Sex hormone-binding globulin associations with circulating lipids and metabolites and the risk for type 2 diabetes: observational and causal effect estimates

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.

Protective Effect of Sex Hormone-Binding Globulin against Metabolic Syndrome: In Vitro Evidence Showing Anti-Inflammatory and Lipolytic Effects on Adipocytes and Macrophages

Sex hormone-binding globulin (SHBG) is a serum protein released mainly by the liver, and a low serum level correlates with a risk for metabolic syndrome including diabetes, obesity, and cardiovascular events. However, the underlying molecular mechanism(s) linking SHBG and metabolic syndrome remains unknown. In this study, using adipocytes and macrophages, we focused on the in vitro effects of SHBG on inflammation as well as lipid metabolism. Incubation with 20 nM SHBG markedly suppressed lipopolysaccharide- (LPS-) induced inflammatory cytokines, such as MCP-1, TNFα, and IL-6 in adipocytes and macrophages, along with phosphorylations of JNK and ERK. Anti-inflammatory effects were also observed in 3T3-L1 adipocytes cocultured with LPS-stimulated macrophages. In addition, SHBG treatment for 18 hrs or longer significantly induced the lipid degradation of differentiated 3T3-L1 cells, with alterations in its corresponding gene and protein levels. Notably, these effects of SHBG were not altered by coaddition of large amounts of testosterone or estradiol. In conclusion, SHBG suppresses inflammation and lipid accumulation in macrophages and adipocytes, which might be among the mechanisms underlying the protective effect of SHBG, that is, its actions which reduce the incidence of metabolic syndrome.

Prioritising Risk Factors for Type 2 Diabetes: Causal Inference through Genetic Approaches

PURPOSE OF THE REVIEW

Causality has been demonstrated for few of the many putative risk factors for type 2 diabetes (T2D) emerging from observational epidemiology. Genetic approaches are increasingly being used to infer causality, and in this review, we discuss how genetic discoveries have shaped our understanding of the causal role of factors associated with T2D.

RECENT FINDINGS

Genetic discoveries have led to the identification of novel potential aetiological factors of T2D, including the protective role of peripheral fat storage capacity and specific metabolic pathways, such as the branched-chain amino acid breakdown. Consideration of specific genetic mechanisms contributing to overall lipid levels has suggested that distinct physiological processes influencing lipid levels may influence diabetes risk differentially. Genetic approaches have also been used to investigate the role of T2D and related metabolic traits as causal risk factors for other disease outcomes, such as cancer, but comprehensive studies are lacking. Genome-wide association studies of T2D and metabolic traits coupled with high-throughput molecular phenotyping and in-depth characterisation and follow-up of individual loci have provided better understanding of aetiological factors contributing to T2D.

Metabolic characterization of menopause: cross-sectional and longitudinal evidence

BACKGROUND

Women who experience menopause are at higher cardiometabolic risk and often display adverse changes in metabolic biomarkers compared with pre-menopausal women. It remains elusive whether the changes in cardiometabolic biomarkers during the menopausal transition are due to ovarian aging or chronological aging. Well-conducted longitudinal studies are required to determine this. The aim of this study was to explore the cross-sectional and longitudinal associations of reproductive status, defined according to the 2012 Stages of Reproductive Aging Workshop criteria, with 74 metabolic biomarkers, and establish whether any associations are independent of age-related changes.

METHODS

We determined cross-sectional associations of reproductive status with metabolic profiling in 3,312 UK midlife women. In a subgroup of 1,492 women who had repeat assessments after 2.5 years, we assessed how the change in reproductive status was associated with the changes in metabolic biomarkers. Metabolic profiles were measured by high-throughput quantitative nuclear magnetic resonance metabolomics. In longitudinal analyses, we compared the change in metabolic biomarkers for each reproductive-status category change to that of the reference of being pre-menopausal at both time points. As all women aged by a similar amount during follow-up, these analyses contribute to distinguishing age-related changes from those related to change in reproductive status.

RESULTS

Consistent cross-sectional and longitudinal associations of menopause with a wide range of metabolic biomarkers were observed, suggesting the transition to menopause induces multiple metabolic changes independent of chronological aging. The metabolic changes included increased concentrations of very small very low-density lipoproteins, intermediate-density lipoproteins, low-density lipoproteins (LDLs), remnant, and LDL cholesterol, and reduced LDL particle size, all toward an atherogenic lipoprotein profile. Increased inflammation was suggested via an inflammatory biomarker, glycoprotein acetyls, but not via C-reactive protein. Also, levels of glutamine and albumin increased during the transition. Most of these metabolic changes seen at the time of becoming post-menopausal remained or became slightly stronger during the post-menopausal years.

