components were used widely with obvious clinical advantages by multiple targets and signaling pathways. However, due to the particular features of elderly diabetes, few studies were conducted to explore Traditional Chinese Medicine intervention on elderly diabetic patients. This study reviews the research on clinical features, pathogenic processes, treatment principles, and TCM treatments, hoping to provide fresh perspectives on the prevention and management strategies for elderly diabetes.

EMAS position statement: Testosterone replacement therapy in older men

INTRODUCTION

Late-onset hypogonadism is the clinical entity characterised by low testosterone concentrations associated with clinical symptoms in the absence of organic disease in ageing men. It has been associated with metabolic syndrome, reduced bone mineral density, and increased cardiovascular morbidity and mortality risk. Although testosterone replacement therapy (TRT) reverses most of these conditions in young hypogonadal men, the risk/benefit ratio of TRT in older men is debatable.

AIM

To update the 2015 EMAS statement on TRT in older men with new research on late-onset hypogonadism and TRT.

MATERIALS AND METHODS

Literature review and consensus of expert opinion.

SUMMARY RECOMMENDATIONS

TRT should be offered only to symptomatic older men with confirmed low testosterone concentrations after explaining the uncertainties regarding the long-term safety of this treatment. TRT may be offered to men with severe hypogonadism and erectile dysfunction to improve sexual desire, erectile, and orgasmic function. It should also be considered in hypogonadal men with severe insulin resistance or pre-diabetes mellitus. TRT may also be considered, in combination with proven treatment strategies, for osteoporosis, or for selected patients with persistent mild depressive symptoms and/or low self-perceived quality of life, combined with standard medical care for each condition. TRT is contraindicated in hypogonadal men actively seeking fertility treatment. Due to a lack of data, TRT should not be routinely used in older men to improve exercise capacity/physical function, improve cognitive function, or prevent cognitive decline. TRT must be avoided in older, frail men with known breast cancer or untreated prostate cancer and all men who have had myocardial infarction or stroke within the last four months, and those with severe or decompensated heart failure. The quality of evidence regarding patients with previous prostate cancer or cardiovascular disease is too low to draw definitive conclusions. Any limits on duration of use are arbitrary, and treatment should continue for as long as the man feels the benefits outweigh the risks for him, and decisions must be made on an individual basis. Withdrawal should be considered when hypogonadism is reversed after the resolution of underlying disorder. Short-acting transdermal preparations should be preferred for TRT initiation in older men, but injectable forms may be considered subsequently. Older men on TRT should be monitored at 3, 6, and 12 months after initiation and at least yearly thereafter, or earlier and more frequently if indicated. Evaluation should include assessment of the clinical response, and measurement of total testosterone, haematocrit, and prostate-specific antigen (PSA) concentrations. Bone density and/or quality should also be assessed. Obese and overweight patients should be encouraged to undergo lifestyle modifications, including exercise and weight loss, to increase endogenous testosterone.

Advances in mitochondria-centered mechanism behind the roles of androgens and androgen receptor in the regulation of glucose and lipid metabolism

An increasing number of studies have reported that androgens and androgen receptors (AR) play important roles in the regulation of glucose and lipid metabolism. Impaired glucose and lipid metabolism and the development of obesity-related diseases have been found in either hypogonadal men or male rodents with androgen deficiency. Exogenous androgens supplementation can effectively improve these disorders, but the mechanism by which androgens regulate glucose and lipid metabolism has not been fully elucidated. Mitochondria, as powerhouses within cells, are key organelles influencing glucose and lipid metabolism. Evidence from both pre-clinical and clinical studies has reported that the regulation of glucose and lipid metabolism by androgens/AR is strongly associated with the impact on the content and function of mitochondria, but few studies have systematically reported the regulatory effect and the molecular mechanism. In this paper, we review the effect of androgens/AR on mitochondrial content, morphology, quality control system, and function, with emphases on molecular mechanisms. Additionally, we discuss the sex-dimorphic effect of androgens on mitochondria. This paper provides a theoretical basis for shedding light on the influence and mechanism of androgens on glucose and lipid metabolism and highlights the mitochondria-based explanation for the sex-dimorphic effect of androgens on glucose and lipid metabolism.

Sex Hormones and Diabetes in 45- to 74-year-old Men and Postmenopausal Women: The Hispanic Community Health Study

Previous studies demonstrated associations of endogenous sex hormones with diabetes. Less is known about their dynamic relationship with diabetes progression through different stages of the disease, independence of associations, and role of the hypothalamic-pituitary gonadal axis. The purpose of this analysis was to examine relationships of endogenous sex hormones with incident diabetes, prediabetes, and diabetes traits in 693 postmenopausal women and 1015 men aged 45 to 74 years without diabetes at baseline participating in the Hispanic Community Health Study/Study of Latinos and followed for 6 years. Baseline hormones included estradiol, luteinizing hormone (LH), follicle stimulating hormone (FSH), sex hormone-binding globulin (SHBG), dehydroepiandrosterone sulfate (DHEAS), and, in men, testosterone and bioavailable testosterone. Associations were analyzed using multivariable Poisson and linear regressions. In men, testosterone was inversely associated with conversion from prediabetes to diabetes (incidence rate ratio [IRR] for 1 SD increase in testosterone: 0.821; 95% CI, 0.676, 0.997; P = 0.046), but not conversion from normoglycemia to prediabetes. Estradiol was positively associated with increase in fasting insulin and homeostatic model assessment of insulin resistance. In women, SHBG was inversely associated with change in glycosylated hemoglobin, postload glucose, and conversion from prediabetes to diabetes (IRR = 0.62; 95% CI, 0.44, 0.86, P = 0.005) but not from normoglycemia to prediabetes. Relationships with other hormones varied across glycemic measures. Stronger associations of testosterone and SHBG with transition from prediabetes to diabetes than from normoglycemic to prediabetes suggest they are operative at later stages of diabetes development. Biologic pathways by which sex hormones affect glucose homeostasis await future studies.

Pharmacological approaches to the prevention of type 2 diabetes mellitus

About 1 in 10 adults worldwide are estimated to have diabetes mellitus. They are at risk of developing life-threatening complications resulting in reduced quality of life, increased mortality and higher healthcare costs. The ability to prevent or delay type 2 diabetes mellitus (T2DM) by modifying some of its risk factors has been hypothesized for decades. The long and often gradual time-course of increasing dysglycemia prior to diabetes diagnosis suggests that interventions during that period could be effective in preventing T2DM. In addition to lifestyle modifications, certain drugs prevent or slow development of hyperglycemia. Recently, drugs used for obesity management were shown to prevent T2DM. In this review, we discuss various pharmacotherapeutic options for preventing T2DM.

