Treatment of hypogonadism with testosterone in patients with type 2 diabetes mellitus

Cardiovascular safety of testosterone replacement therapy in men: an updated systematic review and meta-analysis

INTRODUCTION

The cardiovascular (CV) safety of testosterone (T) replacement therapy (TRT) is still conflicting. Recent data suggested a TRT-related increased risk of atrial fibrillation (AF). The aim of this study was to systematic review and meta-analyze CV risk related to TRT as derived from placebo controlled randomized trials (RCTs).

AREAS COVERED

An extensive Medline, Embase, and Cochrane search was performed. All placebo-controlled RCTs reporting data on TRT-related CV safety were considered. To better analyze the role of T on AF, population-based studies investigating the relationship between endogenous circulating T levels and AF incidence were also included and analyzed.

EXPERT OPINION

Out of 3.615, 106 studies were considered, including 8.126 subjects treated with TRT and 7.310 patients allocated to placebo. No difference between TRT and placebo was observed when major adverse CV events were considered. Whereas the incidence of non-fatal arrhythmias and AF was increased in the only trial considering CV safety as the primary endpoint, this was not confirmed when all other studies were considered (MH-OR 1.61[0.84;3.08] and 1.44[0.46;4.46]). Similarly, no relationship between endogenous T levels and AF incidence was observed after the adjustment for confounders Available data confirm that TRT is safe and it is not related to an increased CV risk.

Ameliorative effect of Stevia rebaudiana Bertoni on sperm parameters, in vitro fertilization, and early embryo development in a streptozotocin-induced mouse model of diabetes

Diabetes mellitus (DM) is a common metabolic disease characterized by high blood sugar levels. It is well known that men with diabetes frequently experience reproductive disorders and sexual dysfunction. In fact, sperm quality has a significant effect on fertilization success and embryo development. The current study aimed to investigate the effect of Stevia rebaudiana hydroalcoholic extract on serum testosterone levels, sperm parameters, in vitro fertilization (IVF) success, and in vitro embryonic developmental potential to reach the blastocyst stage in a streptozotocin (STZ)-induced mouse model of diabetes. In this research, 30 male mice were distributed randomly into control, diabetic (streptozotocin 150 mg/kg) and diabetic + Stevia (400 mg/kg) groups. The results revealed a decrease in body and testis weight and elevated blood fasting blood sugar (FBS) levels in the diabetic group, compared with the control. However, Stevia treatment significantly increased body and testis weight, while serum FBS levels were decreased compared with the diabetic group. In addition, Stevia significantly increased blood testosterone levels compared with the diabetic group. Moreover, sperm parameters were improved considerably by Stevia treatment compared with the diabetic group. Furthermore, Stevia administration significantly promoted IVF success rate and in vitro development of fertilized oocytes compared with the diabetic group. In summary, our data indicated that Stevia enhanced sperm parameters, IVF success, and in vitro embryonic developmental competency in diabetic mice, probably because of its antioxidant effects. Therefore, Stevia could ameliorate sperm parameters that, in turn, increase fertilization outcomes in experimental-induced diabetes.

Treatment with Testosterone Therapy in Type 2 Diabetic Hypogonadal Adult Males: A Systematic Review and Meta-Analysis

Testosterone replacement therapy (TRT) has been used to treat hypogonadal males with type 2 diabetes mellitus (T2DM) for a long time, despite variable results. This meta-analysis examines TRT's role in hypogonadal males with T2DM. The databases PubMed, Embase, and Google Scholar were searched for relevant RCTs and observational studies. Estimated pooled mean differences (MDs) and relative risks with 95% confidence intervals were used to measure the effects of TRT (CIs). When compared to the placebo, TRT improves glycemic management by significantly reducing glycated hemoglobin (HBA1c) levels (WMD = -0.29 [-0.57, -0.02] p = 0.04; I2 = 89.8%). Additionally, it reduces the homeostatic model assessment levels of insulin resistance (WMD = -1.47 [-3.14, 0.19]; p = 0.08; I2 = 56.3%), fasting glucose (WMD = -0.30 [-0.75, 0.15]; p = 0.19; I2 = 84.4%), and fasting insulin (WMD = -2.95 [-8.64, 2.74]; however, these results are non-significant. On the other hand, HBA1c levels are significantly reduced with TRT; in addition, total testosterone levels significantly increase with testosterone replacement therapy (WMD = 4.51 [2.40, 6.61] p = 0.0001; I2 = 96.3%). Based on our results, we hypothesize that TRT can improve glycemic control and hormone levels, as well as lower total cholesterol, triglyceride, and LDL cholesterol levels while raising HDL cholesterol in hypogonadal type 2 diabetes patients. To this end, we recommend TRT for these patients in addition to standard diabetes care.

