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

Association of dietary nutrient intake with type 2 diabetes: A Mendelian randomization study

Observational research suggests that the evidence linking dietary nutrient intake (encompassing minerals, vitamins, amino acids, and unsaturated fatty acids) to type 2 diabetes (T2D) is both inconsistent and limited. This study aims to explore the potential causal relationship between dietary nutrients and T2D. Causal estimation utilized Mendelian randomization techniques. Single nucleotide polymorphisms linked to dietary nutrients were identified from existing genome-wide association studies and used as instrumental variables. Genome-wide association studies data pertinent to T2D were sourced from the DIMANTE consortium and the FinnGen database. Techniques including inverse variance weighting (IVW), weighted mode, weighted median, and Mendelian randomization-Egger were employed for causal inference, complemented by sensitivity analysis. Genetically predicted higher phenylalanine (IVW: odds ratio = 1.10 95% confidence interval 1.04-1.17, P = 1.5 × 10-3, q_pval = 3.4 × 10-2) and dihomo-gamma-linolenic acid (IVW: odds ratio = 1.001 95% confidence interval 1.0006-1.003, P = 3.7 × 10-3, q_pval = 4.1 × 10-2) levels were directly associated with T2D risk. Conversely, no causal relationships between other nutrients and T2D were established. We hypothesize that phenylalanine and dihomo-gamma-linolenic acid contribute to the pathogenesis of T2D. Clinically, the use of foods with high phenylalanine content may pose potential risks for patients with a heightened risk of T2D. Our study provides evidence supporting a causal link between dietary nutrient intake and the development of T2D.

Maternal metabolic profiling across body mass index groups: An exploratory longitudinal study

INTRODUCTION

Increased BMI has been identified as a risk factor for most pregnancy complications, but the underlying metabolic factors mediating the detrimental effects of BMI are largely unknown. We aimed to compare metabolic profiles in overweight/obese women (body mass index [BMI] ≥ 25 kg/m2 ) and normal weight/underweight women (BMI < 25 kg/m2 ) across gestation. We also explored how gestational weight gain (GWG) affected maternal metabolic profiles.

MATERIAL AND METHODS

Exploratory nested case-control study based on a prospective longitudinal cohort of women who were healthy prior to pregnancy and gave birth at Oslo University Hospital from 2002 to 2008. The sample consisted of 48 women who were overweight/obese and 59 normal-weight/underweight women. Plasma samples from four time points in pregnancy (weeks 14-16, 22-24, 30-32 and 36-38) were analyzed by nuclear magnetic resonance spectroscopy and 91 metabolites were measured. Linear regression models were fitted for each of the metabolites at each time point.

RESULTS

Overweight or obese women had higher levels of lipids in very-low-density lipoprotein (VLDL), total triglycerides, triglycerides in VLDL, total fatty acids, monounsaturated fatty acids, saturated fatty acids, leucine, valine, and total branched-chain amino acids in pregnancy weeks 14-16 compared to underweight and normal-weight women. Docosahexaenoic acid and degree of unsaturation were significantly lower in overweight/obese women in pregnancy weeks 36-38. In addition, overweight or obese women had higher particle concentration of XXL-VLDL and glycoprotein acetyls (GlycA) at weeks 14-16 and 30-32. GWG did not seem to affect the metabolic profile, regardless of BMI group when BMI was treated as a dichotomous variable, ≥25 kg/m2 (yes/no).

CONCLUSIONS

Overweight or obese women had smaller pregnancy-related metabolic alterations than normal-weight/underweight women. There was a trend toward higher triglyceride and VLDL particle concentration in overweight/obese women. As this was a hypothesis-generating study, the similarities with late-onset pre-eclampsia warrant further investigation. The unfavorable development of fatty acid composition in overweight/obese women, with possible implication for the offspring, should also be studied further in the future.

Low levels of sex hormone-binding globulin predict an increased breast cancer risk and its underlying molecular mechanisms

Sex hormone-binding globulin (SHBG) is a serum glycoprotein exhibiting the unique feature of binding sex steroids with high affinity and specificity. Over the past few decades, there have been significant breakthroughs in our understanding of the function and regulation of SHBG. The biological role of SHBG has expanded from being considered a simple sex hormone transporter to being associated with several complex physiological and pathological changes in a variety of target tissues. Many factors can affect the plasma SHBG levels, with fluctuations in circulating levels affecting the development of various diseases, such as increasing the risk of developing breast cancer. This article reviews the clinical significance of changes in circulating SHBG levels in the development of breast cancer and the possible influence of these levels on endocrine drug resistance in hormone receptor-positive breast cancer. Higher levels of plasma SHBG significantly reduce the risk of estrogen receptor-positive breast cancer, especially in postmenopausal women. Moreover, the molecular mechanisms by which SHBG affects breast cancer risk are also summarized in detail. Finally, transcriptomics and proteomics data revealed that SHBG expression in breast tissue can effectively distinguish breast cancer from normal tissue. Additionally, the association between SHBG expression levels and various classical tumor-related pathways was investigated.

Association of iron homeostasis biomarkers in type 2 diabetes and glycaemic traits: a bidirectional two-sample Mendelian randomization study

BACKGROUND

Mendelian randomization (MR) studies show iron positively associated with type 2 diabetes (T2D) but included potentially biasing hereditary haemochromatosis variants and did not assess reverse causality.

METHODS

We assessed the relation of iron homeostasis with T2D and glycaemic traits bidirectionally, using genome-wide association studies (GWAS) of iron homeostasis biomarkers [ferritin, serum iron, total iron-binding capacity (TIBC), transferrin saturation (TSAT) (n ≤ 246 139)], T2D (DIAMANTE n = 933 970 and FinnGen n = 300 483), and glycaemic traits [fasting glucose (FG), 2-h glucose, glycated haemoglobin (HbA1c) and fasting insulin (FI) (n ≤ 209 605)]. Inverse variance weighting (IVW) was the main analysis, supplemented with sensitivity analyses and assessment of mediation by hepcidin.

RESULTS

Iron homeostasis biomarkers were largely unrelated to T2D, although serum iron was potentially associated with higher T2D [odds ratio: 1.07 per standard deviation; 95% confidence interval (CI): 0.99 to 1.16; P-value: 0.078) in DIAMANTE only. Higher ferritin, serum iron, TSAT and lower TIBC likely decreased HbA1c, but were not associated with other glycaemic traits. Liability to T2D likely increased TIBC (0.03 per log odds; 95% CI: 0.01 to 0.05; P-value: 0.005), FI likely increased ferritin (0.29 per log pmol/L; 95% CI: 0.12 to 0.47; P-value: 8.72 x 10-4). FG likely increased serum iron (0.06 per mmol/L; 95% CI: 0.001 to 0.12; P-value: 0.046). Hepcidin did not mediate these associations.

CONCLUSION

It is unlikely that ferritin, TSAT and TIBC cause T2D although an association for serum iron could not be excluded. Glycaemic traits and liability to T2D may affect iron homeostasis, but mediation by hepcidin is unlikely. Corresponding mechanistic studies are warranted.

Sex hormone-binding globulin improves lipid metabolism and reduces inflammation in subcutaneous adipose tissue of metabolic syndrome-affected horses

Equine metabolic syndrome (EMS) is a steadily growing endocrine disorder representing a real challenge in veterinary practice. As a multifactorial condition, EMS is characterized by three main metabolic abnormalities including insulin resistance, increased adiposity or obesity and hoof laminitis. Adipose tissue dysfunction is recognized as a core pathophysiological determinant of EMS, as it strongly participates to lipotoxicity and systemic metaflammation, both of which have been closely linked to the development of generalized insulin resistance. Besides, sex hormone binding globulin (SHBG) is an important sex steroids transporters that has been recently proposed as an important metabolic mediator. Therefore, the aim of this study was to verify whether SHBG treatment may ameliorate subcutaneous adipose tissue metabolic failure under EMS condition in terms of lipidome homeostasis, lipid metabolism programs, insulin signalling and local inflammation. Subcutaneous adipose tissue (SAT) biopsies were collected post-mortem from healthy (n = 3) and EMS (n = 3) slaughtered horses. SHBG protein has been applied to SAT samples from EMS horses for 24 h at a final concentration of 50 nM, while control groups (healthy and untreated EMS) were cultured in the presence of SHBG-vehicle only. Tissues from all groups were afterwards secured for downstream analysis of gene expression using RT-qPCR, protein levels by Western blot and ELISA assay and lipidomics through GC-MS technique. Obtained results showcased that SHBG intervention efficiently normalized the altered fatty acids (FAs) profiles by lowering the accumulation of saturated and trans FAs, as well as the pro-inflammatory arachidonic and linoleic acids. Moreover, SHBG showed promising value for the regulation of adipocyte lipolysis and engorgement by lowering the levels of perilipin-1. SHBG exerted moderated effect toward SCD1 and FASN enzymes expression, but increased the LPL abundance. Interestingly, SHBG exhibited a negative regulatory effect on pro-adipogenic stimulators and induced higher expression of KLF3, IRF3 and β-catenin, known as strong adipogenesis repressors. Finally, SHBG protein showed remarkable ability in restoring the insulin signal transduction, IR/IRS/Pi3K/AKT phosphorylation events and GLUT4 transporter abundance, and further attenuate pro-inflammatory response by lowering IL-6 tissue levels and targeting the PDIA3/ERK axis. Overall, the obtained data clearly demonstrate the benefice of SHBG treatment in the regulation of adipose tissue metabolism in the course of EMS and provide new insights for the development of molecular therapies with potential translational application to human metabolic disorders.