CONCLUSIONS

The transition to post-menopause has effects on multiple circulating metabolic biomarkers, over and above the underlying age trajectory. The adverse changes in multiple apolipoprotein-B-containing lipoprotein subclasses and increased inflammation may underlie women's increased cardiometabolic risk in their post-menopausal years.

Human sex hormone-binding globulin does not provide metabolic protection against diet-induced obesity and dysglycemia in mice

BACKGROUND

Sex hormone-binding globulin (SHBG) is the main transporter of sex hormones in most vertebrates. Low SHBG levels have been linked to increased risk for diabetes and metabolic syndrome. Polymorphisms of the SHBG gene linked to low SHBG protein levels also strongly predicted increased risk of type 2 diabetes, thus raising the possibility that SHBG may play a role in the pathogenesis of insulin resistance and diabetes.

AIM

To examine whether expression of human SHBG in mice may ameliorate the development of diabetes and metabolic syndrome in response to a high-fat diet (HFD).

METHODS

Transgene mice expressing a human SHBG transgene (SHBG+) (N = 10/11; males/females) and their wild type littermates (N = 12/8; males/females) were fed HFD for 4.5 months.

RESULTS

HFD induced comparable obesity in control and SHBG+ mice. Male transgenes had higher muscle mass after 2-3.5 months HFD (0.43 ± 0.028 (n = 4) vs 0.38 ± 0.053 g (n = 7), P = 0.05). Fasting blood glucose, as well as insulin or HOMA-IR, was not different in transgenic vs wild-type males after 4-5 months HFD. Female transgenes had higher fasting glucose (152 ± 29 (n = 7) vs 115 ± 27 mg/dL, P = 0.01 (n = 8)), but mean insulin and HOMA-IR were not different. Likewise, insulin tolerance test and intra-peritoneal glucose tolerance test (GTT) were not different. Finally, SHBG+ mice were not different from controls in terms of liver enzymes, serum triglyceride levels and blood pressure.

CONCLUSION

In mice with diet-induced obesity, human SHBG did not protect against development of obesity or dysglycemia.

Impact of Metabolic Syndrome Factors on Testosterone and SHBG in Type 2 Diabetes Mellitus and Metabolic Syndrome

OBJECTIVE

Several studies have often reported low testosterone and SHBG to be associated with type 2 DM and the metabolic syndrome (MetS). Our objective was to determine the impact of metabolic syndrome and diabetic parameters on testosterone and SHBG in both MetS subjects and type 2 DM patients.

METHODS

In this study, 120 Yemeni male aged 30-70 years old were enrolled, 30 of whom were healthy subjects with BMI < 25 kg/m² that served as control, 30 MetS, 30 type 2 DM without MetS, and 30 type 2 DM with MetS according to IDF criteria.

RESULTS

Testosterone (free and total) and SHBG were significantly lower in MetS subjects and modestly reduced in type 2 DM with and without MetS. Stepwise linear regression showed free and total testosterone to be negatively affected by waist circumference, and univariate analysis shows this significant difference to disappear when adjusted for waist circumference. On the other hand, stepwise linear regression showed SHBG to be positively affected by testosterone and age and negatively affected by FBG and TG. Univariate analysis shows this observed significant difference to disappear when adjusted for testosterone.

CONCLUSION

Abdominal obesity is a major determinant of low testosterone levels irrespective of diabetes status. Thus, supporting evidence suggesting that the causative relationship between the often low testosterone and type 2 DM might be bidirectional or even multidirectional and interrelated with obesity, MetS, and IR.

Circulating sex hormones in relation to anthropometric, sociodemographic and behavioural factors in an international dataset of 12,300 men

INTRODUCTION

Sex hormones have been implicated in the etiology of a number of diseases. To better understand disease etiology and the mechanisms of disease-risk factor associations, this analysis aimed to investigate the associations of anthropometric, sociodemographic and behavioural factors with a range of circulating sex hormones and sex hormone-binding globulin.