The effects of different physiologic concentrations of prolactin in association with reproductive hormones on the incidence of type 2 diabetes mellitus in men: Tehran Lipid and Glucose Study

BACKGROUND

Data is inconsistent and, for the most part, not sufficient to demonstrate the association between serum Prolactin (PRL) concentration within the physiologic range and the incidence rate of type 2 Diabetes Mellitus (DM) among men. Moreover, since both PRL and type 2 DM are associated with reproductive hormones, investigating these hormones might improve our understanding of how PRL might impose its effect on the incidence rate of type 2 DM.

METHODS

For the present study, 652 eligible men aged 29-70 with a normal baseline PRL concentration were selected from the Tehran Lipid and Glucose Study (TLGS). Participants were sub-classified into three groups (tertiles) according to the serum concentration of PRL and were followed for 15.8 years. The incidence of type 2 DM and PRL, LH, FSH, testosterone, and AMH concentrations were measured. The effect of hormonal variables on the incidence of type 2 DM was estimated using the log-binomial model, adjusted for major confounding factors. The correlations between PRL and the indicators of glucose and lipid metabolism and other hormonal variables were also explored.

RESULTS

In the unadjusted model, PRL was not significantly associated with the incidence rate of type 2 DM (RR = 0.98, 95% CI: 0.94 - 1.03). After adjusting for potential confounders, the inverse effect of AMH on the incidence rate of type 2 DM was the only significant association. The analyses also indicated a significant positive association between PRL and LH/FSH ratio (r = 0.1, P = 0.01).

CONCLUSION

No significant association was found between serum PRL concentrations within the physiologic range and the incidence rate of type 2 diabetes mellitus among middle-aged men. Men with higher concentrations of PRL within the physiologic range tended to show higher levels of LH and LH/FSH. AMH was the only variable significantly linked to the incidence rate of type 2 DM in men.

Obesity, type 2 diabetes, and testosterone in ageing men

In the absence of obesity, adverse lifestyle behaviours, and use of medication such as opioids serum testosterone concentrations decrease by only a minimal amount at least until very advanced age in most men. Obesity is heterogeneous in its phenotype, and it is the accumulation of excess adipose tissue viscerally associated with insulin resistance, dyslipidaemia, inflammation, hypothalamic leptin resistance and gliosis that underpins the functional hypogonadism of obesity. Both central (hypothalamic) and peripheral mechanisms are involved resulting in a low serum total testosterone concentration, while LH and FSH are typically in the normal range. Peripherally a decrease in serum sex hormone binding globulin (SHBG) concentration only partially explains the decrease in testosterone and there is increasing evidence for direct effects in the testis. Men with obesity associated functional hypogonadism and serum testosterone concentrations below 16 nmol/L are at increased risk of incident type 2 diabetes (T2D); high testosterone concentrations are protective. The magnitude of weight loss is linearly associated with an increase in serum testosterone concentration and with the likelihood of preventing T2D or reverting newly diagnosed disease; treatment with testosterone for 2 years increases the probability of a positive outcome from a lifestyle intervention alone by approximately 40%. Whether the additional favourable benefits of testosterone treatment on muscle mass and strength and bone density and quality in the long-term remains to be determined.

Changes in levels of testosterone, insulin sensitivity and metabolic profiles during GnRH therapy: Reciprocity between insulin sensitivity and pituitary responsiveness to GnRH in teenage and young male patients with congenital hypogonadotropic hypogonadism

OBJECTIVES

A direct evaluation of insulin sensitivity on pituitary response to gonadotropin relasing hormone (GnRH) has not been shown in congenital hypogonadotropic hypogonadism (CHH), despite a growing body of evidence in the association of testosterone concentrations with insulin sensitiviy. The objective of the study was to explore whether increased testosterone concentrations in men with CHH improve insulin sensitivity, or vice versa.

DESIGN

A retrospective study at a tertiary centre.

PATIENTS

Series of male CHH patients were included from Jannuary 2014 to December 2019.

MEASUREMENTS

Insulin sensitivity indices calculated from oral glucose tolerance test and steroid hormone levels were examined in 52 patients with newly diagnosed CHH and 22 healthy controls. Thirty-two of the 52 CHH patients received pulsatile GnRH therapy with follow-up every 3-6 months.

RESULTS

Compared to healthy controls, CHH patients had elevated 2 h post-load glucose, HbA1c, fasting insulin, HOMA of insulin resistance (HOMA-IR) and decreased Matsuda index and testosterone (p ≤ .01). The median follow-up for patients (n = 32) who received pulsatile GnRH therapy was 13.5 (11.3-24) months (432 person-months in total). GnRH therapy increased testosterone and Matsuda index (p ≤ .0001), whilst decreased platelet count (p = .04), leptin (p = .04), fasting glucose (p = .01) and HOMA-IR (p < .0001) compared with baseline. The median treatment duration first time to reach the lower limit of normal testosterone concentrations of patients with high and low baseline insulin sensitivity was 15 (95% CI: 8.1-21.9) and 30 months (21.2-38.8), respectively. Correspondingly, after GnRH therapy, luteinizing hormone responsiveness to GnRH provocative test was more vigorous in patients with high insulin sensitivity than those with low insulin sensitivity [17.0 (9.5-25.9) vs. 8.2 (3.3-13.0), p = .01].

CONCLUSION

Pulsatile GnRH therapy elevated testosterone levels in male CHH patients, ameliorated impaired insulin sensitivity and attenuated subclinical inflammatory response, increased insulin sensitivity, in turn, may benefit the efficacy of pulsatile GnRH therapy.

Effects of androgens on glucose metabolism

Type 2 diabetes (T2D) and obesity are common and associated with increased morbidity and mortality. Cross-sectional and longitudinal studies have demonstrated a clear association between T2D, obesity and reduced total testosterone concentration. This relationship becomes less significant or absent with correction for changes in body composition, supporting the notion that changes in body composition are mediating these effects. Moreover, this mediating effect of body composition changes is bi-directional, as evidenced by interventional studies of weight loss and testosterone treatment. On the one hand, in obese men, serum testosterone increases markedly with weight loss. On the other hand, testosterone improves body composition. This relationship is driven by multiple complex interaction between obesity and insulin resistance and the hypothalamic-pituitary-testicular axis, at all levels. Data from randomised control trials have demonstrated that intervention with testosterone therapy increases muscle mass and reduces adiposity. Most recently it has been shown that treatment with testosterone prevents progression of impaired glucose tolerance to T2D, or reverses newly diagnosed T2D beyond lifestyle intervention alone. At present there are insufficient safety data to support the use of testosterone for prevention of type 2 diabetes.

