Testosterone replacement therapy improves insulin resistance, glycaemic control, visceral adiposity and hypercholesterolaemia in hypogonadal men with type 2 diabetes

Investigating the basis of sexual dysfunction during late-onset hypogonadism

Late-onset hypogonadism (LOH) is the term used to describe the decline in serum testosterone levels associated with increasing age in men above 40 years. A number of symptoms are attributed to LOH, but the most common association is that of sexual dysfunction. LOH has recently come under greater scrutiny with the widespread use of testosterone therapy, and concerns regarding the efficacy and safety of testosterone replacement therapy have been raised. In particular, the cardiovascular safety and the beneficial effects of testosterone replacement therapy on general health have been questioned. This review will give an overview of the current evidence for the relationship of LOH and male sexual dysfunction.

Association between dietary glycemic index and liver enzymes level among apparently healthy adults

OBJECTIVE

The previous studies have revealed that there is a link between dietary glycemic index and lipid profile in overweight and obesity. The aim of study was to investigate whether the glycemic index is associated with liver enzymes.

METHOD

Anthropometric and biochemical parameters were measured in 265 participants. Dietary glycemic index (GI) was assessed by using a validated food-frequency questionnaire. With adjusting confounder variable, Binary logistic regression was also used to predict the relationship between liver enzymes and quartile of intake.

RESULTS

There was a significant difference between low and high GI diet for BMR (P = 0.01), FFM (P = 0.03), TG (P = 0.02), HDL (P = 0.002). The association between HDL and glycemic index remained significant after adjustment of sex and age (P = 0.03). Using the regression model following adjustment revealed that for each 1% increase in the degree of the GI, there was 11% elevation in liver enzyme abnormalities. In both groups of men and women, enzyme abnormalities positively correlated with GI, while only men showed remarkable correlation in all models (crude model: β = 0.07, OR = 1.07, CI = 0.98to 1.16). Additionally, an increase in the degree of GI caused an elevation in enzyme abnormalities by 7%. With adjusting sex, age, BMI, and Physical activity, a significance correlation was found between GI and Enzyme abnormalities (p-value = 0.03, OR = 1.115).

CONCLUSION

Our study indicated that high glycemic index diet led to the elevated levels of the liver enzymes, while being significant only in men.

The effects of testosterone replacement therapy on the prostate: a clinical perspective

Male hypogonadism is a clinical syndrome characterized by low testosterone and symptoms of androgen deficiency. Prostate cancer remains a significant health burden and cause of male mortality worldwide. The use of testosterone replacement therapy drugs is rising year-on-year for the treatment of androgen deficiency and has reached global proportions. As clinicians, we must be well versed and provide appropriate counseling for men prior to the commencement of testosterone replacement therapy. This review summarizes the current clinical and basic science evidence in relation to this commonly encountered clinical scenario. There is gathering evidence that suggests, from an oncological perspective, that it is safe to commence testosterone replacement therapy for men who have a combination of biochemically confirmed androgen deficiency and who have either had definitive treatment of their prostate cancer or no previous history of this disease. However, patients must be made aware and cautioned that there is a distinct lack of level 1 evidence. Calls for such studies have been made throughout the urological and andrological community to provide a definitive answer. For those with a diagnosis of prostate cancer that remains untreated, there is a sparsity of evidence and therefore clinicians are “pushing the limits” of safety when considering the commencement of testosterone replacement therapy.

Effects of short-term sex steroid suppression on dietary fat storage patterns in healthy males

Hypogonadism in males is associated with increased body fat and altered postprandial metabolism, but mechanisms remain poorly understood. Using a cross‐over study design, we investigated the effects of short‐term sex hormone suppression with or without testosterone add‐back on postprandial metabolism and the fate of dietary fat. Eleven healthy males (age: 29 ± 4.5 year; BMI: 26.3 ± 2.1 kg/m²) completed two 7‐day study phases during which hormone levels were altered pharmacologically to produce a low sex hormone condition (gonadotropin releasing hormone antagonist, aromatase inhibitor, and placebo gel) or a testosterone add‐back condition (testosterone gel). Following 7 days of therapy, subjects were administered an inpatient test meal containing 50 μCi of [1‐¹⁴C] oleic acid. Plasma samples were collected hourly for 5 h to assess postprandial responses. Energy metabolism (indirect calorimetry) and dietary fat oxidation (¹⁴CO₂ in breath) were assessed at 1, 3, 5, 13.5, and 24 h following the test meal. Abdominal and femoral adipose biopsies were taken 24 h after the test meal to determine uptake of the labeled lipid. Postprandial glucose, insulin, free‐fatty acid, and triglyceride responses were not different between conditions (P > 0.05). Whole‐body energy metabolism was also not different between conditions at any time point (P > 0.05). Dietary fat oxidation trended lower (P = 0.12) and the relative uptake of ¹⁴C labeled lipid into femoral adipose tissue was greater (P = 0.03) in the low hormone condition. Short‐term hormone suppression did not affect energy expenditure or postprandial metabolism, but contributed to greater relative storage of dietary fat in the femoral depot. ClinicalTrials.gov Identifier: NCT03289559.

Metabolic Disorders and Male Hypogonadotropic Hypogonadism

Several studies highlight that testosterone deficiency is associated with, and predicts, an increased risk of developing metabolic disorders, and, on the other hand, is highly prevalent in obesity, metabolic syndrome and type-2 diabetes mellitus. Models of gonadotropin releasing hormone deficiency, and androgen deprivation therapy in patients with prostate cancer, suggest that hypogonadotropic hypogonadism might contribute to the onset or worsening of metabolic conditions, by increasing visceral adiposity and insulin resistance. Nevertheless, in functional hypogonadism, as well as in late onset hypogonadism, the relationship between hypogonadotropic hypogonadism and metabolic disorders is bidirectional, and a vicious circle between the two components has been documented. The mechanisms underlying the crosstalk between testosterone deficiency and metabolic disorders include increased visceral adipose tissue and insulin resistance, leading to development of metabolic disorders, which in turn contribute to a further reduction of testosterone levels. The decrease in testosterone levels might be determined by insulin resistance-mediated and, possibly, pro-inflammatory cytokine-mediated decrease of sex hormone binding globulin, resulting in a temporary increased free testosterone available for aromatization to estradiol in visceral adipose tissue, followed by a subsequent decrease in free testosterone levels, due to the excess of visceral adipose tissue and aromatization; by a direct inhibitory effect of increased leptin levels on Leydig cells; and by a reduced gonadotropin secretion induced by estradiol, inflammatory mediators, leptin resistance, and insulin resistance, with the ultimate determination of a substantial hypogonadotropic hypogonadism. The majority of studies focusing on the effects of testosterone replacement therapy on metabolic profile reported a beneficial effect of testosterone on body weight, waist circumference, body mass index, body composition, cholesterol levels, and glycemic control. Consistently, several interventional studies demonstrated that correction of metabolic disorders, in particular with compounds displaying a greater impact on body weight and insulin resistance, improved testosterone levels. The aim of the current review is to provide a comprehensive overview on the relationship between hypogonadotropic hypogonadism and metabolism, by clarifying the independent role of testosterone deficiency in the pathogenesis of metabolic disorders, and by describing the relative role of testosterone deficiency and metabolic impairment, in the context of the bidirectional relationship between hypogonadism and metabolic diseases documented in functional hypogonadotropic hypogonadism. These aspects will be assessed by describing metabolic profile in men with hypogonadotropic hypogonadism, and androgenic status in men with metabolic disorders; afterwards, the reciprocal effects of testosterone replacement therapy and corrective interventions on metabolic derangements will be reported.