METHODS

Statistical analyses of individual participant data from 12,330 male controls aged 25-85 years from 25 studies involved in the Endogenous Hormones Nutritional Biomarkers and Prostate Cancer Collaborative Group. Analysis of variance was used to estimate geometric means adjusted for study and relevant covariates.

RESULTS

Older age was associated with higher concentrations of sex hormone-binding globulin and dihydrotestosterone and lower concentrations of dehydroepiandrosterone sulfate, free testosterone, androstenedione, androstanediol glucuronide and free estradiol. Higher body mass index was associated with higher concentrations of free estradiol, androstanediol glucuronide, estradiol and estrone and lower concentrations of dihydrotestosterone, testosterone, sex hormone-binding globulin, free testosterone, androstenedione and dehydroepiandrosterone sulfate. Taller height was associated with lower concentrations of androstenedione, testosterone, free testosterone and sex hormone-binding globulin and higher concentrations of androstanediol glucuronide. Current smoking was associated with higher concentrations of androstenedione, sex hormone-binding globulin and testosterone. Alcohol consumption was associated with higher concentrations of dehydroepiandrosterone sulfate, androstenedione and androstanediol glucuronide. East Asians had lower concentrations of androstanediol glucuronide and African Americans had higher concentrations of estrogens. Education and marital status were modestly associated with a small number of hormones.

CONCLUSION

Circulating sex hormones in men are strongly associated with age and body mass index, and to a lesser extent with smoking status and alcohol consumption.

Cross-sectional study of the determinants and associations of sex hormone-binding globulin concentrations in first degree relatives (FDR) of patients with Type 2 Diabetes Mellitus

AIMS

This study explores the determinants of sex hormone binding globulin (SHBG) and associations with categories of glucose intolerance and undiagnosed diabetes in first-degree relatives (FDR) of patients with Type 2 Diabetes Mellitus (T2D).

METHODS

Anthropometric indices, fasting lipids, glucose, insulin, adiponectin, leptin, SHBG, estradiol (E2), testosterone (TT), androstenedione (AND), dehydroepiandrosterone sulphate (DHEA-S), high-sensitivity C-reactive protein (hs-CRP) and alanine aminotransferase (ALT) were measured in 584 FDR. Homeostasis model assessment-estimate of insulin resistance (HOMA-IR), beta cell function (%B), insulin sensitivity (%S) and free androgen index (FAI) were calculated.

RESULTS

266 subjects were normoglycemic; 237 had prediabetes and 81 had undiagnosed diabetes. SHBG decreased stepwise with worsening categories of glucose intolerance in females whereas FAI decreased stepwise with worsening categories in males only. SHBG showed significant positive correlations with adiponectin, and HDL-C and significant negative correlations with body mass index (BMI), waist circumference (WC), Waist:hip ratio (WHR), ALT, triglycerides (TG), %B, leptin and FAI. After adjustment for WHR, only HDL-C and FAI in men and FAI and HbA1c in females remained significantly associated with SHBG. Receiver Operating Characteristic (ROC) curve analysis for detection of diabetes showed that areas under the curve for FAI and SHBG were 0.711 and 0.386 for males and 0.430 and 0.660 for females respectively.

CONCLUSION

Associations of SHBG with some anthropometric and metabolic variables in FDR suggests that lower levels is a marker for risk of developing T2D through obesity dependent metabolic pathways but low FAI is a better marker of state of diabetes in males.

Cross-sectional association of coffee and caffeine consumption with sex hormone-binding globulin in healthy nondiabetic women

OBJECTIVE

Low sex hormone-binding globulin (SHBG) is a consistent risk factor for type 2 diabetes, particularly in women. Coffee consumption has been associated with a lower risk of type 2 diabetes, but its effects on SHBG are less known.

DESIGN AND METHODS

This was a cross-sectional study of 2377 nondiabetic pre- and postmenopausal women from the E3N cohort study whose baseline SHBG was measured. Information on diet (including coffee and caffeine consumption), lifestyle and medical conditions was collected through questionnaires. The relationship between coffee and caffeine consumption and SHBG was modelled, with adjustment for covariates and stratification by body mass index (BMI) categories (< or ≥25 kg/m² ) and menopausal status.