Morbidity and mortality in men: Role of androgens

In this narrative review we provide an overview of the current literature on male hypogonadism and related comorbidities, also depicting the role of testosterone therapy (TTh) in the various settings. Male hypogonadism has been associated with major comorbidities such as type 2 diabetes mellitus, obesity and cardiovascular diseases, promoting a vicious cycle that may lead to further hypogonadism. The biological underpinnings of this association are currently under investigations, but clearly emerges the relevance of the hypothalamic-pituitary-gonadal axis. Hypogonadism has also been associated with increased risk of mortality. As such, TTh has the potential to oppose these patterns and improve cardiovascular and metabolic health in hypogonadal men. Clinical and observational data suggest that in males with hypogonadism, TTh, together with lifestyle changes and diabetes medications, may improve glycemia, reduce risk of progression to diabetes and provides positive effects on cardiovascular risk. Conversely, available data does not fully support any increased risk of prostate cancer in men under TTh. Of clinical relevance, a possible harmful role of hypogonadal status in men with COVID-19 eventually emerged.

The role of serum testosterone and dehydroepiandrosterone sulfate in kidney function and clinical outcomes in chronic kidney disease: a systematic review and meta-analysis

OBJECTIVE/DESIGN

Testosterone might mediate sex differences in kidney function and chronic kidney disease (CKD). However, few studies analyzing the association between testosterone and kidney function showed conflicting results. Therefore, we performed a systematic review and meta-analysis.

METHODS

Six electronic databases were searched from inception to March 4, 2020, for studies that investigated the association of (i) testosterone status with kidney function in the general population or (ii) testosterone status with clinical outcomes (kidney function decline, kidney failure, cardiovascular (CV) events, and cardiovascular and all-cause mortality) in CKD patients. We used random and fixed-effect models to obtain pooled effect estimates with 95% confidence intervals (CIs).

RESULTS

No randomized-controlled trials that met the inclusion criteria were identified. One study was conducted in the general population and reported an increased risk of incident CKD with low vs normal testosterone (hazard ratio (HR): 1.38, 95% CI: 1.05;1.80). Seven studies were conducted in men with CKD and included testosterone as determinant, of which six could be meta-analyzed. Low testosterone was associated with an increased risk of all-cause mortality and CV events (pooled HR: 1.98, 95% CI: 1.36;2.89; pooled HR of 2.40, 95% CI: 1.22;4.71, respectively). Two studies showed an increased risk of all-cause mortality with decreased dehydroepiandrosterone sulfate (DHEAS) in men with CKD; results regarding CV events were conflicting.

CONCLUSIONS

Although literature is scarce, evidence suggests that lower testosterone may increase CKD risk in the general population and risk of all-cause mortality and CV events in men with CKD. Whether testosterone supplementation could prevent these potential detrimental outcomes should be determined in future intervention studies.

Frailty and testosterone level in older adults: a systematic review and meta-analysis

PURPOSE

We conducted a systematic review to evaluate the relationship between total testosterone (TT), free testosterone (fT), or sex hormone-binding globulin (SHBG) and frailty in older adults.

METHODS

We systematically searched nine databases (e.g. MEDLINE, Embase, ACP Journal Club, and the Cochrane library et al.) for papers on frailty and androgen levels published up to October 10, 2021. We calculated the odds ratio (OR) for the relationship between testosterone level and frailty by performing meta-analysis.

RESULTS

The search strategy yielded 311 hits in all databases combined. Eleven (seven cross-sectional studies and four cohort studies) met the inclusion criteria for meta-analysis. Among cross-sectional studies, meta-analysis revealed a significant association between TT and frailty in men (OR = 1.37 [95% CI 1.09, 1.72]) not women (OR = 1.06 [0.84, 1.34]). The fT was also significantly association with frailty in men (OR = 1.55 [1.06, 2.25] not women (OR = 1.35 [0.91, 2.01]). Cohort studies showed the same result in TT (OR = 1.09 [1.02, 1.18]) and fT (OR = 1.15 [1.02, 1.30]) for men. We did not find a significant association between SHBG and frailty.

CONCLUSION

The findings of this systematic review and meta-analysis suggest that TT and fT were significantly associated with frailty in older men but not women.

Association Between Dietary Inflammatory Index and Sex Hormone Binding Globulin and Sex Hormone in U.S. Adult Females

Context

It is still unknown whether the dietary inflammatory index (DII) is associated with sex hormones and sex hormone binding globulin (SHBG) in adult women.

Objective

This study examined the association between DII and sex hormones and SHBG in U.S. adult women.

Design and Participants

This was a cross-sectional study. A total of 2,092 female participants (age ≥ 20) from the 2013–2016 National Health and Nutrition Examination Survey were enrolled. Dietary inflammatory potential was assessed by DII based on 24-h dietary recall. SHBG was assessed using immuno-antibodies and chemo-luminescence, whereas sex hormones were measured by ID-LC–MS/MS.

Results

The average DII was 0.21 ± 1.68, ranging from −4.54 (most anti-inflammatory) to 4.28 (most pro-inflammatory). After adjusting all covariates, a per-unit DII increase in DII tertile 3 was related to an 8.05 nmol/L SHBG decrease compared to DII tertile 1 (P = 0.0366). Subgroup analysis stratified by perimenopausal period found that this negative association remained strong but only existed in women before (β = −3.71, 95% CI: −7.43, −0.12, P = 0.0423) the perimenopausal period. Interaction terms were added to both subgroup analyses and found no significant heterogeneity among different body mass index (BMI) or perimenopausal groups (P > 0.05). Treshold analyses showed that the association of age with SHBG was an inverted U-shaped curve (inflection point: age = 50 yrs).

Conclusion

A proinflammatory diet caused decreased SHBG. However, more well-designed studies are still needed to validate and verify the causal relationship between DII and sex hormones and SHBG.