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

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

Clinical efficacy of free androgen index, a surrogate hallmark of circulating free testosterone level, in male patients with HCV-related chronic liver disease

The role of free testosterone, that not bound to sex hormone-binding globulin, in male patients with HCV infection remains uncertain. We investigated whether free testosterone is involved in the progression to hepatic fibrosis/steatosis or insulin resistance in male patients with HCV-related chronic liver disease or not. Free androgen indices, which reflect circulating free testosterone levels, were calculated as 100 × total testosterone levels/sex hormone-binding globulin levels in 30 male patients with HCV-related chronic liver disease. Degrees of hepatic fibrosis and steatosis were evaluated by the New Inuyama Classification and the classification proposed by Brunt and colleagues, respectively. Insulin resistance was estimated by HOMA-IR values. Serum total testosterone levels were independent of hepatic fibrosis staging in the enrolled patients. However, circulating sex hormone-binding globulin levels were significantly increased in proportion to the severity of hepatic fibrosis. Therefore, free androgen indices were inversely correlated with the severity of hepatic fibrosis. Moreover, free androgen indices were inversely correlated with the grades of hepatic steatosis and HOMA-IR values in those patients. Our data suggest that lower circulating free testosterone levels may be recognized as the risk factor for more advanced hepatic fibrosis, steatosis and/or higher insulin resistance in male patients with HCV-related chronic liver disease.

The Glucose-Lowering Effect of Foxtail Millet in Subjects with Impaired Glucose Tolerance: A Self-Controlled Clinical Trial

Foxtail millet has relatively low starch digestibility and moderate glycemic index compared to other grains. Since there are still no clinical researches regarding its long-term effect on blood glucose, this self-controlled study was conducted to investigate the glucose-lowering effect of foxtail millet in free-living subjects with impaired glucose tolerance (IGT). Fifty g/day of foxtail millet was provided to enrolled subjects throughout 12 weeks and the related clinical parameters were investigated at week 0, 6 and 12, respectively. After 12 weeks of foxtail millet intervention, the mean fasting blood glucose of the subjects decreased from 5.7 ± 0.9 mmol/L to 5.3 ± 0.7 mmol/L (p < 0.001) and the mean 2 h-glucose decreased from 10.2 ± 2.6 mmol/L to 9.4 ± 2.3 mmol/L (p = 0.003). The intake of foxtail millet caused a significant increase of serum leptin (p = 0.012), decrease of insulin resistance (p = 0.007), and marginal reduction of inflammation. Furthermore, a sex-dependent difference in glucose-lowering effect of foxtail millet was observed in this study. Foxtail millet could improve the glycemic control in free-living subjects with IGT, suggesting that increasing the consumption of foxtail millet might be beneficial to individuals suffering from type 2 diabetes mellitus.

Potential application of testosterone replacement therapy as treatment for obesity and type 2 diabetes in men

Sedentary lifestyle and over-nutrition are the main causes of obesity and type 2 diabetes (T2D). However, the same causes are major triggers of hypogonadism. Many T2D patients show low testosterone levels while hypogonadal men seem to be prone to become diabetic. Testosterone plays a major role in the regulation of muscle mass, adipose tissue, inflammation and insulin sensitivity and is therefore indirectly regulating several metabolic pathways, while T2D is commonly triggered by insulin resistance, increased adipose tissue and inflammation, showing a negative correlation between testosterone levels and T2D. Testosterone replacement therapy (TRT) is widely used in patients with symptoms of hypogonadism, however it is not commonly used as preventive intervention or treatment for T2D patients even though hypogonadal patients share many common symptoms (obesity, insulin insensitivity, increased inflammation, decrease in muscle mass and strength) with T2D patients. Even though TRT is often associated with side effects such as prostatic hypertrophy or cancer, cardiovascular risks due to increase in the number of red blood cells and infertility, several studies have shown that TRT remains a potent intervention improving metabolic functions such as glycated haemoglobin, blood sugar, total cholesterol and visceral fat. The purpose of this review is to discuss the possible benefits and risks of TRT in the prevention and treatment of obesity and T2D and assess the health risks and benefits of common T2D medications and testosterone.

Testosterone replacement therapy: For whom, when and how?

The finding of low circulating testosterone level in men is relatively frequent. The symptoms of hypogonadism are very frequent in the aging men. However, the diagnosis of hypogonadism is often neglected and the opportunity to replace low testosterone in older men is highly debated. The aim of this narrative review is to summarize the steps necessary to formulate a proper diagnosis and to guide toward an individualized treatment. While universally recognized the need to treat the young adults with known causes of pituitary or testicular failure, there are controversies on the cost-benefit of treating testosterone deficiency in older men. Discrepancies among the several available guidelines do not help to clarify the scenario, however, the recent larger clinical trials have shed some light on the fact that testosterone treatment carries some benefit, that is not free from risks. We provide an updated review of the diagnostic hallmarks, the several treatment modalities, with their advantages and disadvantages, and how to individualize and monitor treatment in order to maximize the benefits and minimize the risks. The treatment of male hypogonadism can no longer be downgraded and must become part of the cultural baggage of the endocrinologist.

The impact of testosterone replacement therapy on glycemic control, vascular function, and components of the metabolic syndrome in obese hypogonadal men with type 2 diabetes

OBJECTIVE

This study set out to assess effects of testosterone replacement therapy (TRT) on parameters of metabolic syndrome and vascular function in obese hypogonadal males with type 2 diabetes mellitus (DM2).

STUDY DESIGN

Fifty-five obese hypogonadal diabetic males on oral hypoglycemic treatment were enrolled into this one-year, double-blind, randomized, placebo-controlled clinical study. Group T (n = 28) was treated with testosterone undecanoate (1000 mg i.m. every 10 weeks) while group P (n = 27) received placebo.

METHODS

Anthropometrical and vascular measurements - flow-mediated dilatation (FMD) and intima media thickness (IMT) - biochemical and hormonal blood sample analyses were performed at the start of the study and after one year. Derived parameters (BMI, HOMA-IR, calculated free testosterone (cFT) and bioavailable testosterone (BT)) were calculated.

RESULTS

TRT resulted in reduction of HOMA-IR by 4.64 ± 4.25 (p < .001), HbA1c by 0.94 ± 0.88% points (p < .001), and an increase in FMD by 2.40 ± 4.16% points (p = .005).

CONCLUSION

TRT normalized serum testosterone levels, improved glycemic control and endothelial function while exerting no ill effects on the study population.

Sex differences in lipid and lipoprotein metabolism

BACKGROUND

Endogenous sex hormones are important for metabolic health in men and women. Before menopause, women are protected from atherosclerotic cardiovascular disease (ASCVD) relative to men. Women have fewer cardiovascular complications of obesity compared to men with obesity. Endogenous estrogens have been proposed as a mechanism that lessens ASCVD risk, as risk of glucose and lipid abnormalities increases when endogenous estrogens decline with menopause. While baseline risk is higher in males than females, endogenously produced androgens are also protective against fatty liver, diabetes and ASCVD, as risk goes up with androgen deprivation and with the decline in androgens with age.

SCOPE OF REVIEW

In this review, we discuss evidence of how endogenous sex hormones and hormone treatment approaches impact fatty acid, triglyceride, and cholesterol metabolism to influence metabolic and cardiovascular risk. We also discuss potential reasons for why treatment strategies with estrogens and androgens in older individuals fail to fully recapitulate the effects of endogenous sex hormones.

MAJOR CONCLUSIONS

The pathways that confer ASCVD protection for women are of potential therapeutic relevance. Despite protection relative to men, ASCVD is still the major cause of mortality in women. Additionally, diabetic women have similar ASCVD risk as diabetic men, suggesting that the presence of diabetes may offset the protective cardiovascular effects of being female through unknown mechanisms.

The complex association between metabolic syndrome and male hypogonadism

BACKGROUND

The complex association between metabolic syndrome (MetS) and male hypogonadism is well established. A number of observational studies show that low testosterone is associated with insulin resistance and an increased risk for diabetes mellitus and MetS in men.