RESULTS

The mean age was 57.2±6.4 years and 61% of the 2377 women were postmenopausal. High coffee (≥3 cups/day) and caffeine (≥265 mg/day) intakes were associated with a reduced risk of being in the 1st quartile of the SHBG level distribution (<46.3 nmol/L) in a multivariate adjusted model (OR: 0.72 [95% CI: 0.52-1.01] and OR: 0.71 [95% CI: 0.53-0.95], respectively). No association was found between tea consumption and SHBG levels. In multivariate models stratified on BMI categories and menopausal status, associations were restricted to women with a BMI ≥25 kg/m² or being postmenopausal. The association with SHBG was consistently noted with consumption of both caffeinated coffee and caffeine, but not decaffeinated coffee.

CONCLUSIONS

Consumption of high coffee and caffeine is associated with a reduced risk of low SHBG, an established risk marker for T2DM, which might contribute to the protective effects of coffee for type 2 diabetes.

Quantitative Serum Nuclear Magnetic Resonance Metabolomics in Large-Scale Epidemiology: A Primer on -Omic Technologies

Detailed metabolic profiling in large-scale epidemiologic studies has uncovered novel biomarkers for cardiometabolic diseases and clarified the molecular associations of established risk factors. A quantitative metabolomics platform based on nuclear magnetic resonance spectroscopy has found widespread use, already profiling over 400,000 blood samples. Over 200 metabolic measures are quantified per sample; in addition to many biomarkers routinely used in epidemiology, the method simultaneously provides fine-grained lipoprotein subclass profiling and quantification of circulating fatty acids, amino acids, gluconeogenesis-related metabolites, and many other molecules from multiple metabolic pathways. Here we focus on applications of magnetic resonance metabolomics for quantifying circulating biomarkers in large-scale epidemiology. We highlight the molecular characterization of risk factors, use of Mendelian randomization, and the key issues of study design and analyses of metabolic profiling for epidemiology. We also detail how integration of metabolic profiling data with genetics can enhance drug development. We discuss why quantitative metabolic profiling is becoming widespread in epidemiology and biobanking. Although large-scale applications of metabolic profiling are still novel, it seems likely that comprehensive biomarker data will contribute to etiologic understanding of various diseases and abilities to predict disease risks, with the potential to translate into multiple clinical settings.

Follicle-Stimulating Hormone, Its Association with Cardiometabolic Risk Factors, and 10-Year Risk of Cardiovascular Disease in Postmenopausal Women

BACKGROUND

Cardiovascular disease is the leading cause of mortality in postmenopausal women. Follicle-stimulating hormone (FSH) shows negative associations with obesity and diabetes mellitus in postmenopausal women. We aimed to study the associations between FSH and 10-year risk of atherosclerotic cardiovascular disease (ASCVD) in postmenopausal women.

METHODS AND RESULTS

SPECT-China (the Survey on Prevalence in East China for Metabolic Diseases and Risk Factors) is a 22-site, population-based study conducted during 2014-2015. This study included 2658 postmenopausal women. A newly developed effective tool for 10-year ASCVD risk prediction among Chinese was adopted. Regression analyses were performed to assess the relationship among FSH, 10-year ASCVD risk, and multiple cardiometabolic risk factors. With the increase in FSH quartiles, the mean 10-year ASCVD risk in postmenopausal women decreased from 4.9% to 3.3%, and most metabolic parameters were significantly ameliorated (all P for trend <0.05). In regression analyses, a 1-SD increment in ln-FSH was negatively associated with continuous (B -0.12, 95% confidence interval, -0.16, -0.09, P<0.05) and categorical (odds ratio 0.65, 95% confidence interval, 0.49, 0.85, P<0.05) 10-year ASCVD risk. These significant associations existed in subgroups with or without medication use, obesity, diabetes mellitus, hypertension, and dyslipidemia. Body mass index and waist circumference (both B -0.35, 95% confidence interval, -0.40, -0.30, P<0.05) had the largest associations of all metabolic measures, and blood pressure had the smallest association.

CONCLUSIONS

Serum FSH levels were negatively associated with 10-year ASCVD risk in postmenopausal women. Among cardiometabolic factors, obesity indices had the largest associations with FSH. These results indicated that a low FSH might be a risk factor or a biomarker for cardiovascular disease risk in postmenopausal women.