Testosterone, Diabetes Risk, and Diabetes Prevention in Men

Middle-aged and older men with lower testosterone concentrations are more likely to have or to develop metabolic syndrome and type 2 diabetes. Central adiposity is a risk factor for metabolic syndrome and diabetes and predisposes to lower testosterone concentrations. Conversely, testosterone treatment reduces fat mass and insulin resistance. In a randomized controlled trial of 1007 men with either impaired glucose tolerance or newly diagnosed type 2 diabetes, 2 years of testosterone treatment on a background of lifestyle intervention reduced the risk of type 2 diabetes by 40%; this demonstrates the potential utility for testosterone pharmacotherapy to prevent diabetes in men.

Prediction of Insulin Resistance and Impaired Fasting Glucose Based on Sex Hormone-Binding Globulin (SHBG) Levels in Polycystic Ovary Syndrome

OBJECTIVE

Decreased synthesis of sex hormone-binding globulin (SHBG) related to hyperinsulinemia is one of the disturbances characteristic of polycystic ovary syndrome (PCOS). Hyperinsulinemia is a compensatory mechanism for liver insulin resistance (IR); thus, SHBG may be considered as a surrogate marker of liver IR. Therefore, this study aimed to assess the prediction of IR and impaired fasting glucose (IFG) based on SHBG levels in women with PCOS.

METHODS

This analysis included data retrieved from medical records of 854 patients with PCOS hospitalized in the Gynecological Endocrinology Clinic from 2012 to 2019. Data including anthropometric parameters, fasting plasma glucose, insulin, and SHBG levels were analyzed. BMI and HOMA-IR were calculated with standard formulas.

RESULTS

IFG and IR assessed based on HOMA-IR values > 2.0 were found in 19.5% and 47.8% of the study group, respectively. Empirical optimal cutoff values for SHBG levels were ≤41.5 nmol/L typical for IR (AUC 0.711, sensitivity 61.1%, specificity 71.6%, positive predictive value (PPV) 70.7%, and negative predictive value (NPV) 62.1%). The probability of insulin resistance occurrence for SHBG concentration 26.1 nmol/L (the lower normal range) was 61.6% (95% CI: 57.4%-65.8%). The SHBG concentration of 36.4 nmol/L and 8.1 nmol/L was related to a 10% and 20% probability of IFG, respectively.

CONCLUSION

In conclusion, this is the first study estimating the probability of liver IR and IFG occurrence based on SHBG levels in women with PCOS. Despite the low sensitivity, SHBG level below 42 nmol/L should cause closer monitoring for the fatty liver and prediabetes.

Steroid profiling and genetic variants in Chinese women with gestational diabetes mellitus

Previous studies have demonstrated that steroids were associated with gestational diabetes mellitus (GDM). However, results from different studies remained inconsistent, and only a limited range of steroids were investigated in these studies. Therefore, we aimed to analyze comprehensive steroid profiling in Chinese women with GDM during third-trimester pregnancy. In 97 Chinese pregnant women, we measured steroid profile using a LC-MS/MS method, and calculated product-to-precursor ratios in metabolic pathways of steroids. Then sixteen genetic variants of genes encoding steroidogenic enzymes were genotyped by MassARRAY system. There were significant differences (P < 0.05) and obvious changes (fold change <0.67 or>1.5) in steroids (testosterone, estriol, pregnenolone and dehydroepiandrosterone) and product-to-precursor ratios (E2/T and T/AD) between GDM and control groups. After adjusting for maternal age, the TT genotype and T allele of CYP19A1 rs10046 were associated with an increased risk of GDM. And the CC genotype and C allele of HSD17B3 rs2257157 were also associated with an increased risk of GDM. Besides, pregnant women carrying TT genotype of CYP19A1 rs10046 and CC genotype of HSD17B3 rs2257157 had a lower E2/T ratio and higher T/AD ratio respectively comparing with those carrying other genotypes. In conclusion, our study suggested that testosterone, estriol, pregnenolone and dehydroepiandrosterone might be differential metabolites for gestational diabetes mellitus. The genetic variants rs10046 of CYP19A1 and rs2257157 of HSD17B3 could predispose to GDM in Chinese women.

Testosterone therapy and cardiovascular diseases

Since it was first synthesised in 1935, testosterone (T) has been viewed as the mythical Fountain of Youth, promising rejuvenation, restoring sexual appetites, growing stronger muscles, and quicker thinking. T is endowed with direct effects on myocardial and vascular structure and function, as well as on risk factors for cardiovascular (CV) disease. Indeed, low serum T levels are a risk factor for diabetes, metabolic syndrome, inflammation, and dyslipidaemia. Moreover, many studies have shown that T deficiency per se is an independent risk factor of CV and all-cause mortality. On this background and due to direct-to-patient marketing by drug companies, we have witnessed to the widespread use of T replacement therapy (TT) without clear indications particularly in late-life onset hypogonadism. The current review will dwell upon current evidence and controversies surrounding the role of T in the pathophysiology of CV diseases, the link between circulating T levels and CV risk, and the use of replacing T as a possible adjuvant treatment in specific CV disorders. Specifically, recent findings suggest that heart failure and type 2 diabetes mellitus represent two potential targets of T therapy once that a state of hypogonadism is diagnosed. However, only if ongoing studies solve the CV safety issue the T orchid may eventually 'bloom'.

Mediated relationships between multiple metals exposure and fasting blood glucose by reproductive hormones in Chinese men

Previous studies have reported metals exposure contribute to the change of fasting blood glucose (FBG) level. However, the roles of reproductive hormones in their associations have not been fully elucidated. The aim of the study is to investigate the associations of multiple serum metals with reproductive hormones, and to further explore potential roles of reproductive hormones in relationships between metals exposure and FBG level. A total of 1911 Chinese Han men were analyzed by a cross-sectional study. We measured serum levels of 22 metals by inductively coupled plasma mass spectrometer (ICP-MS). FBG, total testosterone (TT), estradiol (E2), follicle stimulating hormone (FSH), and sex hormone-binding globulin (SHBG) levels were determined. Least absolute shrinkage and selection operator (LASSO) regression models were conducted to select important metals, and restricted cubic spline models were then used to estimate dose-response relationships between selected metals and reproductive hormones. We also conducted mediation analyses to evaluate whether reproductive hormones played mediating roles in the associations between metals and FBG. We found significant inverse dose-dependent trends of copper, tin and zinc with E2; zinc with SHBG; copper and nickel with TT, while significant positive dose-dependent trend of iron with E2, respectively. Moreover, approximately inverted U-shaped associations existed between lead and SHBG, iron and TT. In addition, E2, SHBG and TT were negatively associated with FBG level. In mediation analyses, the association of copper with FBG was mediated by E2 and TT, with a mediation ratio of 10.4% and 22.1%, respectively. Furthermore, E2 and SHBG mediated the relationship of zinc with FBG, with a mediation ratio of 7.8% and 14.5%, respectively. E2 mediated 11.5% of positive relationship between tin with FBG. Our study suggested that the associations of metals exposure with FBG may be mediated by reproductive hormones.