AIMS

To elucidate the association between MetS and male hypogonadism, present epidemiological data on the co-existence of the two comorbidities, enlighten the underlying pathophysiology and appraise the effects of testosterone supplementation therapy (TTh) and lifestyle modifications on MetS and body composition in men.

MATERIALS AND METHODS

Systematic search to PubMed and Medline databases for publications reporting data on association between MetS and male hypogonadism.

RESULTS

Both MetS and male hypogonadism have a high prevalence in the general population and are frequently co-existing e.g. in males with diabetes. Accumulating evidence from animal and human studies suggests that MetS is involved in the pathogenesis of hypogonadism in males as well as the other way around. On the other hand, there is evidence for a favorable effect of testosterone supplementation in testosterone deficient men with MetS and/or diabetes mellitus.

CONCLUSIONS

Studies with superior methodological characteristics are needed in order to establish a role for testosterone supplementation in men with MetS and/or diabetes mellitus.

Estradiol Does Not Influence Lipid Measures and Inflammatory Markers in Testosterone-Clamped Healthy Men

Context

Experimentally controlled studies of estrogenic regulation of lipid measures and inflammatory cytokines in men are rare.

Objective

To delineate the effect of estradiol (E₂) on lipids and inflammatory markers.

Design

This was a placebo-controlled, single-masked, prospectively randomized study comprising experimentally degarelix-downregulated healthy men [n = 74; age 65 years (range, 57 to 77)] assigned to four treatment groups: (1) IM saline and oral placebo; (2) IM testosterone and oral placebo; (3) IM testosterone and oral anastrozole (aromatase inhibitor); and (4) IM testosterone, oral anastrozole, and transdermal E₂ for 22 (±1) days.

Results

Mean mass spectrometry–quantified serum E₂ concentrations ranged from 1.2 to 82 pg/mL in the four treatment groups. E₂ extremes did not alter total cholesterol, triglyceride, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein cholesterol (HDL-C) , non–HDL-C, apolipoprotein B, lipoprotein (a), IL-6, or high-sensitivity C-reactive protein (hsCRP) concentrations. Higher E₂ concentrations elevated both sex hormone-binding globulin and prolactin as positive controls. LDL cholesterol, adiponectin, and leptin were higher in hypogonadal subjects without testosterone or E₂ addback (P = 0.018, 0.039, and 0.023, respectively). Abdominal visceral fat area by CT (independent variable) correlated negatively with HDL-C (P = 0.017), and positively with triglycerides (P = 0.004), hsCRP (P = 0.005), and leptin (P < 0.0001).

Conclusion

In this placebo-controlled prospectively randomized study, wide variations in circulating E₂ did not influence lipid measures and inflammatory markers when testosterone concentrations were controlled experimentally. However, medically induced central hypogonadism in older men was accompanied by increased LDL cholesterol and metabolic cytokines, adiponectin and leptin. Abdominal visceral fat correlated strongly and positively with triglycerides, hsCRP, and leptin, but negatively with HDL.

Impact of Testosterone Deficiency and Testosterone Therapy on Lower Urinary Tract Symptoms in Men with Metabolic Syndrome

Lower urinary tract function is modulated by neural, vascular and urethral and bladder structural elements. The pathophysiological mechanisms of lower urinary tract symptoms (LUTS) encompass prostate enlargement, alterations in urethra histological structure bladder fibrosis and alterations in pelvic neuronal and vascular networks, The complex pathophysiological relationship between testosterone (T) deficiency (TD) and the constellations LUTS, and metabolic dysfunction manifested in the metabolic syndrome (Met S) remains poorly understood. TD has emerged as one the potential targets by which Met S may contribute to the onset and development as well as worsening of LUTS. Because it has been recognized that treatment of men with Met S with T therapy ameliorates Met S components, it is postulated that T therapy may represent a therapeutic target in improving LUTS. Furthermore, the effect of TD on the prostate remains unclear, and often debatable. It is believed that T exclusively promotes prostate growth, however recent evidence has strongly contradicted this belief. The true relationship between benign prostatic hyperplasia, TD, and LUTS remains elusive and further research will be required to clarify the role of T in both benign prostatic hypertrophy (BPH) and LUTS as a whole. Although there is conflicting evidence about the benefits of T therapy in men with BPH and LUTS, the current body of literature supports the safety of using this therapy in men with enlarged prostate. As the population afflicted with obesity epidemic continues to age, the number of men suffering from Met S and LUTS together is expected to increase.

Possible mechanisms underlying fatty liver in a rat model of male hypogonadism: A protective role for testosterone

AIMS

To investigate the effects of testosterone (Test) deficiency and testosterone replacement therapy (TRT) on the development of non-alcoholic fatty liver disease (NAFLD) and associated peripheral insulin resistance (IR) in male rats and to illustrate the underlying mechanisms of action.

MATERIALS AND METHODS

male Sprague Dawley rats were divided into 3 groups as follows: 1) sham-operated group (n = 11), 2) ORCD-induced group (n = 9) exposed to orchidectomy (ORCD), achieved by complete surgical removal of testicles, and 3) ORCD + Test treated group (n = 10) (11 ng/mL Test propionate, 3x/week, S.C.).

RESULTS

Data revealed significant increases in final body, liver, visceral and subcutaneous fats weights with significant increases in fasting plasma glucose and insulin levels and HOMA-IR. Additionally, ORCD rats had higher UAC for measured glucose levels and insulin levels during OGTT and higher AUC for measured glucose levels during ITT. Interesting, higher serum and hepatic levels of TGs and CHOL and higher serum levels of LDL were seen in ORCD-induced rats. Mechanistically, significant increases in mRNA levels of SREBP-1, SREBP-2, ACC-1, FAS, HMGCOAR and HMGCOAS with significant increases in protein levels of both precursor and mature SREBP-1 and SREBP-2, PPAR-α, p-PPAR-α, CPT-1 and UCP-2 and significant lower protein levels p-AMPK and p-ACC-1 were detected in livers of ORCD rats. Test administration to ORCD-induced rats significantly ameliorated all of the above mentioned biochemical endpoints and reversed the effect of ORCD on mRNA and protein levels of these targets. In conclusion, Test deficiency could be an independent risk factor for the development of NAFLD by upregulation of lipid synthesis and disturb fatty acids oxidation whereas Test therapy is a protective strategy.

Hypogonadotropic Hypogonadism in Men With Diabesity

One-third of men with obesity or type 2 diabetes have subnormal free testosterone concentrations. The lower free testosterone concentrations are observed in obese men at all ages, including adolescents at completion of puberty. The gonadotropin concentrations in these males are inappropriately normal; thus, these patients have hypogonadotropic hypogonadism (HH). The causative mechanism of diabesity-induced HH is yet to be defined but is likely multifactorial. Decreased insulin and leptin signaling in the central nervous system are probably significant contributors. Contrary to popular belief, estrogen concentrations are lower in men with HH. Men with diabesity and HH have more fat mass and are more insulin resistant than eugonadal men. In addition, they have a high prevalence of anemia and higher mortality rates than eugonadal men. Testosterone replacement therapy results in a loss of fat mass, gain in lean mass, and increase in insulin sensitivity in men with diabesity and HH. This is accompanied by an increase in insulin-signaling genes in adipose tissue and a reduction in inflammatory mediators that interfere with insulin signaling. There is also an improvement in sexual symptoms, anemia, LDL cholesterol, and lipoprotein (a). However, testosterone therapy does not consistently affect HbA_1c in men with diabetes. The effect of testosterone replacement on cardiovascular events or mortality in men with diabesity is not known and remains to be studied in prospective trials.