Circulating sex hormone-binding globulin levels and ischemic stroke risk: a Mendelian randomization study

PURPOSE

Previous studies have presented conflicting findings regarding the protective effects of circulating sex hormone-binding globulin (SHBG) on ischemic stroke (IS). This study aimed to assess the causal effect of SHBG on IS using Mendelian randomization (MR) analysis and to identify potential mediators.

METHODS

First, the causal effect of SHBG on any IS (AIS), cardioembolic stroke (CES), large artery stroke (LAS), and small vessel stroke (SVS) was assessed by inverse variance weighed (IVW) method. Two additional MR methods (weighted median and MR-Egger) were used to supplement the IVW results. Subsequently, a two-step MR was further performed to assess whether three glycemic profiles [fasting glucose, fasting insulin, and glycated hemoglobin (HbA1c)] and five lipid profiles (high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, non-HDL cholesterol, total cholesterol, and triglycerides) mediated the causal effect. Furthermore, Cochrane's Q test, MR-Egger intercept test, MR-PRESSO global test, and leave-one-out analysis were performed for sensitivity analyses.

RESULTS

The IVW results showed that SHBG significantly reduced SVS risk (odds ratio= 0.60, 95% confidence interval: 0.47-0.77, P = 4.60E-05). The weighted median and MR-Egger results were parallel to IVW. However, no significant associations were found between SHBG and AIS, CES, and LAS. Mediation analysis indicated that HbA1c may be involved in SHBG reducing SVS risk. Sensitivity tests demonstrated the reliability of causal estimates.

CONCLUSIONS

Circulating SHBG levels may decrease SVS risk by lowering HbA1c levels. Therefore, individuals with low circulating SHBG levels should focus on glycemic control to reduce future SVS risk.

Sleep-related factors and circulating levels of sex hormones in premenopausal Japanese women

Sleep disruption and circadian disruption have been proposed to be risk factors of breast cancer. The present study examined the associations of sleep-related factors, referring to night shift work, sleep habits, and sleep disturbances, with the plasma levels of sex hormones in premenopausal Japanese women. Study participants were 432 women who had regular menstrual cycles less than 40 days long. Information on their history of night shift work and sleep disturbances was obtained using a self-administered questionnaire. Information on their sleep habits, such as usual wake-up times, bedtimes, and ambient light level while sleeping, was obtained in an interview. The participants' height and weight were measured. Plasma concentrations of estradiol, testosterone, dehydroepiandrosterone sulfate, sex hormone-binding globulin (SHBG), FSH, and LH were also measured. After controlling for the phase of the menstrual cycle and other covariates, more years of night shift work ≥ once a week during the past 10 years was significantly associated with a lower SHBG and a higher free estradiol level. Shorter sleep duration was significantly associated with the higher total, bioavailable, and free testosterone levels. Sleep disturbance by awaking after sleep onset was significantly associated with a high free estradiol level. The data suggest that long-term night shift work, short sleep duration, and arousal during sleep are associated with higher estradiol or testosterone levels in premenopausal women.

Genetic analyses implicate complex links between adult testosterone levels and health and disease

BACKGROUND

Testosterone levels are linked with diverse characteristics of human health, yet, whether these associations reflect correlation or causation remains debated. Here, we provide a broad perspective on the role of genetically determined testosterone on complex diseases in both sexes.

METHODS

Leveraging genetic and health registry data from the UK Biobank and FinnGen (total N = 625,650), we constructed polygenic scores (PGS) for total testosterone, sex-hormone binding globulin (SHBG) and free testosterone, associating these with 36 endpoints across different disease categories in the FinnGen. These analyses were combined with Mendelian Randomization (MR) and cross-sex PGS analyses to address causality.

RESULTS

We show testosterone and SHBG levels are intricately tied to metabolic health, but report lack of causality behind most associations, including type 2 diabetes (T2D). Across other disease domains, including 13 behavioral and neurological diseases, we similarly find little evidence for a substantial contribution from normal variation in testosterone levels. We nonetheless find genetically predicted testosterone affects many sex-specific traits, with a pronounced impact on female reproductive health, including causal contribution to PCOS-related traits like hirsutism and post-menopausal bleeding (PMB). We also illustrate how testosterone levels associate with antagonistic effects on stroke risk and reproductive endpoints between the sexes.

CONCLUSIONS

Overall, these findings provide insight into how genetically determined testosterone correlates with several health parameters in both sexes. Yet the lack of evidence for a causal contribution to most traits beyond sex-specific health underscores the complexity of the mechanisms linking testosterone levels to disease risk and sex differences.

Genetically predicted sex hormone levels and health outcomes: phenome-wide Mendelian randomization investigation

BACKGROUND

Sex hormone-binding globulin (SHBG), testosterone and oestradiol have been associated with many diseases in observational studies; however, the causality of associations remains unestablished.

METHODS

A phenome-wide Mendelian randomization (MR) association study was performed to explore disease outcomes associated with genetically proxied circulating SHBG, testosterone and oestradiol levels by using updated genetic instruments in 339 197 unrelated White British individuals (54% female) in the UK Biobank. Two-sample MR analyses with data from large genetic studies were conducted to replicate identified associations in phenome-wide MR analyses. Multivariable MR analyses were performed to investigate mediation effects of hormone-related biomarkers in observed associations with diseases.

RESULTS

Phenome-wide MR analyses examined associations of genetically predicted SHBG, testosterone and oestradiol levels with 1211 disease outcomes, and identified 28 and 13 distinct phenotypes associated with genetically predicted SHBG and testosterone, respectively; 22 out of 28 associations for SHBG and 10 out of 13 associations for testosterone were replicated in two-sample MR analyses. Higher genetically predicted SHBG levels were associated with a reduced risk of hypertension, type 2 diabetes, diabetic complications, coronary atherosclerotic outcomes, gout and benign and malignant neoplasm of uterus, but an increased risk of varicose veins and fracture (mainly in females). Higher genetically predicted testosterone levels were associated with a lower risk of type 2 diabetes, coronary atherosclerotic outcomes, gout and coeliac disease mainly in males, but an increased risk of cholelithiasis in females.

CONCLUSIONS

These findings suggest that sex hormones may causally affect risk of several health outcomes.

The emerging roles of PHOSPHO1 and its regulated phospholipid homeostasis in metabolic disorders

Emerging evidence suggests that phosphoethanolamine/phosphocholine phosphatase 1 (PHOSPHO1), a specific phosphoethanolamine and phosphocholine phosphatase, is involved in energy metabolism. In this review, we describe the structure and regulation of PHOSPHO1, as well as current knowledge about the role of PHOSPHO1 and its related phospholipid metabolites in regulating energy metabolism. We also examine mechanistic evidence of PHOSPHO1- and phospholipid-mediated regulation of mitochondrial and lipid droplets functions in the context of metabolic homeostasis, which could be potentially targeted for treating metabolic disorders.

The relationships between FLAIS, a novel insulin sensitivity index, and cardiovascular risk factors in a population-based study

Background

Insulin resistance is a risk factor for cardiovascular disease. Recently, we have developed a novel index, FLAIS (Fasting Laboratory Assessment of Insulin Sensitivity), which accurately reflects insulin sensitivity, measured with hyperinsulinemic-euglycemic clamp, in different groups of subjects. The aim of the present study was to assess the relationship of FLAIS with cardiovascular risk factors in a population-based study.

Methods

The study group comprised 339 individuals from the ongoing Białystok Plus study, without previously known diabetes. Clinical examination, oral glucose tolerance test and the measurement of blood laboratory parameters were performed.

Results

Prediabetes (impaired fasting glucose and/or impaired glucose tolerance) was diagnosed in 165 individuals whereas type 2 diabetes was diagnosed in 19 subjects. FLAIS was lower in individuals with prediabetes and diabetes in comparison with individuals with normal glucose tolerance. FLAIS was significantly related to waist circumference, systolic and diastolic blood pressure, triglycerides, HDL-cholesterol and LDL-cholesterol in the entire study group and in the subgroups with normal glucose tolerance and with prediabetes/diabetes. HOMA-IR, QUICKI and Matsuda index were not related to blood pressure and LDL-cholesterol in individuals with normal glucose tolerance. Majority of the adjusted models with FLAIS were characterized by better fit with the data in comparison with other indices for all cardiovascular risk factors except waist circumference.

Conclusions

FLAIS represents useful index to assess the cluster of insulin resistance-associated cardiovascular risk factors in general population.

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.

Associations of endogenous androgens and sex hormone-binding globulin with kidney function and chronic kidney disease

INTRODUCTION

The role of endogenous androgens in kidney function and disease has not been extensively explored in men and women.