Association of pre-pregnancy body mass index with offspring metabolic profile: Analyses of 3 European prospective birth cohorts

BACKGROUND

A high proportion of women start pregnancy overweight or obese. According to the developmental overnutrition hypothesis, this could lead offspring to have metabolic disruption throughout their lives and thus perpetuate the obesity epidemic across generations. Concerns about this hypothesis are influencing antenatal care. However, it is unknown whether maternal pregnancy adiposity is associated with long-term risk of adverse metabolic profiles in offspring, and if so, whether this association is causal, via intrauterine mechanisms, or explained by shared familial (genetic, lifestyle, socioeconomic) characteristics. We aimed to determine if associations between maternal body mass index (BMI) and offspring systemic cardio-metabolic profile are causal, via intrauterine mechanisms, or due to shared familial factors.

METHODS AND FINDINGS

We used 1- and 2-stage individual participant data (IPD) meta-analysis, and a negative-control (paternal BMI) to examine the association between maternal pre-pregnancy BMI and offspring serum metabolome from 3 European birth cohorts (offspring age at blood collection: 16, 17, and 31 years). Circulating metabolic traits were quantified by high-throughput nuclear magnetic resonance metabolomics. Results from 1-stage IPD meta-analysis (N = 5327 to 5377 mother-father-offspring trios) showed that increasing maternal and paternal BMI was associated with an adverse cardio-metabolic profile in offspring. We observed strong positive associations with very-low-density lipoprotein (VLDL)-lipoproteins, VLDL-cholesterol (C), VLDL-triglycerides, VLDL-diameter, branched/aromatic amino acids, glycoprotein acetyls, and triglycerides, and strong negative associations with high-density lipoprotein (HDL), HDL-diameter, HDL-C, HDL2-C, and HDL3-C (all P < 0.003). Slightly stronger magnitudes of associations were present for maternal compared with paternal BMI across these associations; however, there was no strong statistical evidence for heterogeneity between them (all bootstrap P > 0.003, equivalent to P > 0.05 after accounting for multiple testing). Results were similar in each individual cohort, and in the 2-stage analysis. Offspring BMI showed similar patterns of cross-sectional association with metabolic profile as for parental pre-pregnancy BMI associations but with greater magnitudes. Adjustment of parental BMI-offspring metabolic traits associations for offspring BMI suggested the parental associations were largely due to the association of parental BMI with offspring BMI. Limitations of this study are that inferences cannot be drawn about the role of circulating maternal fetal fuels (i.e., glucose, lipids, fatty acids, and amino acids) on later offspring metabolic profile. In addition, BMI may not reflect potential effects of maternal pregnancy fat distribution.

CONCLUSION

Our findings suggest that maternal BMI-offspring metabolome associations are likely to be largely due to shared genetic or familial lifestyle confounding rather than to intrauterine mechanisms.

A Reappraisal of Testosterone's Binding in Circulation: Physiological and Clinical Implications

In the circulation, testosterone and other sex hormones are bound to binding proteins, which play an important role in regulating their transport, distribution, metabolism, and biological activity. According to the free hormone hypothesis, which has been debated extensively, only the unbound or free fraction is biologically active in target tissues. Consequently, accurate determination of the partitioning of testosterone between bound and free fractions is central to our understanding of how its delivery to the target tissues and biological activity are regulated and consequently to the diagnosis and treatment of androgen disorders in men and women. Here, we present a historical perspective on the evolution of our understanding of the binding of testosterone to circulating binding proteins. On the basis of an appraisal of the literature as well as experimental data, we show that the assumptions of stoichiometry, binding dynamics, and the affinity of the prevailing models of testosterone binding to sex hormone-binding globulin and human serum albumin are not supported by published experimental data and are most likely inaccurate. This review offers some guiding principles for the application of free testosterone measurements in the diagnosis and treatment of patients with androgen disorders. The growing number of testosterone prescriptions and widely recognized problems with the direct measurement as well as the computation of free testosterone concentrations render this critical review timely and clinically relevant.

Inverse Relationship between Hepatic Steatosis and Alanine Aminotransferase with Sex Hormone-Binding Globulin in Men

PURPOSE

Sex hormone-binding globulin (SHBG) is a serum glycoprotein produced predominantly in hepatocytes. As such, the synthesis of SHBG could be associated with liver function and metabolic syndrome. Alanine aminotransferase (ALT) levels could reflect hepatocellular injury and insulin resistance; however, the relationship between hepatic steatosis and ALT with SHBG has not been investigated in humans. The objective of this study was to investigate the associations between SHBG and hepatocyte damage among Korean male patients with hepatic steatosis enrolled in a health examination program.