Insulin Sensitivity and Testicular Function in a Cohort of Adult Males Suspected of Being Insulin-Resistant

A cohort of 141 males (18–80 yo, 42.9 ± 12.9) strongly suspected of being Insulin Resistant (IR) was prospectively studied by determining their insulin sensitivity (Pancreatic Suppression Test, PST) and testicular function (total testosterone and SHBG). The subjects were labeled as IR when the Steady State Plasma Glucose (SSPG) was ≥150 mg/dL and Non-Insulin Resistant (NIR) when SSPG was <150 mg/dl; similarly, the subjects were labeled as Hypogonadal (HYPOG) when total testosterone was ≤3.0 ng/mL and Eugonadal (EUG) when total testosterone was >3.0 ng/mL. Two out of three subjects turned out to be IR, while around one in four subjects were HYPOG. Contingency analysis indicated a significant interdependence between insulin resistance and hypogonadism (chi-square was 4.69, p = 0.0303). Age (>43 yo) predicted hypogonadism (AUROC 0.606, p = 0.0308). Twice as many HYPOG subjects were IR as compared with EUG subjects. Also, HYPOG subjects exhibited higher SSPG values as compared with EUG subjects. Statistically, neither Weight nor BMI predicted hypogonadism, while Waist Circumference (>110 cm) was only a mediocre predictor (AUROC 0.640, p = 0.009). SSPG (>224 mg/dL) on the other hand, was the best predictor of hypogonadism (AUROC 0.709, p = 0.002), outperforming Waist Circumference (half of the subjects with an SSPG >224 mg/dL were HYPOG). Age did not predict insulin resistance, while Weight (>99 kg), BMI (>29), and especially, Waist Circumference (>99 cm, AUROC 0.812, p < 0.0001) were all predictors of insulin resistance. Almost 90% of the subjects with a waist circumference >99 cm was IR. As a logical consequence of the selection criteria (various clues suggesting insulin resistance), most subjects with normal weight in this cohort were IR (53.3%) while 20% were HYPOG. On the other hand, 13.6% of the obese subjects were NIR, and 2 out of 3 of them were both NIR and EUG. In conclusion, Waist Circumference predicted both insulin resistance (>99 cm) and hypogonadism (>110 cm), suggesting that the first hit of abdominal obesity is insulin resistance and the second hit is male hypogonadism. Normal weight did not protect from IR, while a relevant proportion of obese subjects were NIR (with 2/3 being also EUG).

Testosterone Therapy and Glucose Homeostasis in Men with Testosterone Deficiency (Hypogonadism)

Since the early 1990s, it has been recognized that testosterone (T) levels are lower in men with type 2 diabetes mellitus (T2DM) compared with nondiabetic men (controls). Hypogonadism has been reported in approximately 50% of men with T2DM with robust correlations with measures of obesity, such as waist circumference and body mass index (BMI). In longitudinal studies, hypogonadism has been identified as a predictor of incident T2DM. Experimental withdrawal of T led to acute decreased insulin sensitivity, which can be reversed by normalization of T concentrations. Androgen deprivation therapy, commonly used in men with advanced prostate cancer, increases the risk of incident T2DM significantly.While short-term studies of T therapy in hypogonadal men with T2DM show only minor effects, long-term administration of T leads to meaningful and sustained improvements of glycemic control with parallel reductions in body weight and waist circumference. The more insulin-resistant and obese a patient is at the time of initiation of T therapy, the more improvements are noted. The observed effects are likely mediated by the increase in lean body mass invariably achieved by T therapy, as well as the improvement in energy and motivation, referred to as the psychotropic effects of T. As recommended by various guidelines, measuring T levels and, if indicated, restoring men's T levels into the normal physiological range can have a substantial impact on ameliorating T2DM in hypogonadal men.

Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline

OBJECTIVE

To update the "Testosterone Therapy in Men With Androgen Deficiency Syndromes" guideline published in 2010.

PARTICIPANTS

The participants include an Endocrine Society-appointed task force of 10 medical content experts and a clinical practice guideline methodologist.

EVIDENCE

This evidence-based guideline was developed using the Grading of Recommendations, Assessment, Development, and Evaluation approach to describe the strength of recommendations and the quality of evidence. The task force commissioned two systematic reviews and used the best available evidence from other published systematic reviews and individual studies.

CONSENSUS PROCESS

One group meeting, several conference calls, and e-mail communications facilitated consensus development. Endocrine Society committees and members and the cosponsoring organization were invited to review and comment on preliminary drafts of the guideline.

CONCLUSIONS

We recommend making a diagnosis of hypogonadism only in men with symptoms and signs consistent with testosterone (T) deficiency and unequivocally and consistently low serum T concentrations. We recommend measuring fasting morning total T concentrations using an accurate and reliable assay as the initial diagnostic test. We recommend confirming the diagnosis by repeating the measurement of morning fasting total T concentrations. In men whose total T is near the lower limit of normal or who have a condition that alters sex hormone-binding globulin, we recommend obtaining a free T concentration using either equilibrium dialysis or estimating it using an accurate formula. In men determined to have androgen deficiency, we recommend additional diagnostic evaluation to ascertain the cause of androgen deficiency. We recommend T therapy for men with symptomatic T deficiency to induce and maintain secondary sex characteristics and correct symptoms of hypogonadism after discussing the potential benefits and risks of therapy and of monitoring therapy and involving the patient in decision making. We recommend against starting T therapy in patients who are planning fertility in the near term or have any of the following conditions: breast or prostate cancer, a palpable prostate nodule or induration, prostate-specific antigen level > 4 ng/mL, prostate-specific antigen > 3 ng/mL in men at increased risk of prostate cancer (e.g., African Americans and men with a first-degree relative with diagnosed prostate cancer) without further urological evaluation, elevated hematocrit, untreated severe obstructive sleep apnea, severe lower urinary tract symptoms, uncontrolled heart failure, myocardial infarction or stroke within the last 6 months, or thrombophilia. We suggest that when clinicians institute T therapy, they aim at achieving T concentrations in the mid-normal range during treatment with any of the approved formulations, taking into consideration patient preference, pharmacokinetics, formulation-specific adverse effects, treatment burden, and cost. Clinicians should monitor men receiving T therapy using a standardized plan that includes: evaluating symptoms, adverse effects, and compliance; measuring serum T and hematocrit concentrations; and evaluating prostate cancer risk during the first year after initiating T therapy.

Multiple Mechanisms Linking Type 2 Diabetes and Alzheimer's Disease: Testosterone as a Modifier

Evidence in support of links between type-2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) has increased considerably in recent years. AD pathological hallmarks include the accumulation of extracellular amyloid-β (Aβ) and intracellular hyperphosphorylated tau in the brain, which are hypothesized to promote inflammation, oxidative stress, and neuronal loss. T2DM exhibits many AD pathological features, including reduced brain insulin uptake, lipid dysregulation, inflammation, oxidative stress, and depression; T2DM has also been shown to increase AD risk, and with increasing age, the prevalence of both conditions increases. In addition, amylin deposition in the pancreas is more common in AD than in normal aging, and although there is no significant increase in cerebral Aβ deposition in T2DM, the extent of Aβ accumulation in AD correlates with T2DM duration. Given these similarities and correlations, there may be common underlying mechanism(s) that predispose to both T2DM and AD. In other studies, an age-related gradual loss of testosterone and an increase in testosterone resistance has been shown in men; low testosterone levels can also occur in women. In this review, we focus on the evidence for low testosterone levels contributing to an increased risk of T2DM and AD, and the potential of testosterone treatment in reducing this risk in both men and women. However, such testosterone treatment may need to be long-term, and would need regular monitoring to maintain testosterone at physiological levels. It is possible that a combination of testosterone therapy together with a healthy lifestyle approach, including improved diet and exercise, may significantly reduce AD risk.