RESEARCH DESIGN AND METHODS

We analyzed data from the observational KORA F4 study and its follow-up examination KORA FF4 (median follow-up time 6.5 years) including 1293 men and 650 peri- and postmenopausal women, not using exogenous sex hormones. We examined the associations between endogenous androgens (testosterone [T], dihydrotestosterone [DHT], free T [fT], free DHT [fDHT], and T/DHT), with estimated glomerular filtration rate (eGFR) at baseline and follow-up, prevalent, and incident chronic kidney disease (CKD) adjusting for common CKD risk factors.

RESULTS

At baseline, 73 men (5.7%) and 54 women (8.4%) had prevalent CKD. Cross-sectionally, no significant associations between androgens and kidney function were observed among men. In women, elevated T (β=-1.305, [95% CI -2.290; -0.320]) and fT (β=-1.423, [95% CI -2.449; -0.397]) were associated with lower eGFR. Prospectively, 81 men (8.8%) and 60 women (15.2%) developed incident CKD. In women, a reverse J-shaped associations was observed between DHT and incident CKD (P_non-linear=0.029), while higher fDHT was associated with lower incident CKD risk (odds ratio per 1 standard deviation=0.613, [95% CI 0.369; 0.971]. Among men, T/DHT (β=-0.819, [95% CI -1.413; -0.226]) and SHBG (P_non-linear=0.011) were associated with eGFR at follow-up but not with incident CKD. Some associations appeared to be modified by type 2 diabetes (T2D).

CONCLUSION

Suggestive associations are observed of androgens and SHBG with kidney impairment among men and women. However, larger well-phenotyped prospective studies are required to further elucidate the potential of androgens, SHBG, and T2D as modifiable risk factors for kidney function and CKD.

Prevalence, Pattern and Predictors for Dyslipidemia of Chinese Women With Polycystic Ovary Syndrome

Objective: To investigate the prevalence, pattern and risk predictors for dyslipidemia among Chinese women with polycystic ovary syndrome (PCOS). Study Design and Methods: A total of 1,000 women diagnosed as PCOS by modified Rotterdam criteria were enrolled in 27 hospitals across China in a randomized controlled trial. Anthropometric, metabolic parameters, sex hormone, and lipid levels were measured at the baseline visit. Dyslipidemia was defined according to total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG) level. Independent t-test and logistic regression were used to identify predictors for dyslipidemia. Area under the receiver operating characteristic curve (AUC) was calculated. Results: A total of 41.3% of the women had dyslipidemia, and the prevalence of abnormal TC, LDL-C, HDL-C, and TG were 8.6, 9.1, 26.9, and 17.5%, respectively. Logistic regression found that age, waist circumference, insulin, follicle-stimulating hormone, and sex hormone-binding globulin were independent predictors for dyslipidemia. When combining these predictors, the AUC was 0.744. The cut-off points were age >28.5 years, waist circumference >86.5 cm, insulin >96.0 pmol/L, follicle-stimulating hormone <5.6 mIU/mL, and sex hormone-binding hormone <31.0 nmol/L, respectively. Conclusion: Dyslipidemia was common in Chinese women with PCOS, and low HDL-C level was the predominant lipid abnormality. Age, waist circumference, follicle-stimulating hormone, insulin and sex hormone-binding globulin were predictive for dyslipidemia among Chinese women with PCOS.

Overfeeding-induced weight gain elicits decreases in sex hormone-binding globulin in healthy males-Implications for body fat distribution

OBJECTIVE

Obesity and upper-body fat elevates cardiometabolic risk. However, mechanisms predisposing to upper-body fat accumulation are not completely understood. In males, low testosterone (T) frequently associates with obesity, and estrogen deficiency may contribute to upper-body adiposity. This study examines the effects of overfeeding-induced weight gain on changes in gonadal hormones in healthy males and its association with regional fat depots.

METHODS

Twenty-five males (age: 29.7 ± 6.9 years; BMI: 24.7 ± 3.1 kg/m2 ) were overfed for 8 weeks to gain approximately 5% body weight. Changes in total and regional fat depots were assessed using dual-energy x-ray absorptiometry and abdominal computed tomography scans. Circulating T, estrone (E1), 17-β estradiol (E2), and sex hormone-binding globulin (SHBG) concentrations were measured at baseline and after weight gain.

RESULTS

Overfeeding resulted in 3.8 (3.3, 4.9) kg weight gain with increased total body fat. Weight gain did not alter circulating T (p = 0.82), E1 (p = 0.52), or E2 (p = 0.28). However, SHBG decreased (p = 0.04) along with consequent increases in T/SHBG (p = 0.02) and E2/SHBG (p = 0.03) ratios. Importantly, baseline E2/SHBG ratio was inversely associated with increases in upper-body fat mass (ρ = -0.43, p = 0.03).

CONCLUSIONS

Modest weight gain does not alter circulating gonadal hormones in males but may increase bioavailability of T and E2 via decreases in SHBG. The association between baseline E2/SHBG and regional fat mass suggests that higher levels of bioavailable E2 may protect from upper-body fat accumulation during overfeeding-induced modest weight gain in healthy males. Our study suggests a complex relationship between adipose tissue, gonadal hormones, and fat accumulation in males.

Genetically predicted sex hormone binding globulin and ischemic heart disease in men and women: a univariable and multivariable Mendelian randomization study

Men are more vulnerable to ischemic heart disease (IHD) than women, possibly due to testosterone. Correspondingly, sex hormone binding globulin (SHBG) which lowers circulating testosterone might protect men against IHD. SHBG may also affect IHD independent of testosterone, which has not previously been examined. To assess the sex-specific role of SHBG in IHD, in univariable Mendelian randomization (MR), we used sex-specific, genome-wide significant genetic variants to predict SHBG, and examined their association with IHD in the UK Biobank. We also replicated using genetic instruments from Japanese men and applied to Biobank Japan. To assess the role of SHGB independent of testosterone in men, we used multivariable MR controlling for testosterone. Genetically predicted SHBG was associated with lower IHD risk in men [odds ratio (OR) 0.78 per standard deviation, 95% confidence interval (CI) 0.70 to 0.87], and the association was less clear in women. The estimates were similar in Japanese. The inverse association remained after controlling for testosterone in men (OR 0.79, 95% CI 0.71 to 0.88). SHBG might lower the risk of IHD in men, with a role independent of testosterone. Exploring intervention strategies that increase SHBG is important for targeting IHD treatments.

Hyperandrogenemia in Early Adulthood Is an Independent Risk Factor for Abnormal Glucose Metabolism in Middle Age

CONTEXT

The role of androgen excess as a contributing factor to abnormal glucose metabolism (AGM) and insulin resistance in women remains controversial.

OBJECTIVE

To investigate whether hyperandrogenemia (HA) estimated by serum testosterone (T) level and free androgen index (FAI) at ages 31 and 46 years is associated with insulin resistance, insulin secretion and AGM by age 46.

DESIGN

Prospective study including 5889 females followed at ages 31 and 46 years.

SETTING

General community.

PARTICIPANTS

Women with HA were compared with normoandrogenic women at ages 31 and 46 years.

INTERVENTION

None.

MAIN OUTCOME MEASUREMENTS

AGM, including prediabetes and type 2 diabetes mellitus, homeostatic model assessments of insulin resistance (HOMA-IR) and of pancreatic β-cell function (HOMA-B).

RESULTS

At age 31 years, HA women displayed increased HOMA-IR (P = 0.002), HOMA-B (P = 0.007), and higher fasting insulin (P = 0.03) than normoandrogenic women after adjusting for body mass index (BMI). At age 46 years, there was a nonsignificant trend toward higher fasting glucose (P = 0.07) and glycated hemoglobin A1 (P = 0.07) levels in HA women. Women in the highest T quartile (odds ratio [OR] = 1.80; 95%CI, 1.15-2.82) at age 31 years and in the 2 highest FAI quartiles at ages 31 (Q4: OR = 3.76; 95% CI, 2.24-6.32) and 46 (Q4: OR = 2.79; 95% CI, 1.74-4.46) years had increased risk for AGM, independently of BMI, when compared with women in Q1. SHBG was inversely associated with AGM (at age 31 years: Q4: OR = 0.37; 95% CI, 0.23-0.60, at age 46 years: Q4: OR = 0.28; 95% CI, 0.17-0.44).

CONCLUSION

Hyperandrogenemia and low SHBG in early and middle age associates with AGM independently of BMI.

Impact of sex hormone-binding globulin on the human phenome

Background: Sex hormone-binding globulin (SHBG) is a circulating glycoprotein and a regulator of sex hormone levels, which has been shown to influence various traits and diseases. The molecular nature of SHBG makes it a feasible target for preventative or therapeutic interventions. A systematic study of its effects across the human phenome may uncover novel associations. Methods: We used a Mendelian randomization phenome-wide association study (MR-pheWAS) approach to systematically appraise the potential functions of SHBG while reducing potential biases such as confounding and reverse causation common to the literature. We searched for potential causal effects of SHBG in UK Biobank (N = 334 977) and followed-up our top findings using two-sample MR analyses to evaluate whether estimates may be biased due to horizontal pleiotropy. Results: Results of the MR-pheWAS across over 21 000 outcome phenotypes identified 12 phenotypes associated with genetically elevated SHBG after Bonferroni correction for multiple testing. Follow-up analysis using two-sample MR indicated the associations of increased natural log SHBG with higher impedance of the arms and whole body, lower pulse rate, lower bone density, higher odds of hip replacement, lower odds of high cholesterol or cholesterol medication use and higher odds of gallbladder removal. Conclusions: Our systematic MR-pheWAS of SHBG, which was comprehensive to the range of phenotypes available in UK Biobank, suggested that higher circulating SHBG affects the body impedance, bone density and cholesterol levels, among others. These phenotypes should be prioritized in future studies aiming to investigate the biological effects of SHBG or develop targets for therapeutic intervention.