The Cutoff Value of Low Sex Hormone-Binding Globulin and Its Predictive Role in Impaired Glucose Metabolism Among Chinese Women with Polycystic Ovarian Syndrome

Background: Low levels of sex hormone-binding globulin (SHBG) is a potential predictor of type 2 diabetes mellitus (T2DM), and when combined with insulin resistance (IR), lead to impaired glucose metabolism. Few studies involve women with polycystic ovarian syndrome (PCOS). Studies on cutoff values of SHBG among Asian women were scanty. Methods: The cutoff level of SHBG was computed using the 25th percentile method. Parameters were compared between the lower and higher SHBG subgroup. Area under the curve (AUC) for sensitivity and specificity of SHBG in predicting IR and impaired glucose metabolism was calculated. Results: This study included 733 patients with PCOS 20-45 years of age and 469 age-matched controls. The 25th percentile of SHBG in the control group was 51.90 nM. There were negative correlations between SHBG and age (r = -0.085, P < 0.05), body mass index (BMI) (r = -0.461, P < 0.01), waist-to-hip ratio (WHR) (r = -0.349, P < 0.01), fasting plasma glucose (r = -0.242, P < 0.01), Glucose-1h (r = -0.303, P < 0.01), Glucose-2h (r = -0.336, P < 0.01), fasting insulin (r = -0.324, P < 0.01), Insulin-1h (r = -0.238, P < 0.01), Insulin-2h (r = -0.307, P < 0.01), and homeostasis model 2 assessment of insulin resistance (HOMA2-IR) (r = -0.329, P < 0.01). Age, BMI, WHR, glucose and insulin levels (both pre- and postload), HOMA2-IR, free testosterone, and dehydroepiandrosterone sulfate were all higher in the lower than the higher SHBG subgroup. The AUC of SHBG for predicting IR was 0.706 [95% confidence interval (CI) 0.665-0.745, P < 0.001], impaired fasting glucose was 0.674 (95% CI 0.513-0.838, P < 0.001), impaired glucose tolerance was 0.637 (95% CI 0.586-0.690, P < 0.001), and T2DM was 0.674 (95% CI 0.556-0.780, P < 0.001). Conclusions: A 51.90 nM should be identified as the cutoff value of SHBG. Women with PCOS with lower SHBG values have a higher risk of developing impaired glucose metabolism. Low SHBG should be a predictive biomarker of impaired glucose metabolism in women with PCOS in southern China.

Testosterone treatment to prevent or revert type 2 diabetes in men enrolled in a lifestyle programme (T4DM): a randomised, double-blind, placebo-controlled, 2-year, phase 3b trial

BACKGROUND

Men who are overweight or obese frequently have low serum testosterone concentrations, which are associated with increased risk of type 2 diabetes. We aimed to determine whether testosterone treatment prevents progression to or reverses early type 2 diabetes, beyond the effects of a community-based lifestyle programme.

METHODS

T4DM was a randomised, double-blind, placebo-controlled, 2-year, phase 3b trial done at six Australian tertiary care centres. Men aged 50-74 years, with a waist circumference of 95 cm or higher, a serum testosterone concentration of 14·0 nmol/L or lower but without pathological hypogonadism, and impaired glucose tolerance (oral glucose tolerance test [OGTT] 2-h glucose 7·8-11·0 mmol/L) or newly diagnosed type 2 diabetes (provided OGTT 2-h glucose ≤15·0 mmol/L) were enrolled in a lifestyle programme and randomly assigned (1:1) to receive an intramuscular injection of testosterone undecanoate (1000 mg) or placebo at baseline, 6 weeks, and then every 3 months for 2 years. Randomisation was done centrally, including stratification by centre, age group, waist circumference, 2-h OGTT glucose, smoking, and first-degree family history of type 2 diabetes. The primary outcomes at 2 years were type 2 diabetes (2-h OGTT glucose ≥11·1 mmol/L) and mean change from baseline in 2-h OGTT glucose, assessed by intention to treat. For safety assessment, we did a masked monitoring of haematocrit and prostate-specific antigen, and analysed prespecified serious adverse events. This study is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12612000287831.

FINDINGS

Between Feb 5, 2013, and Feb 27, 2017, of 19 022 men who were pre-screened, 1007 (5%) were randomly assigned to the placebo (n=503) and testosterone (n=504) groups. At 2 years, 2-h glucose of 11·1 mmol/L or higher on OGTT was reported in 87 (21%) of 413 participants with available data in the placebo group and 55 (12%) of 443 participants in the testosterone group (relative risk 0·59, 95% CI 0·43 to 0·80; p=0·0007). The mean change from baseline 2-h glucose was -0·95 mmol/L (SD 2·78) in the placebo group and -1·70 mmol/L (SD 2·47) in the testosterone group (mean difference -0·75 mmol/L, -1·10 to -0·40; p<0·0001). The treatment effect was independent of baseline serum testosterone. A safety trigger for haematocrit greater than 54% occurred in six (1%) of 484 participants in the placebo group and 106 (22%) of 491 participants in the testosterone group, and a trigger for an increase of 0·75 μg/mL or more in prostate-specific antigen occurred in 87 (19%) of 468 participants in the placebo group and 109 (23%) of 480 participants in the testosterone group. Prespecified serious adverse events occurred in 37 (7·4%, 95% CI 5·4 to 10·0) of 503 patients in the placebo group and 55 (10·9%, 8·5 to 13·9) of 504 patients in the testosterone group. There were two deaths in each group.

INTERPRETATION

Testosterone treatment for 2 years reduced the proportion of participants with type 2 diabetes beyond the effects of a lifestyle programme. Increases in haematocrit might be treatment limiting. Longer-term durability, safety, and cardiovascular effects of the intervention remain to be further investigated.

FUNDING

Australian National Health and Medical Research Council, Bayer, Eli Lilly, University of Adelaide, and WW (formerly Weight Watchers).

Longitudinal associations between sex hormone-binding globulin and insulin resistance

PURPOSE

We aimed to investigate the association between SHBG and the homeostatic model assessment of insulin resistance (HOMA-Ir) in men and women in a prospective observational study.