Testosterone a key factor in gender related metabolic syndrome

Metabolic syndrome (MetS) is highly correlated with cardiovascular diseases. Although an excess of body fat is a determinant factor for MetS development, a reduced level of testosterone plays a fundamental role in its regulation. Low testosterone level is highly related to insulin resistance, visceral obesity and MetS. We have searched in Pubmed clinical trial with the password: testosterone and insulin resistance, and testosterone and MetS. We found 19 studies on the correlation between testosterone level with insulin resistance and 18 on the effect of testosterone therapy on MetS. A high correlation between low testosterone and insulin resistance has been found in men, but not in women. Testosterone administration in hypogonadal men improved MetS and reduced the mortality risk. Androgen and oestrogen receptors are expressed in adipocytes, muscle and liver tissue, and their activation is necessary to improve metabolic control. Normalization of testosterone level should be the primary treatment in men, along with caloric restriction and physical exercise. These findings come mainly from correlative data, and there remains a need for randomized trials to strengthen this evidence. This review will consider the effects of testosterone on the regulation and development of MetS in men and women.

Long-Term Testosterone Administration on Insulin Sensitivity in Older Men With Low or Low-Normal Testosterone Levels

Background

Serum testosterone levels and insulin sensitivity both decrease with age. Severe testosterone deficiency is associated with the development of insulin resistance. However, the effects of long-term testosterone administration on insulin sensitivity in older men with low or low-normal testosterone levels remain unknown.

Methods

The Testosterone Effects on Atherosclerosis in Aging Men Trial was a placebo-controlled, randomized, double-blind trial. The participants were 308 community-dwelling men, ≥60 years old, with total testosterone 100 to 400 ng/dL or free testosterone <50 pg/mL. A subset of 134 nondiabetic men (mean age, 66.7 ± 5.1 years) underwent an octreotide insulin suppression test at baseline and at 3 and 36 months after randomization to measure insulin sensitivity. Insulin sensitivity was estimated as the steady-state plasma glucose (SSPG) concentration at equilibrium during octreotide and insulin administration. Secondary outcomes included total lean mass (TLM) and total fat mass (TFM) by dual energy x-ray absorptiometry.

Results

There was a significant (P = 0.003) increase in SSPG in the placebo group, whereas no change was seen in testosterone-treated subjects from baseline to 36 months; however, the between-group differences in change in SSPG over 3 years were not statistically significant (+15.3 ± 6.9 mg/dL in the placebo group vs +6.2 ± 6.4 mg/dL in the testosterone group; mixed-model effect, P = 0.17). Changes in SSPG with testosterone treatment were not associated with changes in serum total or free testosterone concentrations. Changes in TFM but not TLM were associated with increases in SSPG. Stratification by age or baseline total testosterone level did not show significant intervention effects.

Conclusion

Testosterone administration for 36 months in older men with low or low-normal testosterone levels did not improve insulin sensitivity.

Effects of Honokiol on CYP450 Activity and Transporter mRNA Expression in Type 2 Diabetic Rats

This study was aimed to clarify the effect of honokiol (Hon) on the activity of Cytochrome P450 (CYP450) enzymes, and the level of mRNA expression of liver and kidney transporters in type 2 diabetic rats induced by high-fat diet and strepotozotocin. Rats were randomly divided into normal control (NC) group, diabetic control (DC) group and Hon groups (n = 6). The activities of hepatic CYP1A2, CYP2E1, CYP2C, CYP2B, CYP3A and CYP4A, and the mRNA expression levels of hepatic and renal transporters, were determined. Compared to the NC group, the activities of CYP1A2, CYP2E1, CYP4A and CYP2C in DC group were increased by 2.36-, 2.10-, 2.55- and 1.86-fold, respectively. The mRNA expression levels of hepatic Oat2, Oatp2b1 and Oatp1a5, and renal Oct1, Octn2, Oatp2b1 and Oatp1a5, were significantly down-regulated, while the mRNA expression levels of hepatic Octn2, Oatp3a1, Oatp1a1 and Mdr2, and renal Oat2, Mrp4 and Bcrp, were significantly upregulated. Compared to the DC group, Hon treatment significantly inhibited the activity of hepatic CYP2E1, CYP4A, 3A and CYP1A2 by 45.6%, 29.2%, 22.7% and 20.7% in Hon high dose group, respectively. Moreover, Hon treatment significantly inhibited the mRNA expression levels of renal Bcrp and Mrp4 by 2.63-fold and 1.54-fold, while significantly upregulated the mRNA expression levels of hepatic Oat2 and Oatp2b1 by 1.52-fold and 1.54-fold in Hon high dose group, respectively. The results suggested that under the diabetes condition, the changes of CYP450 activity and transporter expression inevitably interfere the normal transport, metabolism and efficacy of drugs. The present work firstly reported that Hon treatment ameliorated the abnormal change of hepatic CYP activity (including CYP2E1, CYP4A and CYP1A2) and the transporter mRNA expression (including hepatic Oat2 and Oatp2b1, renal Bcrp and Mrp4) in type 2 diabetic rats induced by high-fat diet and strepotozotocin, which are associated with the occurrence and development of diabetes.

Effects of testosterone supplement treatment in hypogonadal adult males with T2DM: a meta-analysis and systematic review

PURPOSE

Testosterone supplement treatment (TST) is a classic therapy for hypogonadal men with type 2 diabetes mellitus (T2DM), but the effects of TST in different studies are inconsistent. We conducted this meta-analysis to evaluate the precise role of TST in hypogonadal men with T2DM.

METHODS

PubMed, Embase, Cochrane Library and Web of Science were searched to identify qualified randomized controlled trials (RCTs). Pooled mean differences (MDs) with 95% confidence intervals (CIs) were calculated to measure the specific effects of TST. Trial sequential analysis was performed to verify the pooled results.

RESULTS

A total of eight RCTs were enrolled in our meta-analysis, including 596 hypogonadal participants with T2DM. Compared with comparators, TST can significantly improve glycemic control by reducing homeostatic model assessment of insulin resistance (MD - 0.79, 95% CI - 1.23 to - 0.34), fasting glucose (MD - 0.98, 95% CI - 1.13 to - 0.54), fasting insulin (MD - 2.47, 95% CI - 3.99 to - 0.95) and HbA1c% (MD - 0.45, 95% CI - 0.73 to - 0.16). In addition, TST can result in a decline in cholesterol (MD - 0.29, 95% CI - 0.38 to - 0.19) and triglyceride (MD - 0.37, 95% CI - 0.59 to - 0.15).

CONCLUSION

Our results indicated that TST can improve glycemic control and decrease TC and TG in hypogonadal patients with T2DM. We recommend TST during the anti-diabetic therapy in these patients.

Testosterone therapy for sexual dysfunction in men with Type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials

AIM

To evaluate the effectiveness of testosterone therapy on a range of sexual function domains in men with Type 2 diabetes.

METHOD

Electronic databases were searched for studies investigating the effect of testosterone therapy on sexual function in men with Type 2 diabetes. All randomized controlled trials were considered for inclusion if they compared the efficacy of testosterone therapy with that of placebo and reported sexual function outcomes. Statistical analysis was performed using a random-effects model, and heterogeneity was expressed using the I² statistic.

RESULTS

A total of 611 articles were screened. Six randomized control trials, in a total of 587 men with Type 2 diabetes, were eligible for inclusion. The pooled data suggested that testosterone therapy improves sexual desire (random-effects pooled effect size 0.314; 95% CI 0.082-0.546) and erectile function (random-effects pooled effect size 0.203; 95% CI 0.007-0.399) when compared with control groups. Testosterone therapy had no significant effect on constitutional symptoms or other sexual domains compared with control groups. No studies have investigated the incidence of prostate cancer, fertility and cardiovascular disease after testosterone therapy in men with Type 2 diabetes.

CONCLUSION

Testosterone therapy may moderately improve sexual desire and erectile function in men with Type 2 diabetes; however, available data are limited, and the long-term risks of testosterone therapy are not known in this specific patient group. We conclude that testosterone therapy is a potential treatment for men with Type 2 diabetes non-responsive to phosphodiesterase-5 inhibitors. Testosterone therapy could be considered for men with Type 2 diabetes when potential risks and benefits of therapy are carefully considered and other therapeutic options are unsuitable.