The relationships of sex hormone-binding globulin, total testosterone, androstenedione and free testosterone with metabolic and reproductive features of polycystic ovary syndrome

Objective

A recent Mendelian randomization study has suggested a causal role for sex hormone‐binding globulin (SHBG), total testosterone and free testosterone in the pathogenesis of polycystic ovary syndrome (PCOS). The aim of this study was to assess the relationships of SHBG, androstenedione, total and free testosterone with the individual metabolic and reproductive features of PCOS.

Design

Cross‐sectional data in PCOS patients (n=96) prospectively collected in a secondary/tertiary clinic for menstrual cycle disorders.

Methods

Multivariable regression analyses were conducted to study the associations between SHBG, androstenedione, total and free testosterone with metabolic (BMI, waist circumference, systolic and diastolic blood pressure, total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides and homeostatic model assessment for insulin resistance [HOMA2‐IR]) and reproductive features (menstrual cycle length, antral follicle count, anti‐Müllerian hormone, luteinizing hormone, follicle‐stimulating hormone and Ferriman‐Gallwey score) of PCOS.

Results

Serum SHBG and free testosterone, but not total testosterone or androstenedione, were significantly associated with BMI, waist circumference, serum triglycerides, HDL cholesterol, LDL cholesterol and HOMA2‐IR. The strength of the associations with serum lipids was reduced after adjustment for BMI, but not for HOMA2‐IR. Total testosterone was significantly associated with antral follicle count. SHBG, total testosterone and androstenedione were significantly associated with serum AMH. Only the strength of the association for SHBG was reduced after adjustment for BMI.

Conclusions

Serum SHBG is associated with primarily metabolic features, whereas total testosterone and androstenedione are associated with reproductive features of PCOS. These results suggest a differential underlying pathophysiology for the metabolic and reproductive features of PCOS.

Causal effect of sex hormone-binding globulin and testosterone on coronary heart disease: A multivariable and network Mendelian randomization analysis

BACKGROUND

Although observational studies have shown an association between sex hormone-binding globulin (SHBG), testosterone (T) and cardiovascular diseases (CVD), controversy remains. In this study, we aim to explore the causal effects of SHBG and T on Coronary heart disease (CHD).

METHODS

We used univariable, network and multivariable mendelian randomization (MR) analysis to investigate the causal effect of SHBG and T on CHD. We performed inverse variance weighted (IVW) MR as the primary analysis, with the robustness of this approach further tested by other methods in sensitivity analysis. The SHBG and T were collected from the UK Biobank data, about 180,000 men aged 40 to 69 years. CHD was collected from CARDIoGRAMplusC4D 1000 Genomes-based GWAS, which was a meta-analysis including 48 studies and involving 60,801 CHD cases and 123,504 controls.

RESULTS

Using univariable MR-IVW, the results suggested that a one standard deviation (SD) increase in SHBG, the risk of CHD decreased by approximately 14% (OR (95% CI): 0.86(0.76,0.97)), and that a SD increase in total testosterone (TT), the risk also decreased, approximately 8% (OR (95% CI): 0.92(0.85,0.99)). Multivariable MR showed that both SHBG and TT had no direct causal effect with CHD (a SD increase in SHBG: OR (95% CI):0.75(0.57,1.00), P = 0.053; a SD increase in TT: OR (95% CI): 1.05(0.90,1.22), P = 0.53). In the network MR analysis, the results suggested that TT might act as mediator in the causal pathway from SHBG to CHD and account for 93% of the total effect of SHBG on CHD, and that SHBG might be a mediator in the causal pathway from TT to CHD and account for 67% of the total effect of TT on CHD.

CONCLUSIONS

Genetically predicted SHBG and TT were negatively correlated with CHD in both univariable and network MR, which may provide a causal explanation behind the observed conclusion. In addition, TT and SHBG had a bidirectional causal effect. Further work is required to disentangle the downstream effects of SHBG/TT on CHD and the molecular pathways involved, as the simultaneous regulation of SHBG and TT may make it a viable strategy for the prevention or treatment of CHD.

Serum NMR metabolomics uncovers multiple metabolic changes in phenobarbital-treated dogs

INTRODUCTION

Phenobarbital is a commonly used anticonvulsant for the treatment of canine epileptic seizures. In addition to its central nervous system (CNS) depressing effects, long-term phenobarbital administration affects liver function. However, broader metabolic consequences of phenobarbital treatment are poorly characterized.

OBJECTIVES

To identify metabolic changes in the sera of phenobarbital-treated dogs and to investigate the relationship between serum phenobarbital concentration and metabolite levels.

METHODS

Leftovers of clinical samples were used: 58 cases with phenobarbital concentrations ranging from 7.8 µg/mL to 50.8 µg/mL, and 25 controls. The study design was cross-sectional. The samples were analyzed by a canine-specific 1H NMR metabolomics platform. Differences between the case and control groups were evaluated by logistic regression. The linear relationship between metabolite and phenobarbital concentrations was evaluated using linear regression.

RESULTS

Increasing concentrations of glycoprotein acetyls, LDL particle size, palmitic acid, and saturated fatty acids, and decreasing concentrations of albumin, glutamine, histidine, LDL particle concentration, multiple HDL measures, and polyunsaturated fatty acids increased the odds of the sample belonging to the phenobarbital-treated group, having a p-value < .0033, and area under the curve (AUC) > .7. Albumin and glycoprotein acetyls had the best discriminative ability between the groups (AUC: .94). No linear associations between phenobarbital and metabolite concentrations were observed.

CONCLUSION

The identified metabolites are known to associate with, for example, liver and CNS function, inflammatory processes and drug binding. The lack of a linear association to phenobarbital concentration suggests that other factors than the blood phenobarbital concentration contribute to the magnitude of metabolic changes.

Sex-specific Associations of Sex Hormone Binding Globulin with CKD and Kidney Function: A Univariable and Multivariable Mendelian Randomization Study in the UK Biobank

BACKGROUND

Kidney function declines faster in men. Testosterone levels may mediate the sex disparity. Correspondingly, levels of sex hormone binding globulin (SHBG), which modulates sex hormones, might also be relevant to the lower kidney function in men. The sex-specific role of SHBG is unclear.

METHODS

A sex-specific, Mendelian randomization (MR) study provided unconfounded estimates of SHBG levels among the United Kingdom Biobank population. Univariable MR applied 357 single nucleotide polymorphisms (SNPs) in men and 359 SNPs in women. These published SNPs strongly (P<5×10^-8) predict SHBG level. They were profiled in 179,916 white British men (6016 patients with CKD) and 212,079 white British women (5958 patients with CKD), to obtain the effect of SHBG on CKD, albuminuria, and eGFR. Multivariable MR controlling for testosterone was used to assess the effect of SHBG on CKD and kidney function independent of testosterone in men.

RESULTS

Genetically predicted higher SHBG was associated with a lower risk of CKD in men (odds ratio [OR], 0.78 per SD; 95% confidence interval [95% CI], 0.65 to 0.93) but had no benefit in women. The effect in men remained in multivariable MR, allowing for testosterone (OR, 0.61; 95% CI, 0.45 to 0.82).

CONCLUSIONS

Genetically predicted higher SHBG was associated with a lower risk of CKD and better kidney function in men, but not in women, suggesting that SHBG may play a role in CKD specifically in men. Identifying drivers of SHBG and the underlying pathways could provide new insights into CKD prevention and treatment.

Cross-sectional and prospective relationships of endogenous progestogens and estrogens with glucose metabolism in men and women: a KORA F4/FF4 Study

INTRODUCTION

Relationships between endogenous female sex hormones and glycemic traits remain understudied, especially in men. We examined whether endogenous 17α-hydroxyprogesterone (17-OHP), progesterone, estradiol (E2), and free estradiol (fE2) were associated with glycemic traits and glycemic deterioration.

RESEARCH DESIGN AND METHODS

921 mainly middle-aged and elderly men and 390 perimenopausal/postmenopausal women from the German population-based Cooperative Health Research in the Region of Augsburg (KORA) F4/FF4 cohort study were followed up for a median of 6.4 years. Sex hormones were measured at baseline using mass spectrometry. We calculated regression coefficients (β) and ORs with 95% CIs using multivariable-adjusted linear and logistic regression models for Z-standardized hormones and glycemic traits or glycemic deterioration (ie, worsening of categorized glucose tolerance status), respectively.