MATERIALS AND METHODS

We performed a retrospective cross-sectional study with 922 participants who underwent routine health examinations. A total of 922 men with or without hepatic steatosis were divided into three groups. We analyzed the risk of lower serum SHBG levels with or without elevated serum ALT levels using odds ratios with 95% confidence intervals (CIs).

RESULTS

A significantly increased risk of lower serum SHBG level was observed in the group with hepatic steatosis and ALT elevation (95% CI 1.591-4.681).

CONCLUSION

In men with hepatic steatosis, we found that elevated serum ALT levels were associated with lower serum SHBG levels. This finding suggests that subjects with both hepatic steatosis and increased ALT should be considered to have low levels of SHBG.

Lower SHBG level is associated with higher leptin and lower adiponectin levels as well as metabolic syndrome, independent of testosterone

In addition to testosterone (T), the emerging role of sex hormone-binding globulin (SHBG) in pathogenesis of metabolic syndrome (MetS) has been noted recently. However, reports of associations with serum adipocytokine levels are still limited. Therefore, we conducted this study to evaluate whether serum T and SHBG levels are independent predictors for the risk of MetS that are associated with adiponectin and leptin levels in 614 Taiwanese men over 40 years old collected from a free health screening. Subjects in the lowest quartile of TT and SHBG levels are exposed to a 1.58 and 3.22 times risk of developing MetS, as compared to those in the highest quartile of TT and SHBG levels. However, SHBG retains its significance independent of TT as a MetS risk predictor, but not vice versa. In addition, SHBG was significantly correlated with both adiponectin and leptin levels even after adjusting for TT levels. In conclusion, SHBG served as a major predictor for the risk of MetS and was correlated with serum adiponectin and leptin levels that are independent of T. Further studies are needed to elucidate the true role of SHBG in the pathogenesis of MetS and possible mechanisms associated with serum adiponectin and leptin levels.

Follicle stimulating hormone, its novel association with sex hormone binding globulin in men and postmenopausal women

PURPOSE

Follicle stimulating hormone plays direct roles in a variety of nongonadal tissues and sex hormone binding globulin is becoming the convergence of the crosstalk among metabolic diseases. However, no studies have explored the association between follicle stimulating hormone and sex hormone binding globulin. We aimed to study this association among men and women.

METHODS

SPECT-China is a population-based study conducted since 2014. This study included 4206 men and 2842 postmenopausal women. Collected serum was assayed for gonadotropins, sex hormone binding globulin, sex hormones etc. Regression analyses were performed to assess the relationship between sex hormone binding globulin and follicle stimulating hormone and other variables including metabolic factors, thyroid function and sex hormones. Treatment with follicle stimulating hormone at different concentrations of 0, 5, 50 and 100 IU/L for 24 h was performed in HepG2 cells.

RESULTS

In Spearman correlation, sex hormone binding globulin was significantly correlated with FSH, triglycerides, thyroxins, body mass index and blood pressure in men and postmenopausal women (all P < 0.05). In regression analyses, follicle stimulating hormone was a significant predictor of sex hormone binding globulin in men and postmenopausal women (P < 0.05), independent of above variables. Follicle stimulating hormone induced sex hormone binding globulin expression in a dose-dependent fashion in HepG2 cells.

CONCLUSION

Serum follicle stimulating hormone levels were positively associated with circulating sex hormone binding globulin levels in men and postmenopausal women. This association is independent of age, insulin resistance, hepatic function, lipid profile, thyroid function, adiposity, blood pressure, and endogenous sex hormones.

The biomarker and causal roles of homoarginine in the development of cardiometabolic diseases: an observational and Mendelian randomization analysis

High L-homoarginine (hArg) levels are directly associated with several risk factors for cardiometabolic diseases whereas low levels predict increased mortality in prospective studies. The biomarker role of hArg in young adults remains unknown. To study the predictive value of hArg in the development of cardiometabolic risk factors and diseases, we utilized data on high-pressure liquid chromatography-measured hArg, cardiovascular risk factors, ultrasound markers of preclinical atherosclerosis and type 2 diabetes from the population-based Young Finns Study involving 2,106 young adults (54.6% females, aged 24–39). We used a Mendelian randomization approach involving tens to hundreds of thousands of individuals to test causal associations. In our 10-year follow-up analysis, hArg served as an independent predictor for future hyperglycaemia (OR 1.31, 95% CI 1.06–1.63) and abdominal obesity (OR 1.60, 95% 1.14–2.30) in men and type 2 diabetes in women (OR 1.55, 95% CI 1.02–2.41). The MR analysis revealed no evidence of causal associations between serum hArg and any of the studied cardiometabolic outcomes. In conclusion, lifetime exposure to higher levels of circulating hArg does not seem to alter cardiometabolic disease risk. Whether hArg could be used as a biomarker for identification of individuals at risk developing cardiometabolic abnormalities merits further investigation.