METHODS

The Vara-Skövde cohort is a random population of 2816 participants living in southwestern Sweden, aged 30-74. It was recruited between 2002 and 2005, and followed up in 2012-2014. After excluding participants on insulin therapy or hormone replacement therapy, 1193 individuals (649 men, 544 women) were included in the present study. Fasting blood samples were collected at both visits and stored in biobank. All participants were physically examined by a trained nurse. SHBG was measured with immunoassay technique. Linear regressions were computed to investigate the association between SHBG and HOMA-Ir both in cross-sectional and longitudinal analyses, adjusting for confounding factors.

RESULTS

The mean follow-up time was 9.7 ± 1.4 years. Concentrations of SHBG were significantly inversely associated with log transformed HOMA-Ir in all groups with estimated standardized slopes (95% CI): men: -0.20 (-0.3;-0.1), premenopausal women: -0.26 (-0.4;-0.2), postmenopausal women: -0.13 (-0.3;-0.0) at visit 1. At visit 2 the results were similar. When comparing the groups, a statistically significant difference was found between men and post-menopausal women (0.12 (0.0;0.2) P value = 0.04). In the fully adjusted model, SHBG at visit 1 was also associated with HOMA-Ir at visit 2, and the estimated slopes were -0.16 (-0.2;-0.1), -0.16 (-0.3;-0.1) and -0.07 (-0.2;0.0) for men, premenopausal and postmenopausal women, respectively.

MAIN CONCLUSION

Levels of SHBG predicted the development of insulin resistance in both men and women, regardless of menopausal state.

Systematic review with meta-analysis of the epidemiological evidence relating smoking to type 2 diabetes

BACKGROUND

Evidence relating tobacco smoking to type 2 diabetes has accumulated rapidly in the last few years, rendering earlier reviews considerably incomplete.

AIM

To review and meta-analyse evidence from prospective studies of the relationship between smoking and the onset of type 2 diabetes.

METHODS

Prospective studies were selected if the population was free of type 2 diabetes at baseline and evidence was available relating smoking to onset of the disease. Papers were identified from previous reviews, searches on Medline and Embase and reference lists. Data were extracted on a range of study characteristics and relative risks (RRs) were extracted comparing current, ever or former smokers with never smokers, and current smokers with non-current smokers, as well as by amount currently smoked and duration of quitting. Fixed- and random-effects estimates summarized RRs for each index of smoking overall and by various subdivisions of the data: Sex; continent; publication year; method of diagnosis; nature of the baseline population (inclusion/exclusion of pre-diabetes); number of adjustment factors; cohort size; number of type 2 diabetes cases; age; length of follow-up; definition of smoking; and whether or not various factors were adjusted for. Tests of heterogeneity and publication bias were also conducted.

RESULTS

The literature searches identified 157 relevant publications providing results from 145 studies. Fifty-three studies were conducted in Asia and 53 in Europe, with 32 in North America, and seven elsewhere. Twenty-four were in males, 10 in females and the rest in both sexes. Fifteen diagnosed type 2 diabetes from self-report by the individuals, 79 on medical records, and 51 on both. Studies varied widely in size of the cohort, number of cases, length of follow-up, and age. Overall, random-effects estimates of the RR were 1.33 [95% confidence interval (CI): 1.28-1.38] for current vs never smoking, 1.28 (95%CI: 1.24-1.32) for current vs non-smoking, 1.13 (95%CI: 1.11-1.16) for former vs never smoking, and 1.25 (95%CI: 1.21-1.28) for ever vs never smoking based on, respectively, 99, 156, 100 and 100 individual risk estimates. Risk estimates were generally elevated in each subdivision of the data by the various factors considered (exceptions being where numbers of estimates in the subsets were very low), though there was significant (P < 0.05) evidence of variation by level for some factors. Dose-response analysis showed a clear trend of increasing risk with increasing amount smoked by current smokers and of decreasing risk with increasing time quit. There was limited evidence of publication bias.

CONCLUSION

The analyses confirmed earlier reports of a modest dose-related association of current smoking and a weaker dose-related association of former smoking with type 2 diabetes risk.

Androgen-Regulated Cardiac Metabolism in Aging Men

The prevalence of cardiovascular mortality is higher in men than in age-matched premenopausal women. Gender differences are linked to circulating sex-related steroid hormone levels and their cardio-specific actions, which are critical factors involved in the prevalence and features of age-associated cardiovascular disease. In women, estrogens have been described as cardioprotective agents, while in men, testosterone is the main sex steroid hormone. The effects of testosterone as a metabolic regulator and cardioprotective agent in aging men are poorly understood. With advancing age, testosterone levels gradually decrease in men, an effect associated with increasing fat mass, decrease in lean body mass, dyslipidemia, insulin resistance and adjustment in energy substrate metabolism. Aging is associated with a decline in metabolism, characterized by modifications in cardiac function, excitation-contraction coupling, and lower efficacy to generate energy. Testosterone deficiency -as found in elderly men- rapidly becomes an epidemic condition, associated with prominent cardiometabolic disorders. Therefore, it is highly probable that senior men showing low testosterone levels will display symptoms of androgen deficiency, presenting an unfavorable metabolic profile and increased cardiovascular risk. Moreover, recent reports establish that testosterone replacement improves cardiomyocyte bioenergetics, increases glucose metabolism and reduces insulin resistance in elderly men. Thus, testosterone-related metabolic signaling and gene expression may constitute relevant therapeutic target for preventing, or treating, age- and gender-related cardiometabolic diseases in men. Here, we will discuss the impact of current evidence showing how cardiac metabolism is regulated by androgen levels in aging men.

The Role of Diet and Weight Loss in Improving Secondary Hypogonadism in Men with Obesity with or without Type 2 Diabetes Mellitus

Despite growing recognition of the issue, obesity represents one of the most common public health problems, and its rates are still increasing globally. Among the number of comorbidities and complications associated with obesity, hypogonadism is listed, and this disorder, although frequently neglected, is characterized by a relevant impact on both quality of life and life expectancy. It is generally accepted that hypogonadism secondary to obesity is functional since it is reversible following weight loss. This review summarizes all current research examining the bidirectional relationship between excess body weight and low testosterone levels. Specifically, it evaluates the role that diet, with or without physical activity, plays in improving body weight and hypogonadism in adult and elderly men with obesity, with or without type 2 diabetes mellitus.