RESULTS

In the cross-sectional analysis (n=1222 men and n=594 women), in men, 17-OHP was inversely associated with 2h-glucose (2hG) (β=-0.067, 95% CI -0.120 to -0.013) and fasting insulin (β=-0.074, 95% CI -0.118 to -0.030), and positively associated with Quantitative Insulin Sensitivity Check Index (QUICKI) (β=0.061, 95% CI 0.018 to 0.105). Progesterone was inversely associated with fasting insulin (β=-0.047, 95% CI -0.088 to -0.006) and positively associated with QUICKI (β=0.041, 95% CI 0.001 to 0.082). E2 was inversely associated with fasting insulin (β=-0.068, 95% CI -0.116 to -0.020) and positively associated with QUICKI (β=0.059, 95% CI 0.012 to 0.107). fE2 was positively associated with glycated hemoglobin (HbA_1c) (β=0.079, 95% CI 0.027 to 0.132). In women, 17-OHP was positively associated with fasting glucose (FG) (β=0.068, 95% CI 0.014 to 0.123). fE2 was positively associated with FG (β=0.080, 95% CI 0.020 to 0.141) and HbA_1c (β=0.121, 95% CI 0.062 to 0.180). In the sensitivity analyses restricted to postmenopausal women, we observed a positive association between 17-OHP and glycemic deterioration (OR=1.518, 95% CI 1.033 to 2.264).

CONCLUSIONS

Inter-relations exist between female sex hormones and glucose-related traits among perimenopausal/postmenopausal women and insulin-related traits among men. Endogenous progestogens and estrogens appear to be involved in glucose homeostasis not only in women but in men as well. Further well-powered studies assessing causal associations between endogenous female sex hormones and glycemic traits are warranted.

Incidence and Risk Factors of Hypogonadism in Male Patients With Latent Autoimmune Diabetes and Classic Type 2 Diabetes

OBJECTIVES

This study aimed to compare the prevalence of hypogonadism between male patients with latent autoimmune diabetes (LADA) and type 2 diabetes (T2DM) and investigate the risk factors for hypogonadism in these patients.

METHODS

This cross-sectional study evaluated 367 male patients with LADA (n=73) and T2DM (n=294) who visited the endocrinology department of Shanghai Tenth People's Hospital between January 2016 and October 2019 for diabetes management. Sex hormones, lipid profiles, sex hormone-binding globulin (SHBG), glycosylated hemoglobin A1c, beta-cell function, uric acid, and osteocalcin were determined in serum samples. Hypogonadism was defined as calculated free testosterone (cFT) less than 220 pmol/L along with the presence of symptoms (positive ADAM score).

RESULTS

The rate of hypogonadism in the LADA and T2DM group were 8.2, and 21.7%, respectively (p=0.017). After adjusting possible confounders, the rate of hypogonadism in the LADA group was comparable to those of the T2DM group. Univariate logistic regressions demonstrated that age, BMI, fasting C-peptide, triglycerides, total cholesterol and uric acid were associated with hypogonadism in men with diabetes, BMI, triglycerides and estradiol were independent risk for hypogonadism in men with diabetes.

CONCLUSION

This is the first evidence to explore the rate of hypogonadism in male patients with latent autoimmune diabetes (LADA). In the population requiring admission to a large urban hospital in China, the rate of hypogonadism was comparable to those of the T2DM group after adjusting for possible confounders. BMI, triglycerides and estradiol were independently associated with the presence of HH in male diabetic patients.

Sex Hormone-Binding Globulin Is Associated with Obesity and Dyslipidemia in Prepubertal Children

Sex hormone-binding globulin (SHBG) is associated with age, sex, and puberty. The association of SHBG with various diseases has been suggested nowadays, however, the relationships in prepubertal children have not been sufficiently investigated. This study analyzed the relationship of SHBG with body mass index (BMI) and plasma lipid levels in prepubertal children. We evaluated the association of SHBG with BMI among the 693 prepubertal children subdivided into normal, overweight, and obese groups, with plasma lipid levels among the children subdivided into normal and dyslipidemia groups. The obese and overweight group had lower SHBG levels than the normal BMI group in both sexes. The dyslipidemia group included subjects with low high-density lipoprotein cholesterol (HDL-C), high triglycerides (TG), or a high atherogenic index of plasma (AIP); this group had lower SHBG than the normal lipid group. SHBG was positively correlated with HDL-C, and negatively correlated with TG and AIP. After adjusting for BMI, SHBG was positively correlated with HDL-C and negatively correlated with TG and AIP in all groups. In conclusion, SHBG levels are closely correlated with BMI in prepubertal children. SHBG may play a meaningful role in the decrease in HDL-C and increase in TG during prepubertal age.

Circulating sex hormone binding globulin levels are modified with intensive lifestyle intervention, but their changes did not independently predict diabetes risk in the Diabetes Prevention Program

INTRODUCTION

Sex hormone binding globulin (SHBG) levels are reported to be inversely associated with diabetes risk. It is unknown whether diabetes prevention interventions increase SHBG and whether resultant changes in SHBG affect diabetes risk. The purpose of this analysis was to determine whether intensive lifestyle intervention (ILS) or metformin changed circulating SHBG and if resultant changes influenced diabetes risk in the Diabetes Prevention Program (DPP).

RESEARCH DESIGN AND METHODS

This is a secondary analysis from the DPP (1996-2001), a randomized trial of ILS or metformin versus placebo on diabetes risk over a mean follow-up of 3.2 years. The DPP was conducted across 27 academic study centers in the USA. Men, premenopausal and postmenopausal women without hormone use in the DPP were evaluated. The DPP included overweight/obese persons with elevated fasting glucose and impaired glucose tolerance. Main outcomes measures were changes in SHBG levels at 1 year and risk of diabetes over 3 years.

RESULTS

ILS resulted in significantly higher increases (postmenopausal women: p<0.01) or smaller decrements (men: p<0.05; premenopausal women: p<0.01) in SHBG compared with placebo or metformin. Changes in SHBG were primarily attributable to changes in adiposity. There were no consistent associations of change in SHBG with the risk of diabetes by treatment arm or participant group.

CONCLUSIONS

Lifestyle intervention may be associated with favorable changes in circulating SHBG, which is largely due to changes in adiposity. Changes in circulating SHBG do not independently predict reductions in diabetes incidence.

An atlas on risk factors for type 2 diabetes: a wide-angled Mendelian randomisation study

AIMS/HYPOTHESIS

The aim of this study was to use Mendelian randomisation (MR) to identify the causal risk factors for type 2 diabetes.

METHODS

We first conducted a review of meta-analyses and review articles to pinpoint possible risk factors for type 2 diabetes. Around 170 possible risk factors were identified of which 97 risk factors with available genetic instrumental variables were included in MR analyses. To reveal more risk factors that were not included in our MR analyses, we conducted a review of published MR studies of type 2 diabetes. For our MR analyses, we used summary-level data from the DIAbetes Genetics Replication And Meta-analysis consortium (74,124 type 2 diabetes cases and 824,006 controls of European ancestry). Potential causal associations were replicated using the FinnGen consortium (11,006 type 2 diabetes cases and 82,655 controls of European ancestry). The inverse-variance weighted method was used as the main analysis. Multivariable MR analysis was used to assess whether the observed associations with type 2 diabetes were mediated by BMI. We used the Benjamini-Hochberg method that controls false discovery rate for multiple testing.

RESULTS

We found evidence of causal associations between 34 exposures (19 risk factors and 15 protective factors) and type 2 diabetes. Insomnia was identified as a novel risk factor (OR 1.17 [95% CI 1.11, 1.23]). The other 18 risk factors were depression, systolic BP, smoking initiation, lifetime smoking, coffee (caffeine) consumption, plasma isoleucine, valine and leucine, liver alanine aminotransferase, childhood and adulthood BMI, body fat percentage, visceral fat mass, resting heart rate, and four plasma fatty acids. The 15 exposures associated with a decreased risk of type 2 diabetes were plasma alanine, HDL- and total cholesterol, age at menarche, testosterone levels, sex hormone binding globulin levels (adjusted for BMI), birthweight, adulthood height, lean body mass (for women), four plasma fatty acids, circulating 25-hydroxyvitamin D and education years. Eight associations remained after adjustment for adulthood BMI. We additionally identified 21 suggestive risk factors (p < 0.05), such as alcohol consumption, breakfast skipping, daytime napping, short sleep, urinary sodium, and certain amino acids and inflammatory factors.

CONCLUSIONS/INTERPRETATION

The present study verified several previously reported risk factors and identified novel potential risk factors for type 2 diabetes. Prevention strategies for type 2 diabetes should be considered from multiple perspectives on obesity, mental health, sleep quality, education level, birthweight and smoking.

Sex hormone-binding globulin regulates the activity of the ERK pathway in the placentas of patients with gestational diabetes mellitus

The sex hormone-binding globulin (SHBG) is involved in the onset and progression of insulin resistance and metabolic syndromes, with its expression downregulated in the placental tissues of patients with gestational diabetes mellitus (GDM). However, the underlying mechanisms for these effects remain unclear. In this study, we enrolled an equal number (30) of GDM and non-GDM puerperae who underwent cesarean section at Shengjing Hospital. After due approval by the ethics committee, the expression levels of SHBG and extracellular-signal-regulated kinase (ERK) pathway markers in the placental tissues of these individuals were measured via reverse transcription-polymerase chain reaction (RT-PCR) and Western blot assays. The correlation analysis of these genes revealed that the expression of SHBG in placental tissues was downregulated and negatively correlated with the expression of ERK pathway markers, which were upregulated in placental tissues. Further investigations using the HTR-8/SVneo trophoblast cell line revealed that the trophoblasts with small interfering RNA (siRNA)-silenced SHBG expression displayed increased mRNA and protein expression levels of ERK pathway markers, as well as reduced apoptosis and enhanced proliferation. In contrast, trophoblasts with high SHBG expression showed a downregulated expression of ERK pathway markers, increased apoptosis, reduced proliferation, and a shorter S phase. Therefore, we believe that SHBG may participate in the onset of insulin resistance and GDM by regulating the activity of the ERK pathway.