Associations of Steroid Sex Hormones and Sex Hormone-Binding Globulin With the Risk of Type 2 Diabetes in Women: A Population-Based Cohort Study and Meta-analysis

It remains unclear whether endogenous sex hormones (ESH) are associated with risk of type 2 diabetes (T2D) in women. Data of 3,117 postmenopausal women participants of the Rotterdam Study were analyzed to examine whether ESH and sex hormone-binding globulin (SHBG) were associated with the risk of incident T2D. Additionally, we performed a systematic review and meta-analysis of studies assessing the prospective association of ESH and SHBG with T2D in women. During a median follow-up of 11.1 years, we identified 384 incident cases of T2D in the Rotterdam Study. No association was observed between total testosterone (TT) or bioavailable testosterone (BT) with T2D. SHBG was inversely associated with the risk of T2D, whereas total estradiol (TE) was associated with increased risk of T2D. Similarly, in the meta-analysis of 13 population-based prospective studies involving more than 1,912 incident T2D cases, low levels of SHBG and high levels of TE were associated with increased risk of T2D, whereas no associations were found for other hormones. The association of SHBG with T2D did not change by menopause status, whereas the associations of ESH and T2D were based only in postmenopausal women. SHBG and TE are independent risk factors for the development of T2D in women.

Normo- and hyperandrogenic women with polycystic ovary syndrome exhibit an adverse metabolic profile through life

OBJECTIVE

To compare the metabolic profiles of normo- and hyperandrogenic women with polycystic ovary syndrome (PCOS) with those of control women at different ages during reproductive life.

DESIGN

Case-control study.

SETTING

Not applicable.

PATIENT(S)

In all, 1,550 women with normoandrogenic (n = 686) or hyperandrogenic (n = 842) PCOS and 447 control women were divided into three age groups: <30, 30-39, and >39 years).

INTERVENTIONS(S)

None.

MAIN OUTCOME MEASURE(S)

Body mass index (BMI), waist circumference, blood pressure, glucose, insulin, cholesterol, lipoproteins, triglycerides and high-sensitivity C-reactive protein.

RESULT(S)

Both normo- and hyperandrogenic women with PCOS were more obese, especially abdominally. They had increased serum levels of insulin (fasting and in oral glucose tolerance tests), triglycerides, low-density lipoprotein, and total cholesterol, higher blood pressure, and lower high-density lipoprotein levels independently from BMI compared with the control population as early as from young adulthood until menopause. The prevalence of metabolic syndrome was two- to fivefold higher in women with PCOS compared with control women, depending on age and phenotype, and the highest prevalence was observed in hyperandrogenic women with PCOS at late reproductive age.

CONCLUSION(S)

When evaluating metabolic risks in women with PCOS, androgenic status, especially abdominal obesity and age, should be taken into account, which would allow tailored management of the syndrome from early adulthood on.

Testosterone: Relationships with Metabolic Disorders in Men-An Observational Study from SPECT-China

BACKGROUND

The strength of associations between total testosterone (TT) and metabolic parameters may vary in different nature of population structure; however, no study has ever given this information in Chinese population, especially those without metabolic syndrome (MS). We aimed to analyze the association magnitudes between TT and multiple metabolic parameters in general Chinese men.

METHODS

4309 men were recruited from SPECT-China study in 2014-2015, which was performed in 22 sites in East China. TT, weight status, and various metabolic parameters were measured. Linear and logistic regressions were used to analyze the associations.

RESULTS

Men in lower TT quartiles had worse metabolic parameters including body mass index, triglycerides, HbA1c, and HOMA-IR (all P for trend < 0.001). Body mass index (B -0.32, 95%CI -0.35 to -0.29) and obesity (OR 0.40, 95%CI 0.35-0.45) had the largest association magnitude per one SD increment in TT, while blood pressure and hypertension (OR 0.90, 95%CI 0.84-0.98) had the smallest. These associations also persisted in individuals without metabolic syndrome.