Adult- and late-onset male hypogonadism: the clinical practice guidelines of the Italian Society of Andrology and Sexual Medicine (SIAMS) and the Italian Society of Endocrinology (SIE)

PURPOSE

To provide the evidence-based recommendations on the role of testosterone (T) on age-related symptoms and signs remains.

METHODS

The Italian Society of Andrology and Sexual Medicine (SIAMS) and the and the Italian Society of Endocrinology (SIE) commissioned an expert task force to provide an updated guideline on adult-onset male hypogonadism. Derived recommendations were based on Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system.

RESULTS

Clinical diagnosis of adult-onset hypogonadism should be based on a combination of clinical and biochemical parameters. Testosterone replacement therapy (TRT) should be offered to all symptomatic subjects with hypogonadism after the exclusion of possible contraindications. T gels and the long-acting injectable T are currently available preparations showing the best efficacy/safety profile. TRT can improve all aspects of sexual function, although its effect is limited in more complicated patients. Body composition (reducing fat mass and increasing lean mass) is improved after TRT, either in subjects with or without metabolic syndrome or type 2 diabetes. Conversely, the role of TRT in improving glycometabolic control is more conflicting. TRT can result in increasing bone mineral density, particularly at lumbar site, but no information on fracture risk is available. Limited data support the use of TRT for improving other outcomes, including mood frailty and mobility.

CONCLUSIONS

TRT can improve sexual function and body composition particularly in less complicated adult and in aging subjects with hypogonadism. When hypogonadism is adequately diagnosed, T appropriately prescribed and subjects correctly followed up, no short-term increased risk of adverse events is observed. Longer and larger studies are advisable to better clarify TRT long-term efficacy/safety profile.

Effects of androgens on glucose metabolism

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

Effects of testosterone therapy in adult males with hypogonadism and T2DM: A meta-analysis and systematic review

BACKGROUND AND AIMS

Testosterone supplementation therapy (TST) is a longstanding treatment for hypogonadal men with type 2 diabetes mellitus (T2DM), even though the benefits of TST are variable among trials. This meta-analysis was done to determine the specific role of TST in hypogonadal men with T2DM.

METHODS

PubMed, Embase, and Google Scholar were queried to discover eligible randomized controlled trials (RCTs) and observational studies. To quantify the specific effects of TST, we estimated pooled mean differences (MDs) and relative risks with 95% confidence intervals (CIs).

RESULTS

Our meta-analysis included 1596 hypogonadal T2DM subjects from 12 randomized controlled trials and one observational study. TST can significantly enhance glycemic control compared to placebo by decreasing homeostatic model assessment of insulin resistance (WMD = -1.55 [-2.65, -0.45]; p = 0.26; I2 = 20.2%), fasting glucose (WMD = -0.35 [-0.79, 0.10]; p = 0.07; I2 = 69.7%), fasting insulin (WMD = -2.88 [-6.12, 0.36]; p = In addition, TST can decrease cholesterol (WMD = -0.28 [-0.47, -0.09] p = 0.0008; I2 = 91%) and triglyceride (WMD = -0.23 [-0.43, -0.03] p = 0.03; I2 = 79.2%). Furthermore, Testosterone therapy is related to a significant rise in total testosterone levels (WMD = 5.08 [2.90, 7.26] p = 0.0002; I2 = 92.9%). Pooling of free testosterone levels indicated a larger increase in the patients who got TST than placebo (WMD = 81.21 [23.87, 138.54] p = 0.07; I2 = 70%).