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.

Serum SHBG Is Associated With the Development and Regression of Nonalcoholic Fatty Liver Disease: A Prospective Study

CONTEXT

SHBG, a homodimeric glycoprotein produced by hepatocytes has been shown to be associated with metabolic disorders. Whether circulating SHBG levels are predictive of later risk of nonalcoholic fatty liver disease (NAFLD) remains unknown. In this study, we prospectively investigated the association between SHBG and NAFLD progression through a community-based cohort comprising 3389 Chinese adults.

METHODS

NAFLD was diagnosed using abdominal ultrasonography. Serum SHBG levels were measured by chemiluminescent enzyme immunometric assay, and their relationship with NAFLD development and regression was investigated after a mean follow-up of 3.09 years using multivariable logistic regression.

RESULTS

Basal SHBG was negatively associated with NAFLD development, with a fully adjusted odds ratio (OR) and its 95% confidence interval (CI) of 0.22 (0.12-0.40) (P < .001). In contrast, basal SHBG was positively associated with NAFLD regression, with a fully adjusted OR of 4.83 (2.38-9.81) (P < .001). Multiple-stepwise logistic regression analysis showed that SHBG concentration was an independent predictor of NAFLD development (OR, 0.28 [0.18-0.45]; P < .001) and regression (OR, 3.89 [2.43-6.22]; P < .001). In addition, the area under the receiver operating characteristic curves were 0.764 (95% CI, 0.740-0.787) and 0.762 (95% CI, 0.738-0.785) for the prediction models of NAFLD development and regression, respectively.

CONCLUSIONS

Serum SHBG concentration is associated with the development and regression of NAFLD; moreover, it can be a potential biomarker for predicting NAFLD progression, and also a novel preventive and therapeutic target for NAFLD.

Decreased Sex Hormone-Binding Globulin Indicated Worse Biometric, Lipid, Liver, and Renal Function Parameters in Women with Polycystic Ovary Syndrome

OBJECTIVE

To investigate the relationships between sex hormone-binding globulin (SHBG) and comprehensive metabolic parameters including biometric, glycemic, lipid, liver, and renal functions of women with polycystic ovary syndrome (PCOS). Study Design and Methods. A total of 1000 women diagnosed as PCOS by modified Rotterdam criteria were enrolled in a randomized controlled trial. SHBG and comprehensive metabolic parameters were measured at the baseline visit. Metabolic parameters included biometric parameters, glucose and lipid panels, and liver and renal function parameters. An independent t-test and linear regression were performed to investigate the associations between SHBG and metabolic parameters. Logistic regression was used to detect the relationship between SHBG and the presence of metabolic syndrome.

RESULTS

In comparative analyses, PCOS women with lower SHBG levels had higher body mass index, waist circumference, insulin, homeostatic model assessment-insulin resistance (HOMA-IR) index, systolic and diastolic blood pressure, triglycerides, apolipoprotein B (APOB), low-density lipoprotein (LDL), aspartate transferase (AST), alanine transferase (ALT), and blood urea nitrogen (BUN), but lower high-density lipoprotein (HDL) and apolipoprotein A1 (APOA1). In linear regression, SHBG was inversely associated with waist circumference, systolic blood pressure, triglyceride, LDL, APOB, ALT, AST, and BUN but positively associated with HDL and APOA1 after adjusting the BMI. In logistic regression, SHBG is a protective predictor for metabolic syndrome (odds ratio = 0.96; 95% confidence interval: 0.95-0.97). The area under the receiver-operator characteristic curve is 0.732 with a 95% confidence interval of 0.695-0.770. SHBG <26.75 mmol/L is the cutoff point with the best Youden index, which has a sensitivity of 0.656 and specificity of 0.698.

CONCLUSIONS

Lower SHBG was associated with worsening biometric, lipid, liver, and renal functions but not glycemic parameters among women with PCOS. SHBG can be used as a tool to screen metabolic syndrome. This trial is registered with NCT01573858 and ChiCTR-TRC-12002081.

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.

Insulin resistance and systemic metabolic changes in oral glucose tolerance test in 5340 individuals: an interventional study

BACKGROUND

Insulin resistance (IR) is predictive for type 2 diabetes and associated with various metabolic abnormalities in fasting conditions. However, limited data are available on how IR affects metabolic responses in a non-fasting setting, yet this is the state people are mostly exposed to during waking hours in the modern society. Here, we aim to comprehensively characterise the metabolic changes in response to an oral glucose test (OGTT) and assess the associations of these changes with IR.

METHODS

Blood samples were obtained at 0 (fasting baseline, right before glucose ingestion), 30, 60, and 120 min during the OGTT. Seventy-eight metabolic measures were analysed at each time point for a discovery cohort of 4745 middle-aged Finnish individuals and a replication cohort of 595 senior Finnish participants. We assessed the metabolic changes in response to glucose ingestion (percentage change in relative to fasting baseline) across the four time points and further compared the response profile between five groups with different levels of IR and glucose intolerance. Further, the differences were tested for covariate adjustment, including gender, body mass index, systolic blood pressure, fasting, and 2-h glucose levels. The groups were defined as insulin sensitive with normal glucose (IS-NGT), insulin resistant with normal glucose (IR-NGT), impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and new diabetes (NDM). IS-NGT and IR-NGT were defined as the first and fourth quartile of fasting insulin in NGT individuals.

RESULTS

Glucose ingestion induced multiple metabolic responses, including increased glycolysis intermediates and decreased branched-chain amino acids, ketone bodies, glycerol, and triglycerides. The IR-NGT subgroup showed smaller responses for these measures (mean + 23%, interquartile 9-34% at 120 min) compared to IS-NGT (34%, 23-44%, P < 0.0006 for difference, corrected for multiple testing). Notably, the three groups with glucose abnormality (IFG, IGT, and NDM) showed similar metabolic dysregulations as those of IR-NGT. The difference between the IS-NGT and the other subgroups was largely explained by fasting insulin, but not fasting or 2 h glucose. The findings were consistent after covariate adjustment and between the discovery and replication cohort.

CONCLUSIONS

Insulin-resistant non-diabetic individuals are exposed to a similar adverse postprandial metabolic milieu, and analogous cardiometabolic risk, as those with type 2 diabetes. The wide range of metabolic abnormalities associated with IR highlights the necessity of diabetes diagnostics and clinical care beyond glucose management.

Metabolic profiling of adolescent non-alcoholic fatty liver disease

Background: Adolescent non-alcoholic fatty liver disease (NAFLD) is associated with cardiometabolic risk factors. The association between adolescent NAFLD and a wide range of metabolic biomarkers is unclear. We have attempted to determine the differences in metabolic profile of adolescents with and without markers of NAFLD. Methods: We performed cross-sectional analyses in a sample of 3,048 participants from the Avon Longitudinal Study of Parents and Children at age 17. We used three indicators of NAFLD: ALT >40 U/l; AST >40 U/l and ultrasound scan-assessed steatosis. Associations between each measure of NAFLD and 154 metabolic traits, assessed by Nuclear Magnetic Resonance, were analyzed by multivariable linear regression, adjusting for age, sex and BMI. Results: All three indicators of NAFLD were associated with ~0.5 standard deviation (SD) greater concentrations of all extremely large to small very low-density lipoproteins (VLDL) measures. ALT >40U/l was associated with ~0.5SD greater concentrations of very small VLDLs, intermediate-density lipoproteins and low-density lipoproteins. Concentrations of most cholesterols, including remnant cholesterol, all triglycerides and monounsaturated fatty acids, in addition to glycoprotein acetyls (inflammatory marker), were also higher in participants with NAFLD. Conclusions: We have identified differing metabolic profiles between adolescents with and without indicators of NAFLD. These results provide the foundations for future research to determine whether these differences persist and result in adverse future cardiometabolic health.

Metabolic profiling of adolescent non-alcoholic fatty liver disease

Background: Adolescent non-alcoholic fatty liver disease (NAFLD) is associated with cardiometabolic risk factors. The association between adolescent NAFLD and a wide range of metabolic biomarkers is unclear. We have attempted to determine the differences in metabolic profile of adolescents with and without markers of NAFLD. Methods: We performed cross-sectional analyses in a sample of 3,048 participants from the Avon Longitudinal Study of Parents and Children at age 17. We used three indicators of NAFLD: ALT >40 U/l; AST >40 U/l and ultrasound scan-assessed steatosis. Associations between each measure of NAFLD and 154 metabolic traits, assessed by Nuclear Magnetic Resonance, were analyzed by multivariable linear regression, adjusting for age, sex and BMI. Results: All three indicators of NAFLD were associated with ~0.5 standard deviation (SD) greater concentrations of all extremely large to small very low-density lipoproteins (VLDL) measures. ALT >40U/l was associated with ~0.5SD greater concentrations of very small VLDLs, intermediate-density lipoproteins and low-density lipoproteins. Concentrations of most cholesterols, including remnant cholesterol, all triglycerides and monounsaturated fatty acids, in addition to glycoprotein acetyls (inflammatory marker), were also higher in participants with NAFLD. Conclusions: We have identified differing metabolic profiles between adolescents with and without indicators of NAFLD. These results provide the foundations for future research to determine whether these differences persist and result in adverse future cardiometabolic health.