Higher Serum Sex Hormone-Binding Globulin Levels Are Associated With Incident Cardiovascular Disease in Men

CONTEXT

Sex hormone-binding globulin (SHBG) levels are associated with cardiovascular disease (CVD) risk factors. However, prospective data on the association between SHBG levels and CVD events are sparse, with conflicting results.

OBJECTIVES

To examine associations between serum SHBG, total testosterone (TT), and incident CVD and CVD-related mortality in middle-aged to elderly men.

DESIGN AND METHODS

Data on 2563 community-dwelling men (35 to 80 years) were obtained from participants in the Men Androgen Inflammation Lifestyle Environment and Stress cohort. The analytic sample included 1492 men without baseline (2002 to 2007) CVD and with fasted morning serum SHBG and TT available at both baseline and follow-up (2007 to 2010) and without medications affecting TT or SHBG. Associations of baseline SHBG and TT, with incident CVD and CVD mortality, were analyzed using logistic regression for incident CVD and Cox proportional hazard regression for CVD mortality, adjusting for established CVD risk factors.

RESULTS

In multivariable models, elevated baseline SHBG and lower baseline TT were independently associated with incident CVD (SHBG: OR, 1.54; 95% CI, 1.15 to 2.06 per SD increase in SHBG, P = 0.003; TT: OR, 0.71; 95% CI, 0.52 to 0.97 per SD decrease in TT; P = 0.03). A decrease in TT between time points was associated with incident CVD (OR, 0.72; 95% CI, 0.56 to 0.92; P = 0.01). Neither SHBG nor TT was significantly associated with all-age CVD mortality [hazard ratio (HR), 0.69; 95% CI, 0.29 to 1.63; P = 0.40; and HR, 0.60; 95% CI, 0.28 to 1.26; P = 0.18, respectively].

CONCLUSIONS

Among all men and men >65 years, elevated SHBG and lower TT were independently associated with both a greater risk of CVD and an increased CVD mortality risk.

Androgen profile in young females with insulin resistance; the importance of 17-Hydroxyprogesterone

Considerable researches on sex steroids and insulin action have suggested a mutual interaction between hyperandrogenemia and insulin resistance (IR). The objective of present study was to evaluate the androgens levels in young females with emphasis on the association of 17OHP with IR. Serum concentrations of glucose, insulin, and androgens in 80 young females were measured by standard routine procedures. Total testosterone (TT), dihydrotestosterone (DHT), dehydroepiandrosterone sulfate (DHEAS), androstenedione (ASD), and 17-hydroxyprogesterone (17OHP) levels were higher in patients with IR compared to healthy controls (p < .05). 17OHP was associated with IR and other androgens tested in young females. According to the results, androgen excess was associated with IR in young females and TT appeared to be independent predictor of IR in these patients. These data may suggest that simultaneous quantification of an androgen profile including at least TT, DHT, and 17OHP can present useful clinical information for assessment of androgen excess.

Testosterone Therapy in Men With Hypogonadism Prevents Progression From Prediabetes to Type 2 Diabetes: Eight-Year Data From a Registry Study

OBJECTIVE

Type 2 diabetes (T2D) is a public health threat. Prediabetes represents a window of opportunity for intervention to prevent T2D. Men with T2D and prediabetes often have low testosterone. Since testosterone improves glycemic control in T2D, we investigated whether testosterone therapy (TTh) in men with hypogonadism and prediabetes prevents progression to T2D.

RESEARCH DESIGN AND METHODS

Three hundred and sixteen men with prediabetes (defined as HbA_1c 5.7-6.4%) and total testosterone levels ≤12.1 nmol/L combined with symptoms of hypogonadism were analyzed. Two hundred and twenty-nine men received parenteral testosterone undecanoate (T-group), and 87 men with hypogonadism served as untreated control subjects. Metabolic and anthropometric parameters were measured twice yearly for 8 years.

RESULTS

HbA_1c decreased by 0.39 ± 0.03% (P < 0.0001) in the T-group and increased by 0.63 ± 0.1% (P < 0.0001) in the untreated group. In the T-group, 90% achieved normal glucose regulation (HbA_1c <5.7%). In the untreated group, 40.2% progressed to T2D (HbA_1c >6.5%). TTh was also associated with significant improvements in fasting glucose, triglyceride:HDL ratio, triglyceride-glucose index, lipid accumulation product, total cholesterol, LDL, HDL, non-HDL, triglycerides, and Aging Males' Symptoms (AMS) scale. Significant deterioration in all these parameters was seen in the untreated group. Mortality was 7.4% in the T-group and 16.1% in the untreated group (P < 0.05). The incidence of nonfatal myocardial infarction was 0.4% in the T-group and 5.7% in the untreated group (P < 0.005).

CONCLUSIONS

Long-term TTh completely prevents prediabetes progression to T2D in men with hypogonadism and improves glycemia, lipids, and AMS score. TTh holds tremendous potential for the large and growing population of men with prediabetes and hypogonadism.

Anti-Müllerian Hormone Levels and Cardiometabolic Disturbances by Weight Status Among Men in the 1999 to 2004 National Health and Nutrition Examination Survey

Context

Serum anti-Müllerian hormone level (AMH) and body mass index may be jointly associated with cardiometabolic risk.

Objectives

Examine the contribution of AMH to cardiometabolic disturbances by weight status among US adult men.

Design

Cross-sectional analysis using data from the 1999 to 2004 waves of the National Health and Nutrition Examination Survey.

Setting

Multistage probability sampling of the noninstitutionalized US population.

Participants

US men aged ≥18 years. Final analytic sample sizes ranged from 517 to 1063 participants.

Main Outcome and Exposure Measures

Cardiometabolic disturbances (metabolic syndrome and its components, insulin resistance, diabetes, and chronic inflammation) and AMH were obtained from trained staff and nurses in a mobile examination center or during in-home visits.

Results

AMH was directly associated with insulin resistance among obese men [OR 1.08 (95% CI 1.00, 1.15); P = 0.046; N = 146], whereas AMH was inversely associated with waist circumference (WC) among obese men [OR 0.95 (95% CI 0.91, 0.99); P = 0.049; N = 146]. An inverse relationship was also observed between categorical AMH and diabetes status [medium vs low AMH; OR 0.19 (95% CI 0.043, 0.84); P = 0.030; N = 145] among obese men, with a strong inverse relationship also detected among overweight men [high vs low AMH; OR 0.011 (95% CI 0.0004, 0.27); P = 0.007; N = 193]. An inverse relationship between continuous AMH and diabetes [OR 0.75 (95% CI: 0.59, 0.93); P = 0.011; N = 193] was also detected among overweight men.