CONCLUSION

Our findings suggested that TST can enhance glycemic control and hormone levels and reduce total cholesterol, triglyceride, LDL cholesterol whereas increase HDL cholesterol in hypogonadal T2DM patients. Therefore, in these patients, we propose TST alongside anti-diabetic treatment.

Morbidity and mortality in men: Role of androgens

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

Baseline Testosterone Predicts Body Composition and Metabolic Response to Testosterone Therapy

CONTEXT

Male hypogonadism adversely affects body composition, bone mineral density (BMD), and metabolic health. A previous report showed that pre-treatment testosterone (T) levels of <200 ng/dl is associated with greater improvement in spine BMD with T therapy. However, to date, there is no study that investigates whether baseline T levels also influence body composition and metabolic response to T therapy.

OBJECTIVE

The aim of this study is to determine if there are differences in the changes in body composition, metabolic profile, and bone turnover markers, in addition to BMD, in response to T therapy in men with a baseline T level of <264 ng/dl compared to those with levels ≥264 ng/dl.

METHODS

This is a secondary analysis of a single-arm, open-label clinical trial (NCT01378299) on pharmacogenetics of response to T therapy conducted between 2011 and 2016 involving 105 men (40-74 years old), with average morning T < 300 ng/dl, given intramuscular T cypionate 200 mg every 2 weeks for 18 months. Subjects were divided into those with baseline T levels of <264 ng/dl (N = 43) and those with ≥264 ng/dl (N = 57). T and estradiol (E2) were measured by liquid chromatography/mass spectrometry; serum bone turnover markers (C-telopeptide [CTX], osteocalcin, and sclerostin), adiponectin, and leptin were measured by enzyme-linked immunosorbent assay; glycated hemoglobin (HbA1c) was measured by high-performance liquid chromatography; and areal BMD and body composition was measured by dual-energy x-ray absorptiometry (DXA).

RESULTS

Men with T < 264 ng/dl showed greater increases in total fat-free mass (FFM) at 18 months compared to those with T ≥ 264 ng/dl (4.2 ± 4.1 vs. 2.7 ± 3.8%; p = 0.047) and unadjusted appendicular FFM at 6 and 18 months (8.7 ± 11.5 vs. 4.4 ± 4.3%, 7.3 ± 11.6 vs. 2.4 ± 6.8%; p = 0.033 and p = 0.043, respectively). Men with T ≥ 264 ng/dl showed significant decreases in HbA1c at 12 months (-3.1 ± 9.2 vs. 3.2 ± 13.9%; p = 0.005), fasting glucose at 18 months (-4.2 ± 31.9 vs. 13.0 ± 57.3%; p = 0.040), LDL at 6 months (-6.4 ± 27.5 vs. 12.8 ± 44.1%; p = 0.034), and leptin at 18 months (-40.2 ± 35.1 vs. -27.6 ± 31.0%; p = 0.034) compared to those with T < 264 ng/dl. No significant differences in BMD and bone turnover markers were observed.

CONCLUSION

T therapy results in improvement in body composition irrespective of baseline T levels but T < 264 ng/dl is associated with greater improvement in FFM, whereas a T level of ≥264 ng/dl favors improvement in metabolic profile.

Effects of Testosterone Replacement Therapy on Glycolipid Metabolism Among Hypogonadal Men withT2DM: A Meta-Analysis And System Review Of Randomized Controlled Trials

Introduction

Testosterone can improve glucose metabolism through multiple cellular mechanisms. However, it remains unclear as to whether hypogonadal men with type 2 diabetes mellitus (T2DM) can benefit from testosterone replacement therapy (TRT).

Aims

To assess the relative effect of TRT on glycolipid metabolism among hypogonadal men with T2DM.

Methods

: Electronic literature searches of the Cochrane Library, PubMed, MEDLINE, and EMBASE databases were conducted, up to the end of October 2020. Only studies that used randomized controlled trials (RCTs) were included in our systematic review. Main outcome measures From these studies, we extracted certain outcomes including changes in insulin resistance, glucose metabolism, and lipid parameters.