Genetic and observational evidence supports a causal role of sex hormones on the development of asthma

INTRODUCTION

Males have a higher prevalence of asthma in childhood, whereas females have a higher prevalence in adolescence and adulthood. The 'adolescent switch' observed between sexes during puberty has been hypothesised to be due to fluctuating sex hormones. Robust evidence of the involvement of sex hormones in asthma could lead to development of therapeutic interventions.

METHODS

We combine observational evidence using longitudinal data on sex hormone-binding globulin (SHBG), total and bioavailable testosterone and asthma from a subset of males (n=512) in the Avon Longitudinal Study of Parents and Children, and genetic evidence of SHBG and asthma using two-sample Mendelian randomisation (MR), a method of causal inference. We meta-analysed two-sample MR results across two large data sets, the Trans-National Asthma Genetics Consortium genome-wide association study of asthma and UK Biobank (over 460 000 individuals combined).

RESULTS

Observational evidence indicated weak evidence of a protective effect of increased circulating testosterone on asthma in males in adolescence, but no strong pattern of association with SHBG. Genetic evidence using two-sample MR indicated a protective effect of increased SHBG, with an OR for asthma of 0.86 (95% CI 0.74 to 1.00) for the inverse-variance weighted approach and an OR of 0.83 (95% CI 0.72 to 0.96) for the weighted median estimator, per unit increase in natural log SHBG. A sex-stratified sensitivity analysis suggested the protective effect of SHBG was mostly evident in females.

CONCLUSION

We report the first suggestive evidence of a protective effect of genetically elevated SHBG on asthma, which may provide a biological explanation behind the observed asthma sex discordance. Further work is required to disentangle the downstream effects of SHBG on asthma and the molecular pathways involved.

Does sex hormone-binding globulin cause insulin resistance during pubertal growth?

BACKGROUND

The directional influences between serum sex hormone-binding globulin (SHBG), adiposity and insulin resistance during pubertal growth remain unclear. The aim of this study was to investigate bidirectional associations between SHBG and insulin resistance (HOMA-IR) and adiposity from childhood to early adulthood.

METHODS

Participants were 396 healthy girls measured at baseline (age 11.2 years) and at 1, 2, 4 and 7.5 years. Serum concentrations of estradiol, testosterone and SHBG were determined by ELISA, glucose and insulin by enzymatic photometry, insulin-like growth factor 1 (IGF-1) by time-resolved fluoroimmunoassays, whole-body fat mass by dual-energy X-ray absorptiometry and HOMA-IR were determined by homeostatic model assessment. The associations were examined using cross-lagged path models.

RESULTS

In a cross-lagged path model, SHBG predicted HOMA-IR before menarche β = -0.320 (95% CI: -0.552 to -0.089), P = 0.007, independent of adiposity and IGF-1. After menarche, no directional effect was found between SHBG and insulin resistance or adiposity.

CONCLUSIONS

Our results suggest that in early puberty, decline in SHBG predicts development of insulin resistance, independent of adiposity. However, after menarche, no directional influences between SHBG, adiposity and insulin resistance were found, suggesting that observational associations between SHBG, adiposity and insulin resistance in pubertal children may be subject to confounding. Further research is needed to understand the underlying mechanisms of the associations between SHBG and cardiometabolic risk markers in peripubertal children.

Investigating the effects of lycopene and green tea on the metabolome of men at risk of prostate cancer: The ProDiet randomised controlled trial

Lycopene and green tea consumption have been observationally associated with reduced prostate cancer risk, but the underlying mechanisms have not been fully elucidated. We investigated the effect of factorial randomisation to a 6-month lycopene and green tea dietary advice or supplementation intervention on 159 serum metabolite measures in 128 men with raised PSA levels (but prostate cancer-free), analysed by intention-to-treat. The causal effects of metabolites modified by the intervention on prostate cancer risk were then assessed by Mendelian randomisation, using summary statistics from 44,825 prostate cancer cases and 27,904 controls. The systemic effects of lycopene and green tea supplementation on serum metabolic profile were comparable to the effects of the respective dietary advice interventions (R2 = 0.65 and 0.76 for lycopene and green tea respectively). Metabolites which were altered in response to lycopene supplementation were acetate [β (standard deviation difference vs. placebo): 0.69; 95% CI = 0.24, 1.15; p = 0.003], valine (β: -0.62; -1.03, -0.02; p = 0.004), pyruvate (β: -0.56; -0.95, -0.16; p = 0.006) and docosahexaenoic acid (β: -0.50; -085, -0.14; p = 0.006). Valine and diacylglycerol were lower in the lycopene dietary advice group (β: -0.65; -1.04, -0.26; p = 0.001 and β: -0.59; -1.01, -0.18; p = 0.006). A genetically instrumented SD increase in pyruvate increased the odds of prostate cancer by 1.29 (1.03, 1.62; p = 0.027). An intervention to increase lycopene intake altered the serum metabolome of men at risk of prostate cancer. Lycopene lowered levels of pyruvate, which our Mendelian randomisation analysis suggests may be causally related to reduced prostate cancer risk.

Relationship between umbilical cord sex hormone binding globulin, sex steroids, and age at menarche: a prospective cohort study

OBJECTIVE

To study the role of the prenatal environment in regulating reproductive development by measuring the prospective association between umbilical cord concentrations of sex hormone binding globulin (SHBG; principal regulator of sex steroid activity), bioavailable sex steroids, and age at menarche.

DESIGN

Prospective population-based cohort.

SETTING

Not applicable.

PATIENT(S)

In 286 female members of the Western Australian Pregnancy (Raine) cohort, concentrations of SHBG and steroids (estrogens: estrone, estradiol, estriol and estetrol [E4]; androgens: total testosterone, Δ4-androstenedione, androstenedione and dehydroepiandrosterone) were measured by liquid chromatography-tandem mass spectrometry from archived umbilical cord blood samples collected at birth. Bioavailable concentrations of testosterone and estradiol were calculated along with total composite measures of androgen and estrogen bioactivity. SHBG was measured by ELISA.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Age of menarche was calculated from date of menarche, collected prospectively by questionnaire sent home with participants at the year 10 follow-up.

RESULT(S)

Higher maternal education, higher body mass index, and the presence of antepartum hemorrhage were all significantly associated with earlier age at menarche. The bioavailable sex steroid measures accounted for 8.3% of the variance in age at menarche. Further, both SHBG and E4 concentrations accounted for a significant proportion of unique variance in age at menarche.

CONCLUSION(S)

Lower SHBG and higher E4 concentrations in umbilical cord blood were associated with earlier age at menarche. These results suggest that the prenatal sex steroid environment contributes toward pubertal development and age at menarche.

Are there differences in basal thrombophilias and C-reactive protein between women with or without PCOS?

RESEARCH QUESTION

Polycystic ovary syndrome (PCOS) women have increased cardiovascular risks, although it is unclear whether the haemostatic system and coagulation contribute to that increased risk.

DESIGN

Women attending the Gynecology Unit of the 'Virgen de la Arrixaca' University Hospital (Murcia, Spain) for routine gynaecological examinations between September 2014 and May 2016 were assessed for PCOS using the Rotterdam criteria (hyperandrogenism [H], oligo/amenorrhoea [O] and polycystic ovarian morphology [POM]) and were classified into four phenotypic. In total, 126 cases were identified and 159 control women were selected. All women underwent physical and gynaecological examinations, and blood tests between the second and fifth day of the menstrual cycle. Differences in hormonal, basal thrombophilia and metabolic parameters, and C-reactive protein (CRP) between PCOS and controls were analysed.

RESULTS

After adjusting by BMI and age, PCOS women had higher LH (P < 0.001), testosterone (P < 0.001), free testosterone (P = 0.01) and anti-Müllerian hormone (P < 0.001) and lower FSH (P = 0.03) compared with controls, whereas sex hormone-binding globulin was no different. Cases showed significantly higher protein S, glucose, insulin and insulin resistance (HOMA-IR) compared with controls (P < 0.05). There were no differences in protein C levels, antithrombin III, prothrombin time, homocysteine, D-dimer, factor V Leyden, prothrombin G20210A polymorphism or CRP. The H+O phenotype showed the poorest results for insulin and HOMA-IR (P = 0.04 and 0.05).

CONCLUSIONS

The results suggest that there are no differences in the basal thrombophilias between women with and without PCOS. However, PCOS with H+O shows the poorest metabolic profile.