The Effect of Testosterone on Cardiovascular Biomarkers in the Testosterone Trials

CONTEXT

Studies of the possible cardiovascular risk of testosterone treatment are inconclusive.

OBJECTIVE

To determine the effect of testosterone treatment on cardiovascular biomarkers in older men with low testosterone.

DESIGN

Double-blind, placebo-controlled trial.

SETTING

Twelve academic medical centers in the United States.

PARTICIPANTS

In all, 788 men ≥65 years old with an average of two serum testosterone levels <275 ng/dL who were enrolled in The Testosterone Trials.

INTERVENTION

Testosterone gel, the dose adjusted to maintain the testosterone level in the normal range for young men, or placebo gel for 12 months.

MAIN OUTCOME MEASURES

Serum markers of cardiovascular risk, including lipids and markers of glucose metabolism, fibrinolysis, inflammation, and myocardial damage.

RESULTS

Compared with placebo, testosterone treatment significantly decreased total cholesterol (adjusted mean difference, -6.1 mg/dL; P < 0.001), high-density lipoprotein cholesterol (adjusted mean difference, -2.0 mg/dL; P < 0.001), and low-density lipoprotein cholesterol (adjusted mean difference, -2.3 mg/dL; P = 0.051) from baseline to month 12. Testosterone also slightly but significantly decreased fasting insulin (adjusted mean difference, -1.7 µIU/mL; P = 0.02) and homeostatic model assessment‒insulin resistance (adjusted mean difference, -0.6; P = 0.03). Testosterone did not change triglycerides, d-dimer, C-reactive protein, interleukin 6, troponin, glucose, or hemoglobin A1c levels more than placebo.

CONCLUSIONS AND RELEVANCE

Testosterone treatment of 1 year in older men with low testosterone was associated with small reductions in cholesterol and insulin but not with other glucose markers, markers of inflammation or fibrinolysis, or troponin. The clinical importance of these findings is unclear and requires a larger trial of clinical outcomes.

The role of hormones in muscle hypertrophy

Anabolic-androgenic steroids (AAS) and other hormones such as growth hormone (GH) and insulin-like growth factor-1 (IGF-1) have been shown to increase muscle mass in patients suffering from various diseases related to muscle atrophy. Despite known side-effects associated with supraphysiologic doses of such drugs, their anabolic effects have led to their widespread use and abuse by bodybuilders and athletes such as strength athletes seeking to improve performance and muscle mass. On the other hand, resistance training (RT) has also been shown to induce significant endogenous hormonal (testosterone (T), GH, IGF-1) elevations. Therefore, some bodybuilders employ RT protocols designed to elevate hormonal levels in order to maximize anabolic responses. In this article, we reviewed current RT protocol outcomes with and without performance enhancing drug usage. Acute RT-induced hormonal elevations seem not to be directly correlated with muscle growth. On the other hand, supplementation with AAS and other hormones might lead to supraphysiological muscle hypertrophy, especially when different compounds are combined.

Testosterone and the Heart

Testosterone (T) has a number of important effects on the cardiovascular system. In men, T levels begin to decrease after age 40, and this decrease has been associated with an increase in all-cause mortality and cardiovascular (CV) risk. Low T levels in men may increase their risk of developing coronary artery disease (CAD), metabolic syndrome, and type 2 diabetes. Reduced T levels in men with congestive heart failure (CHF) portends a poor prognosis and is associated with increased mortality. Studies have reported a reduced CV risk with higher endogenous T concentration, improvement of known CV risk factors with T therapy, and reduced mortality in T-deficient men who underwent T replacement therapy versus untreated men. Testosterone replacement therapy (TRT) has been shown to improve myocardial ischemia in men with CAD, improve exercise capacity in patients with CHF, and improve serum glucose levels, HbA1c, and insulin resistance in men with diabetes and prediabetes. There are no large long-term, placebo-controlled, randomized clinical trials to provide definitive conclusions about TRT and CV risk. However, there currently is no credible evidence that T therapy increases CV risk and substantial evidence that it does not. In fact, existing data suggests that T therapy may offer CV benefits to men.

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.

Testosterone level and risk of type 2 diabetes in men: a systematic review and meta-analysis

BACKGROUND

Type 2 diabetes is a risk factor for testosterone deficiency and impaired sex steroid status. Some studies also investigated the association of testosterone level with diabetes risk in men, but reported controversial findings. To clarify this issue, we conducted a systematic review and meta-analysis.

METHODS

PubMed, EMBASE and Web of Science were searched for eligible cohort or nested case-control studies published up to August 15, 2017. Meta-analysis was used to calculate the pooled relative risk (RR) of type 2 diabetes associated with higher testosterone level.

RESULTS

Thirteen cohort or nested case-control studies with 16,709 participants were included. Meta-analysis showed that higher total testosterone level could significantly decrease the risk of type 2 diabetes in men (RR = 0.65; 95% CI 0.50-0.84; P = 0.001), and higher free testosterone level could also decrease the risk of type 2 diabetes in men (RR = 0.94; 95% CI 0.90-0.99; P = 0.014). After excluding two studies that did not calculate RRs by quartiles of testosterone levels, both higher total testosterone and free testosterone levels could decrease the risk of type 2 diabetes in men, and the pooled RRs were 0.62 (95% CI 0.51-0.76; P < 0.001) and 0.77 (95% CI 0.61-0.98; P = 0.03), respectively.

CONCLUSION

This meta-analysis suggests that higher testosterone level can significantly decrease the risk of type 2 diabetes in men. Therefore, combined with previous researches, the findings above suggest a reverse-causality scenario in the relation between testosterone deficiency and risk of type 2 diabetes in men.

Cholesterol metabolism and Cx43, Cx46, and Cx50 gap junction protein expression and localization in normal and diabetic and obese ob/ob and db/db mouse testes

Decreased fertility and birth rates arise from metabolic disorders. This study assesses cholesterol metabolism and Cx46, Cx50, and Cx43 expression in interstitium- and seminiferous tubule-enriched fractions of leptin-deficient ( ob/ob) and leptin receptor-deficient ( db/db) mice, two type 2 diabetes and obesity models associated with infertility. Testosterone levels decreased and glucose and free and esterified cholesterol (FC and EC) levels increased in serum, whereas FC and EC levels decreased in the interstitium, in ob/ob and db/db mice. In tubules, a decrease in EC caused FC-to-EC ratios to increase in db/db mice. In tubules, only acyl coenzyme A:cholesterol acyl transferase type 1 and 2 protein levels significantly decreased in ob/ob, but not db/db, mice compared with wild-type mice, and imbalances in the cholesterol transporters Niemann-Pick C1 (NPC1), ATP-binding cassette A1 (ABCA1), scavenger receptor class B member I (SR-BI), and cluster of differentiation 36 (CD36) were observed in ob/ob and db/db mice. In tubules, 14-kDa Cx46 prevailed during development, 48- to 49- and 68- to 71-kDa Cx46 prevailed during adulthood, and total Cx46 changed little. Compared with wild-type mice, 14-kDa Cx46 increased, whereas 48- to 49- and 68- to 71-kDa Cx46 decreased, in tubules, whereas the opposite occurred in the interstitium, in db/db and ob/ob mice. Total and 51-kDa Cx50 increased in db/db and ob/ob interstitium and tubules. Cx43 levels decreased in ob/ob interstitium and tubules, whereas Cx43 decreased in db/db interstitium but increased in db/db tubules. Apoptosis levels measured by ELISA and numbers of apostain-labeled apoptotic cells significantly increased in db/db, but not ob/ob, tubules. Testicular db/db capillaries were Cx50-positive but weakly Cx43-positive with a thickened lamina, suggesting altered permeability. Our findings indicate that the db mutation-induced impairment of meiosis may arise from imbalances in cholesterol metabolism and upregulated Cx43 expression and phosphorylation in tubules.