Results

There were a total of 8 studies that met our criteria. Four of these studies either did not have a consistent treatment strategy, or the control groups used untreated patients rather than patients that had been given a placebo. Thus, results from these four studies contributed to the variability in treatment outcomes. In four of the examined RCTs, there was no change in either the dose or the type of antidiabetic medication prescribed. Based on the homeostatic model assessment of insulin resistance, the pooled WMD was −0.34, 95% confidence interval (CI; −1.02, 0.34), P = .33; For fasting plasma glucose, the pooled WMD was −0.27, 95% CI (−1.02, 0.48), P = .48, the pooled WMD for HbA1c% was −0.00, 95% CI (−1.08, 1.08), P = 1.00.

Conclusions

Although certain RCTs showed that TRT improved insulin resistance and glycolipid metabolism when compared with the placebo or untreated control groups, these findings may partly be due to changes in antidiabetic therapy during the course of the study. In the current meta-analysis, analyses showed that TRT did not significantly improve insulin resistance or glycolipid metabolism. Future studies need to be rigorous in design and delivery, and comprehensive descriptions of all aspects of their methods should be included to further enable a more accurate appraisal and interpretation of the results.

Yu X, Wei Z, Liu Y, et al. Effects of Testosterone Replacement Therapy on Glycolipid Metabolism Among Hypogonadal Men with T2DM: A Meta-Analysis And System Review Of Randomized Controlled Trials. Sex Med 2021;9:100403.

Testosterone replacement therapy in men with type 2 diabetes mellitus and functional hypogonadism -an Integrated Diabetes and Endocrine Academy (IDEA) consensus guideline

BACKGROUND

Though testosterone replacement therapy in men with organic hypogonadism is established, its role in men with type 2 diabetes mellitus (T2DM) and functional hypogonadism is unclear.

METHODS

Thirteen experts addressed ten topic-specific questions after an in-depth review of literature, where all relevant issues were critically evaluated.

RESULTS

Ten recommendations concerning diagnosis and management of men with T2DM and functional hypogonadism have been put forward.

CONCLUSION

Routine measurement of serum testosterone in all, and inappropriate replacement of testosterone in asymptomatic T2DM men with functional hypogonadism and borderline low serum testosterone values, is not recommended.

Testosterone therapy for prevention and reversal of type 2 diabetes in men with low testosterone

Men with obesity and/or type 2 diabetes (T2D) have a high prevalence of testosterone deficiency (TD). Similarly, men with TD have an increased risk of developing obesity and/or T2D, and further body fat accumulation and deterioration of glycemic control create a vicious cycle. The landmark testosterone for diabetes mellitus trial, the largest randomized controlled trial of testosterone therapy (TTh) to date, confirms the beneficial effects of TTh on fat loss and gain in muscle mass, and that TTh for 2 years significantly reduces the risk of incident T2D, and may also reverse T2D. The testosterone for diabetes mellitus trial suggests that TTh reduces the risk of T2D and results in greater improvement in sexual function and wellbeing, beyond lifestyle intervention alone.

Serum testosterone in Nigerian men with type 2 diabetes mellitus and its relationship with insulin sensitivity and glycemic control

BACKGROUND

There is increasing evidence that testosterone deficiency has key associations with insulin sensitivity and glycemic control. Its presence may therefore contribute to and/or exacerbate clinical disease in men with type 2 diabetes mellitus (T2DM). This study sought to determine the frequency of low free testosterone and explore its relationship with, insulin sensitivity and glycemic control among Nigerian men with T2DM.

METHODS

One hundred and four men with type 2 DM and one hundred and one apparently healthy non-diabetic men matched for age, were recruited into the study Socio-demographic data, anthropometric measurements and blood samples were obtained for measurement of serum total testosterone (TT), sex hormone binding globulin (SHBG), fasting plasma insulin, fasting plasma glucose (FPG), glycated hemoglobin (HbA1c) and fasting lipid profile in all the subjects. Insulin sensitivity (%IS) and free testosterone (CFT) were then calculated.