Sex hormone levels by presence and severity of cirrhosis in women with chronic hepatitis C virus infection

Cirrhosis is associated with hormonal dysregulation, as evidenced by secondary amenorrhoea in reproductive-aged women, and feminization of cirrhotic men. Whether hormone levels vary by severity of cirrhosis in women is not known. If identified, such changes may have important clinical relevance, particularly, as low sex hormone binding globulin (SHBG) and follicle stimulating hormone (FSH) are known to promote metabolic and cardiovascular disease in women. In a cohort of post-menopausal women with chronic hepatitis C virus (HCV) infection, we compared comprehensive sex hormone levels by presence of cirrhosis, as well as across Child-Turcotte-Pugh (CTP) class. Results: There were n = 18 cirrhotic and n = 21 noncirrhotic women with a median age of 57 years (interquartile range [IQR] 53-62). Compared to noncirrhotics, cirrhotic women had higher oestradiol (11.0 vs 6.0 pg/mL, P = 0.05) and oestrone levels (32.0 vs 8.0 ng/mL, P < 0.001), and lower sex hormone binding globulin (SHBG) (69.2 vs 155.6 nmol/L, P = 0.001), and FSH levels (4.9 vs 89.6 mIU/mL, P < 0.001). Among cirrhotic women, there was a progressive decline in FSH and SHBG and concurrent rise in oestrone levels from CTP class A to C (test of trend, P values ≤0.02). Cirrhosis is associated with lower FSH and SHBG levels in cirrhotic compared to noncirrhotic women with HCV infection. In cirrhotic women, these levels demonstrate steady decline by disease severity. Given known associations of low SHBG and FSH with cardio-metabolic disease, the clinical implications of hormonal changes by cirrhosis severity in HCV-infected women warrants investigation.

Cognition, psychosis risk and metabolic measures in two adolescent birth cohorts

BACKGROUND

Psychoses, especially schizophrenia, are often preceded by cognitive deficits and psychosis risk states. Altered metabolic profiles have been found in schizophrenia. However, the associations between metabolic profiles and poorer cognitive performance and psychosis risk in the population remain to be determined.

METHODS

Detailed molecular profiles were measured for up to 8976 individuals from two general population-based prospective birth cohorts: the Northern Finland Birth Cohort 1986 (NFBC 1986) and the Avon Longitudinal Study of Parents and Children (ALSPAC). A high-throughput nuclear magnetic resonance spectroscopy platform was used to quantify 70 metabolic measures at age 15-16 years in the NFBC 1986 and at ages 15 and 17 years in ALSPAC. Psychosis risk was assessed using the PROD-screen questionnaire at age 15-16 years in the NFBC 1986 or the psychotic-like symptoms assessment at age 17 years in ALSPAC. Cognitive measures included academic performance at age 16 years in both cohorts and general intelligence and executive function in ALSPAC. Logistic regression measured cross-sectional and longitudinal associations between metabolic measures and psychosis risk and cognitive performance, controlling for important covariates.

RESULTS

Seven metabolic measures, primarily fatty acid (FA) measures, showed cross-sectional associations with general cognitive performance, four across both cohorts (low density lipoprotein diameter, monounsaturated FA ratio, omega-3 ratio and docosahexaenoic acid ratio), even after controlling for important mental and physical health covariates. Psychosis risk showed minimal metabolic associations.

CONCLUSIONS

FA ratios may be important in marking risk for cognitive deficits in adolescence. Further research is needed to clarify whether these biomarkers could be causal and thereby possible targets for intervention.

Circulating sex hormone binding globulin: An integrating biomarker for an adverse cardio-metabolic profile in obese pregnant women

Sex hormone-binding globulin (SHBG) negatively associates with pre-gestational body mass index (BMI) and gestational weight gain. The link with other cardio-metabolic risk factors in pregnant women is poorly understood. Our aim was to study the association of SHBG levels with common cardio-metabolic risk parameters in pregnant woman.

Serum SHBG was quantified in 291 Caucasian pregnant women (142 with normal weight, 42 with pregestational obesity, 50 with gestational obesity and 57 with pregestational plus gestational obesity) with uncomplicated pregnancies and parturition. Cardio-metabolic [C-reactive protein (CRP), blood pressure (BP), glycosylated hemoglobin (HbAc1), glucose, C-peptide, insulin, triglycerides and high molecular weight (HMW) adiponectin], and endocrine [testosterone and estradiol] parameters were also assessed.

SHBG was negatively correlated with BMI, but also with CRP, BP, HbAc1, pre and post-load glucose, C-peptide, HOMA-IR, triglycerides; and positively with HMW adiponectin (all p<0.01 to p<0.0001). These associations were more robust in women with pregestational plus gestational obesity, who had lower SHBG, in comparison to normal-weight women (p<0.0001). In multivariate analyses in women with pregestational plus gestational obesity SHBG showed independent associations with CRP (β = −0.352, p = 0.03, R² = 8.0%), DBP (β = −0.353, p = 0.03, R² = 7.0%) and SBP (β = −0.333, p = 0.04, R² = 6.0%) independently of BMI and metabolic and endocrine parameters.

SHBG is decreased in pregnant women with pregestational plus gestational obesity in association with common cardio-metabolic parameters. SHBG could represent an integrating biomarker for an adverse cardio-metabolic profile in pregnant women with pregestational plus gestational obesity.

A Pre-Pregnancy Biomarker Risk Score Improves Prediction of Future Gestational Diabetes

CONTEXT

Previous studies have not examined the ability of multiple preconception biomarkers, considered together, to improve prediction of gestational diabetes mellitus (GDM).

OBJECTIVE

To develop a preconception biomarker risk score and assess its association with subsequent GDM.

DESIGN

A nested case-control study among a cohort of women with serum collected as part of a health examination (1984 to 1996) and subsequent pregnancy (1984 to 2009). Biomarkers associated with GDM were dichotomized into high/low risk.

SETTING

Integrated health care system.

PARTICIPANTS

Two controls were matched to each GDM case (n = 256 cases) on year and age at examination, age at pregnancy, and number of pregnancies between examination and index pregnancy.

MAIN OUTCOME MEASURE

GDM.

RESULTS

High-risk levels of sex hormone-binding globulin (SHBG; <44.2 nM), glucose (>90 mg/dL), total adiponectin (<7.2 μg/mL), and homeostasis model assessment-estimated insulin resistance (>3.9) were independently associated with 2.34 [95% confidence interval (CI): 1.50, 3.63], 2.03 (95% CI: 1.29, 3.19), 1.83 (95% CI: 1.16, 2.90), and 1.67 (95% CI: 1.07, 2.62) times the odds of GDM and included in the biomarker risk score. For each unit increase in the biomarker risk score, odds of GDM were 1.94 times greater (95% CI: 1.59, 2.36). A biomarker risk score including only SHBG and glucose was sufficient to improve prediction beyond established risk factors (age, race/ethnicity, body mass index, family history of diabetes, previous GDM; area under the curve = 0.73 vs 0.67, P = 0.002).

CONCLUSIONS

The improved, predictive ability of the biomarker risk score beyond established risk factors suggests clinical use of the biomarker risk score in identifying women at risk for GDM before conception for targeted prevention strategies.

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

AIMS

Contrasting findings exist regarding the association between circulating sex hormone-binding globulin (SHBG) and testosterone levels and type 2 diabetes (T2D) in men. We examined prospective associations of SHBG and sex steroids with incident T2D in a cohort of community-dwelling men.

METHODS

Participants were from a cohort study of community-dwelling (n = 2563), middle-aged to elderly men (35-80 years) from Adelaide, Australia (the Men Androgen Inflammation Lifestyle Environment and Stress (MAILES) study). The current study included men who were followed for 5 years and with complete SHBG and sex steroid levels (total testosterone (TT), dihydrotestosterone (DHT) and oestradiol (E2)), but without T2D at baseline (n = 1597). T2D was identified by either self-report, fasting glucose (≥ 7.0 mmol/L), HbA1c (≥ 6.5%/48.0 mmol/mol), and/or prescriptions for diabetes medications. Logistic binomial regression was used to assess associations between SHBG, sex steroids and incident T2D, adjusting for confounders including age, smoking status, physical activity, adiposity, glucose, triglycerides, symptomatic depression, SHBG and sex steroid levels.

RESULTS

During an average follow-up of 4.95 years, 14.5% (n = 232) of men developed new T2D. Multi-adjusted models revealed an inverse association between baseline SHBG, TT, and DHT levels, and incident T2D (odds ratio (OR) = 0.77, 95% CI [0.62, 0.95], p = 0.02; OR 0.70 [0.57, 0.85], p < 0.001 and OR 0.78 [0.63, 0.96], p = 0.02), respectively. However, SHBG was no longer associated with incident T2D after additional adjustment for TT (OR 0.92 [0.71, 1.17], p = 0.48; TT in incident T2D: OR 0.73 [0.57, 0.92], p = 0.01) and after separate adjustment for DHT (OR 0.83 [0.64, 1.08], p = 0.16; DHT in incident T2D: OR 0.83 [0.65, 1.05], p = 0.13). There was no observed effect of E2 in all models of incident T2D.

CONCLUSIONS

In men, low TT, but not SHBG and other sex steroids, best predicts the development of T2D after adjustment for confounders.

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.