Conclusions

AMH was associated with specific cardiometabolic risk factors, including WC, diabetes status, and insulin resistance, in overweight and obese US men.

Sex hormones, obesity and type 2 diabetes: is there a link?

An imbalance in sex hormones has an important impact on type 2 diabetes (T2DM) mainly through the involvement of visceral adipose tissue. Androgens have an interesting sex-dimorphic association with T2DM, since hyperandrogenism in females and hypogonadism in males are risk factors for T2DM. Thus, treatments aimed at correcting hyperandrogenism in females and hypogonadism in males may prevent the development of T2DM or help in its treatment.

Malignancy incidences by glycemic control among diabetic patients

BACKGROUND

The aim of this study was to evaluate the difference in malignancy incidence by evaluating time-dependent HbA1c levels among diabetic patients in a longitudinal study.

METHODS

We conducted a retrospective longitudinal study at large academic hospital, Tokyo, Japan, from 2006 to 2016. We included all diabetic patients who were 50 years or older and who underwent health check-ups at the Center for Preventive Medicine. Those patients with a prior history of malignancies were excluded. We categorized patients into five groups on the basis of HbA1c measurements: <5.4, 5.5-6.4, 6.5-7.4, 7.5-8.5, >8.5%. Our primary outcome was the development of any types of malignancy. Longitudinal analyses by a mixed effect model with time-dependent HbA1c levels were applied in order to take into account fluctuations in HbA1c levels within the same patient.

RESULTS

In total, 2729 participants were included in this study, where the mean age was 62.6 (standard deviation (s.d.): 7.8) and 2031 (74.4%) were male. The mean disease duration of diabetes was 7.6 (s.d.: 7.6) years, and 1688 (61.8%) were prescribed medications. Median follow-up was 1443.5 (interquartile range (IQR): 2508) days and 376 (13.8%) developed malignancies. Compared to the reference range of HbA1c (5.5-6.4%), the odds ratios for developing malignancies among the other HbA1c level groups were similar and not statistically different (OR: 0.98, 95% CI:0.31-3.15 (for HbA1c <5.4%); OR: 0.88, 95% CI: 0.69-1.12 (for HbA1c 6.5-7.4%); OR: 0.88, 95% CI: 0.64-1.22 (for HbA1c 7.5-8.4%); OR 1.07, 95% CI: 0.70-1.66 (for HbA1c >8.5%)).

CONCLUSION

In our study, there was no association between glycemic control and the development of future malignancies. Compared to very strictly controlled HbA1c levels, both excessive control and good or bad control had a statistically similar risk of developing malignancies.

The association between serum testosterone and insulin resistance: a longitudinal study

The objective of this study was to investigate whether there is a bidirectional association between testosterone concentrations and insulin resistance, in a prospective population study. A random population sample of 1400 men, aged 30-74, was examined in 2002-2005 in southwestern Sweden and followed up in 2012-2014 (N = 657). After excluding subjects without information on sex hormones and insulin resistance, 1282 men were included in the baseline study. Fasting measurements of plasma glucose, insulin and hormones were performed. Insulin resistance was defined using HOMA-Ir. Mean age at baseline was 47.3 ± 11.4 years. From the follow-up survey 546 men were included, mean age 57.7 ± 11.6 years. Low concentrations of total testosterone at baseline were significantly associated with high logHOMA-Ir at follow-up in a multivariable model including age, waist-hip ratio, physical activity, alcohol intake, smoking, LDL, CRP, hypertension, diabetes and logHOMA-Ir at baseline as covariates (β = -0.096, P = 0.006). Similar results were observed for bioavailable testosterone. Men within the lowest quartile of total testosterone at baseline had significantly higher logHOMA-Ir at follow-up than other quartiles (Q1 vs Q2 P = 0.008, Q1 vs Q3 P = 0.001, Q1 vs Q4 P = 0.052). Multivariable analysis of the impact of insulin resistance at baseline on testosterone levels at follow-up revealed no significant associations regarding testosterone concentrations (β = -0.003, P = 0.928) or bioavailable testosterone (β = -0.006, P = 0.873), when adjusting for baseline concentrations of total testosterone, age, waist-hip-ratio, LDL, CRP, physical activity, alcohol intake, smoking, hypertension and diabetes. Low testosterone concentrations at baseline predicted higher insulin resistance at follow-up, but high insulin resistance at baseline could not predict low testosterone at follow-up.

Cross-sectional and longitudinal determinants of serum sex hormone binding globulin (SHBG) in a cohort of community-dwelling men

Despite its widespread clinical use, there is little data available from population-based studies on the determinants of serum sex hormone binding globulin (SHBG). We aimed to examine multifactorial determinants of circulating SHBG levels in community-dwelling men. Study participants comprised randomly selected 35–80 y.o. men (n = 2563) prospectively-followed for 5 years (n = 2038) in the Men Androgen Inflammation Lifestyle Environment and Stress (MAILES) study. After excluding men with illness or medications known to affect SHBG (n = 172), data from 1786 men were available at baseline, and 1476 at follow-up. The relationship between baseline body composition (DXA), serum glucose, insulin, triglycerides, thyroxine (fT4), sex steroids (total testosterone (TT), oestradiol (E2)), and pro-inflammatory cytokines and serum SHBG level at both baseline & follow-up was determined by linear and penalized logistic regression models adjusting for age, lifestyle & demographic, body composition, metabolic, and hormonal factors. Restricted cubic spline analyses was also conducted to capture possible non-linear relationships. At baseline there were positive cross-sectional associations between age (β = 0.409, p<0.001), TT (β = 0.560, p<0.001), fT4 (β = 0.067, p = 0.019) and SHBG, and negative associations between triglycerides (β = -0.112, p<0.001), abdominal fat mass (β = -0.068, p = 0.032) and E2 (β = -0.058, p = 0.050) and SHBG. In longitudinal analysis the positive determinants of SHBG at 4.9 years were age (β = 0.406, p = <0.001), TT (β = 0.461, p = <0.001), and fT4 (β = 0.040, p = 0.034) and negative determinants were triglycerides (β = -0.065, p = 0.027) and abdominal fat mass (β = -0.078, p = 0.032). Taken together these data suggest low SHBG is a marker of abdominal obesity and increased serum triglycerides, conditions which are known to have been associated with low testosterone and low T4.