Guidelines for the Diagnosis and Treatment of testosterone deficiency (hypogonadism) in male patients with diabetes mellitus

Hypogonadism in men, defined as a reduction in serum testosterone in combination with characteristic symptoms and/or signs (described in detail later), is common in diabetes mellitus (DM). These recommendations do not cover the whole range of pathologies that cause the development of testosterone deficiency (hypogonadism), but focus on its clinical variants and characteristic for men with diabetes. The recommendations provide data on the prevalence of hypogonadism in diabetes, its etiology. In the section "diagnostics" the features of anamnesis of patients with hypogonadism with diabetes, the necessary methods of physical and laboratory examination are presented in detail. The risk factors and clinical consequences of hypogonadism are separately examined. In the section "choice of treatment methods", there are possible treatment options for such patients using various androgenic therapies, taking into account the needs of the man, maintaining his reproductive function and risk factors. Particular attention is paid to indications, contraindications and risk factors for androgen therapy in men with diabetes, especially in old age. With this in mind, principles for monitoring the treatment are developed. Based on a large number of studies, favorable effects of androgen replacement therapy in men with hypogonadism and diabetes have been demonstrated.

Endocrine Disrupting Chemicals Mediated through Binding Androgen Receptor Are Associated with Diabetes Mellitus

Endocrine disrupting chemicals (EDCs) can mimic natural hormone to interact with receptors in the endocrine system and thus disrupt the functions of the endocrine system, raising concerns on the public health. In addition to disruption of the endocrine system, some EDCs have been found associated with many diseases such as breast cancer, prostate cancer, infertility, asthma, stroke, Alzheimer’s disease, obesity, and diabetes mellitus. EDCs that binding androgen receptor have been reported associated with diabetes mellitus in in vitro, animal, and clinical studies. In this review, we summarize the structural basis and interactions between androgen receptor and EDCs as well as the associations of various types of diabetes mellitus with the EDCs mediated through androgen receptor binding. We also discuss the perspective research for further understanding the impact and mechanisms of EDCs on the risk of diabetes mellitus.

Testosterone is protective against impaired glucose metabolism in male intrauterine growth-restricted offspring

Placental insufficiency alters the intrauterine environment leading to increased risk for chronic disease including impaired glucose metabolism in low birth weight infants. Using a rat model of low birth weight, we previously reported that placental insufficiency induces a significant increase in circulating testosterone in male intrauterine growth-restricted offspring (mIUGR) in early adulthood that is lost by 12 months of age. Numerous studies indicate testosterone has a positive effect on glucose metabolism in men. Female growth-restricted littermates exhibit glucose intolerance at 6 months of age. Thus, the aim of this paper was to determine whether mIUGR develop impaired glucose metabolism, and whether a decrease in elevated testosterone levels plays a role in its onset. Male growth-restricted offspring were studied at 6 and 12 months of age. No impairment in glucose tolerance was observed at 6 months of age when mIUGR exhibited a 2-fold higher testosterone level compared to age-matched control. Fasting blood glucose was significantly higher and glucose tolerance was impaired with a significant decrease in circulating testosterone in mIUGR at 12 compared with 6 months of age. Castration did not additionally impair fasting blood glucose or glucose tolerance in mIUGR at 12 months of age, but fasting blood glucose was significantly elevated in castrated controls. Restoration of elevated testosterone levels significantly reduced fasting blood glucose and improved glucose tolerance in mIUGR. Thus, our findings suggest that the endogenous increase in circulating testosterone in mIUGR is protective against impaired glucose homeostasis.

Benefits and Health Implications of Testosterone Therapy in Men With Testosterone Deficiency

INTRODUCTION

Testosterone (T) deficiency (TD; hypogonadism) has deleterious effects on men's health; negatively affects glycometabolic and cardiometabolic functions, body composition, and bone mineral density; contributes to anemia and sexual dysfunction; and lowers quality of life. T therapy (TTh) has been used for the past 8 decades to treat TD, with positive effects on signs and symptoms of TD.

AIM

To summarize the health benefits of TTh in men with TD.

METHODS

A comprehensive literature search was carried out using PubMed, articles relevant to TTh were accessed and evaluated, and a comprehensive summary was synthesized.

MAIN OUTCOME MEASURES

Improvements in signs and symptoms of TD reported in observational studies, registries, clinical trials, and meta-analyses were reviewed and summarized.

RESULTS

A large body of evidence provides significant valuable information pertaining to the therapeutic value of TTh in men with TD. TTh in men with TD provides real health benefits for bone mineral density, anemia, sexual function, glycometabolic and cardiometabolic function, and improvements in body composition, anthropometric parameters, and quality of life.

CONCLUSION

TTh in the physiologic range for men with TD is a safe and effective therapeutic modality and imparts great benefits on men's health and quality of life. Traish AM. Benefits and Health Implications of Testosterone Therapy in Men With Testosterone Deficiency. Sex Med Rev 2018;6:86-105.

Effects of testosterone supplementation therapy on lipid metabolism in hypogonadal men with T2DM: a meta-analysis of randomized controlled trials

Testosterone supplementation may be effective for the treatment of hypogonadism in men with type 2 diabetes mellitus (T2DM), but the evidence from randomized controlled trials (RCTs) is inconclusive. We aimed to systematically summarize results from intervention studies and assess the effects of testosterone supplementation therapy (TST) on lipid metabolism in RCTs of hypogonadal men with T2DM by meta-analysis. PubMed, Embase, and Cochrane Library databases were searched for studies reporting the effect of TST on lipid metabolism in hypogonadal men with T2DM until December 31, 2016. Seven RCTs from 252 trials, enrolling a total of 612 patients in the experimental and control groups with a mean age of 58.5 years, were included in this study. The pooled results of the meta-analysis demonstrated that TST significantly decreased TC and TG levels in hypogonadal men with T2DM compared with the control group, with mean differences (MDs) of -6.44 (95% CI: -11.82 to -1.06; I²  = 28%; p = 0.02) and -27.94 (95% CI: -52.33 to -3.54; I²  = 76%; p = 0.02). Subgroup analyses revealed that the heterogeneity (I²  = 76%) of TG originated from different economic regions, in which economic development, genetic and environmental factors, and dietary habits affect lipid metabolism of human, with a decrease (I²  = 45%) in developed countries. Additionally, subgroup analyses showed that TST increased HDL-C level in developing countries compared with the control group (MD = 2.79; 95% CI: 0.73 to 4.86; I²  = 0%; p = 0.008), but there was no improvement in developed countries (MD = 1.02; 95% CI: -4.55 to 6.60; I²  = 91%; p = 0.72). However, LDL-C levels were not improved consistently. Because the relationship between lipid metabolism and atherosclerosis is unequivocal, TST, which ameliorates lipid metabolism, may decrease the morbidity and mortality of cardiovascular disease in hypogonadal men with T2DM by preventing atherogenesis.

MECHANISMS IN ENDOCRINOLOGY: The sexually dimorphic role of androgens in human metabolic disease

Female androgen excess and male androgen deficiency manifest with an overlapping adverse metabolic phenotype, including abdominal obesity, insulin resistance, type 2 diabetes mellitus, non-alcoholic fatty liver disease and an increased risk of cardiovascular disease. Here, we review the impact of androgens on metabolic target tissues in an attempt to unravel the complex mechanistic links with metabolic dysfunction; we also evaluate clinical studies examining the associations between metabolic disease and disorders of androgen metabolism in men and women. We conceptualise that an equilibrium between androgen effects on adipose tissue and skeletal muscle underpins the metabolic phenotype observed in female androgen excess and male androgen deficiency. Androgens induce adipose tissue dysfunction, with effects on lipid metabolism, insulin resistance and fat mass expansion, while anabolic effects on skeletal muscle may confer metabolic benefits. We hypothesise that serum androgen concentrations observed in female androgen excess and male hypogonadism are metabolically disadvantageous, promoting adipose and liver lipid accumulation, central fat mass expansion and insulin resistance.