CONCLUSIONS

Obesity indices had closer relationships with TT than most other metabolic measures with blood pressure the least close. These associations remained robust after adjustment for adiposity and in subjects without metabolic syndrome.

Metabolic profiling of pregnancy: cross-sectional and longitudinal evidence

BACKGROUND

Pregnancy triggers well-known alterations in maternal glucose and lipid balance but its overall effects on systemic metabolism remain incompletely understood.

METHODS

Detailed molecular profiles (87 metabolic measures and 37 cytokines) were measured for up to 4260 women (24-49 years, 322 pregnant) from three population-based cohorts in Finland. Circulating molecular concentrations in pregnant women were compared to those in non-pregnant women. Metabolic profiles were also reassessed for 583 women 6 years later to uncover the longitudinal metabolic changes in response to change in the pregnancy status.

RESULTS

Compared to non-pregnant women, all lipoprotein subclasses and lipids were markedly increased in pregnant women. The most pronounced differences were observed for the intermediate-density, low-density and high-density lipoprotein triglyceride concentrations. Large differences were also seen for many fatty acids and amino acids. Pregnant women also had higher concentrations of low-grade inflammatory marker glycoprotein acetyls, higher concentrations of interleukin-18 and lower concentrations of interleukin-12p70. The changes in metabolic concentrations for women who were not pregnant at baseline but pregnant 6 years later (or vice versa) matched (or were mirror-images of) the cross-sectional association pattern. Cross-sectional results were consistent across the three cohorts and similar longitudinal changes were seen for 653 women in 4-year and 497 women in 10-year follow-up. For multiple metabolic measures, the changes increased in magnitude across the three trimesters.

CONCLUSIONS

Pregnancy initiates substantial metabolic and inflammatory changes in the mothers. Comprehensive characterisation of normal pregnancy is important for gaining understanding of the key nutrients for fetal growth and development. These findings also provide a valuable molecular reference in relation to studies of adverse pregnancy outcomes.

Effects of hormonal contraception on systemic metabolism: cross-sectional and longitudinal evidence

Background: Hormonal contraception is commonly used worldwide, but its systemic effects across lipoprotein subclasses, fatty acids, circulating metabolites and cytokines remain poorly understood.

Methods: A comprehensive molecular profile (75 metabolic measures and 37 cytokines) was measured for up to 5841 women (age range 24–49 years) from three population-based cohorts. Women using combined oral contraceptive pills (COCPs) or progestin-only contraceptives (POCs) were compared with those who did not use hormonal contraception. Metabolomics profiles were reassessed for 869 women after 6 years to uncover the metabolic effects of starting, stopping and persistently using hormonal contraception.

Results: The comprehensive molecular profiling allowed multiple new findings on the metabolic associations with the use of COCPs. They were positively associated with lipoprotein subclasses, including all high-density lipoprotein (HDL) subclasses. The associations with fatty acids and amino acids were strong and variable in direction. COCP use was negatively associated with albumin and positively associated with creatinine and inflammatory markers, including glycoprotein acetyls and several growth factors and interleukins. Our findings also confirmed previous results e.g. for increased circulating triglycerides and HDL cholesterol. Starting COCPs caused similar metabolic changes to those observed cross-sectionally: the changes were maintained in consistent users and normalized in those who stopped using. In contrast, POCs were only weakly associated with metabolic and inflammatory markers. Results were consistent across all cohorts and for different COCP preparations and different types of POC delivery.

Conclusions: Use of COCPs causes widespread metabolic and inflammatory effects. However, persistent use does not appear to accumulate the effects over time and the metabolic perturbations are reversed upon discontinuation. POCs have little effect on systemic metabolism and inflammation.

Sex Hormone-Binding Globulin in Children and Adolescents

Sex hormone-binding globulin (SHBG) is a circulating glycoprotein that transports testosterone and other steroids in the blood. Interest in SHBG has escalated in recent years because of its inverse association with obesity and insulin resistance, and because many studies have linked lower circulating levels of SHBG to metabolic syndrome, type 2 diabetes, nonalcoholic fatty liver disease, polycystic ovary syndrome, and early puberty. The purpose of this review is to summarize molecular, clinical, endocrine, and epidemiological findings to illustrate how measurement of plasma SHBG may be useful in clinical medicine in children.