Effects of 8-Year Treatment of Long-Acting Testosterone Undecanoate on Metabolic Parameters, Urinary Symptoms, Bone Mineral Density, and Sexual Function in Men With Late-Onset Hypogonadism

INTRODUCTION

The long-term effects of long-acting testosterone undecanoate (TU) and androgen receptor CAG repeat lengths in Thai men with late-onset hypogonadism (LOH) have not been reported.

AIM

To analyze the 8-year follow-up effects of intramuscular TU therapy on metabolic parameters, urinary symptoms, bone mineral density, and sexual function and investigate CAG repeat lengths in men with LOH.

METHODS

We reviewed the medical records of 428 men with LOH who had been treated with TU and 5 patients were diagnosed with prostate cancer during TU therapy. There were 120 patients (mean age = 65.6 ± 8.9 years) who had 5 to 8 years of continuous TU supplementation and sufficiently completed records for analysis. Genomic DNA was extracted from peripheral blood and the CAG repeat region was amplified by polymerase chain reaction. Fragment analysis, sequencing, electropherography, and chromatography were performed.

MAIN OUTCOME MEASURES

The main outcome measure was dynamic parameter changes during testosterone supplementation.

RESULTS

TU did not improve all obesity parameters. A statistically significant decrease was found in waist circumference, percentage of body fat, glycated hemoglobin, cholesterol, low-density lipoprotein, and International Prostate Symptom Score (P < .05). TU did not produce differences in body mass index, high-density lipoprotein, triglyceride, or the Aging Male Symptoms score from baseline. However, a statistically significant increase was found in the level of testosterone, prostate-specific antigen, hematocrit, International Index of Erectile Function score, and vertebral and femoral bone mineral density (P < .05). No major adverse cardiovascular events or prostate cancer occurred during this study. The CAG repeat length was 14 to 28 and the median CAG length was 22. There was no association between CAG repeat length and any of the anthropometric measurements.

CONCLUSION

Long-term TU treatment in men with LOH for up to 8 years appears to be safe, tolerable, and effective in correcting obesity parameters.

Clinical significance of androgen secretion disorders in men with a malignancy

Cancer and its treatment can lead in men to testosterone deficiency, accompanied by somatic and mental symptoms. Germ cell tumours and their treatment may disturb the pituitary-gonadal axis, hence leading to significant clinical abnormalities. In some prostate cancer patients, castration, temporary or permanent, is a desired therapeutic condition. Yet, it is burdened with various side effects of complex intensity and significance. Last but not least, patients in the terminal stage of a malignancy present with low testosterone concentrations as a part of anorexia-cachexia syndrome. Oncological management of such patients disturbs their homeostasis, androgen metabolism included, which results in numerous complications and worsens their quality of life. In the present paper, we analysed the frequency and sequelae of testosterone deficiency in some clinical scenarios, on the basis of original papers, meta-analyses and reviews available in PubMed. Androgen secretion disorders in male cancer patients depend on a cancer type, stage and methods of treatment. Number of testicular cancer survivors is increasing, and as a consequence, more patients cope with late complications, testosterone deficiency included. Hormone therapy in prostate cancer patients significantly prolongs survival, and then numerous men experience long-term adverse effects of androgen deficiency. Those, in turn, particularly the metabolic syndrome, may contribute to increased mortality. Androgen deficiency is a part of cancer anorexia-cachexia syndrome. The role of androgen deficiency in cancer patients is still under debate, and further studies are urgently needed to establish appropriate clinical guidelines.

Testosterone improves the differentiation efficiency of insulin-producing cells from human induced pluripotent stem cells

Human induced pluripotent stem cells (hiPSCs) may provide potential resource for regenerative medicine research, including generation of insulin-producing cells for diabetes research and insulin production. Testosterone (T) is an androgen hormone which promotes protein synthesis and improves the management of type 2 diabetes in clinical studies. Concurrently, co-existed hyperandrogenism and hyperinsulinism is frequently observed in polycystic ovary syndrome, congenital adrenal hyperplasia and some of Wermer's syndrome. However, the relationship among androgens, insulin and the differentiation of pancreatic β cells is still not fully clear. Here we find that T improves the differentiation efficiency of insulin-producing cells from hiPSCs. The addition of T into routine differentiation formula for pancreatic β cells increases the differentiation efficiency from 12% to 35%. The administration of T promotes the expression of key genes associated with β cells differentiation including NGN3, NEUROD1 and INS. This finding benefits the ongoing process to optimize the differentiation protocol of pancreatic β cells from hiPSCs, and provides some degree of understanding the clinical management of T for type 2 diabetes.

Is there a protective role of testosterone against high-grade prostate cancer? Incidence and severity of prostate cancer in 553 patients who underwent prostate biopsy: a prospective data register

This study investigated the role of testosterone replacement therapy (TRT) in prostate safety and cancer progression. A cohort of 553 patients, 42 treated and 162 untreated hypogonadal men, and 349 eugonadal men were included. Pathological analysis of prostate biopsies examining the incidence and severity of PCa revealed that: 16.7% of treated hypogonadal men had a positive biopsy, a Gleason score of ≤6 in 71.4% and >6 in 28.6% of men, a predominant score of 3 and tumour staging of II in 85.7% men; 51.9% of untreated hypogonadal men had a positive biopsy, a Gleason score of ≤6 in 40.5% and >6 in 59.5% men, a predominant score of 3 (77.4%) and tumour staging of II (41.7%) or III (40.5%); 37.8% of eugonadal men had a positive biopsy, a Gleason score of ≤6 in 42.4% and >6 in 57.6% of men, a predominant score of 3 (82.6%) and tumour staging of II (44.7%) or III (47.7%). The incidence of positive prostate biopsies was lowest in hypogonadal men receiving TRT, with significantly lower severity of PCa in terms of staging and grading in the same group. These results suggest that TRT might have a protective effect against high-grade PCa.

Normalization of Testosterone Levels After Testosterone Replacement Therapy Is Not Associated With Reduced Myocardial Infarction in Smokers

Objective

To examine the effect of cigarette smoking (CS) status and total testosterone (TT) levels after testosterone replacement therapy (TRT) on all-cause mortality, myocardial infarction (MI), and stroke in male smokers and nonsmokers without history of MI and stroke.

Participants and Methods

Data from 18,055 males with known CS status and low TT levels who received TRT at the Veterans Health Administration between December 1, 1999, and May 31, 2014, were grouped into (1) current smokers with normalized TT, (2) current smokers with nonnormalized TT, (3) nonsmokers with normalized TT, and (4) nonsmokers with nonnormalized TT. Combined effect of CS status and TT level normalization after TRT on all-cause mortality, MI, and stroke was compared using propensity score–weighted Cox proportional hazard models.

Results

Normalization of serum TT levels in nonsmokers was associated with a significant decrease in all-cause mortality (hazard ratio [HR]=0.526; 95% CI, 0.477-0.581; P<.001) and MI (HR=0.717; 95% CI, 0.522-0.986; P<.001). Among current smokers, normalization of serum TT levels was associated with a significant decrease in only all-cause mortality (HR=0.563; 95% CI, 0.488-0.649; P<.001) without benefit in MI (HR=1.096; 95% CI, 0.698-1.720; P=.69). Importantly, compared with nonsmokers with normalized TT, all-cause mortality (HR=1.242; 95% CI, 1.104-1.396; P<.001), MI (HR=1.706; 95% CI, 1.242-2.342; P=.001), and stroke (HR=1.590; 95% CI, 1.013-2.495; P=.04) were significantly higher in current smokers with normalized TT.

Conclusion

We conclude that active CS may negate the protective effect of testosterone level normalization on all-cause mortality and MI after TRT.