RESULTS

The median CFT for men with T2DM was significantly lower than that of non-diabetic controls (0.17 nmol/L vs 0.58 nmol/L respectively; P < 0.001). 52.9% of men with T2DM had low CFT, as compared with 21.4% amongst the non-diabetic controls; P < 0.001. Among men with T2DM, those with lower CFT had significantly lower median % S and higher mean HbA1c than those with normal CFT (37.0% versus 63.0%; P = 0.021 and 7.79 (2.03) % versus 7.02 (1.94) %; P = 0.038 respectively]. HbA1c had significant negative correlations with both CFT (correlation coefficient: -0.239 (P < 0.05) and TT (correlation coefficient: 0.354; P < 0.01. There was no significant difference in serum lipids when T2DM men with low serum CFT were compared with T2DM men with normal serum CFT levels.

CONCLUSION

We conclude that low serum testosterone is common among men with T2DM and has a significant association with glycemic control (HbA1c) and insulin sensitivity.

Lipid Metabolism is the common pathologic mechanism between Type 2 Diabetes Mellitus and Parkinson's disease

Although increasing evidence has suggested crosstalk between Parkinson's disease (PD) and type 2 diabetes mellitus (T2DM), the common mechanisms between the two diseases remain unclear. The aim of our study was to characterize the interconnection between T2DM and PD by exploring their shared biological pathways and convergent molecules. The intersections among the differentially expressed genes (DEGs) in the T2DM dataset GSE95849 and PD dataset GSE6613 from the Gene Expression Omnibus (GEO) database were identified as the communal DEGs between the two diseases. Then, an enrichment analysis, protein-protein interaction (PPI) network analysis, correlation analysis, and transcription factor-target regulatory network analysis were performed for the communal DEGs. As a result, 113 communal DEGs were found between PD and T2DM. They were enriched in lipid metabolism, including protein modifications that regulate metabolism, lipid synthesis and decomposition, and the biological effects of lipid products. All these pathways and their biological processes play important roles in both diseases. Fifteen hub genes identified from the PPI network could be core molecules. Their function annotations also focused on lipid metabolism. According to the correlation analysis and the regulatory network analysis based on the 15 hub genes, Sp1 transcription factor (SP1) could be a key molecule since it affected other hub genes that participate in the common mechanisms between PD and T2DM. In conclusion, our analyses reveal that changes in lipid metabolism could be a key intersection between PD and T2DM, and that SP1 could be a key molecule regulating these processes. Our findings provide novel points for the association between PD and T2DM.

Testosterone deficiency in men with Type 2 diabetes: pathophysiology and treatment

Epidemiological studies consistently demonstrate that lowered serum testosterone is not only common in men with established Type 2 diabetes, but also predicts future diabetic risks and increased mortality. Preclinical studies report plausible mechanisms by which low testosterone could mediate dysglycaemia. Exogenous testosterone treatment consistently reduces fat mass, increases muscle mass and improves insulin resistance in some studies, but the majority of currently available randomized controlled trials (RCTs) do not report a consistent glycaemic benefit. In men with diabetes, testosterone treatment effects on androgen deficiency-like clinical features are inconsistent, and effects on sexual dysfunction may be attenuated compared with men without diabetes. The long-term risks of testosterone treatment in older men without medical disease of the hypothalamic-pituitary-testicular axis are not known. Current RCTs are not definitive, owing to their small size, short duration and enrolment of men with mostly relatively good baseline glycaemic control not specifically selected for the presence of androgen deficiency symptoms. Although large, well-designed clinical trials are needed, given the benefit-risk ratio of testosterone treatment is not well understood, routine serum testosterone testing or testosterone treatment of asymptomatic men with Type 2 diabetes is currently not recommended. Carefully selected, symptomatic men with low testosterone who are informed of the lack of high-level evidence regarding the long-term benefits and risks of this approach may be offered a trial of testosterone treatment in combination with lifestyle measures, weight loss and optimization of comorbidities.

Androgen Therapy in Male Patients Suffering from Type 2 Diabetes: A Review of Benefits and Risks

BACKGROUND

The current estimated numbers of patients with Type 2 Diabetes (T2D) is believed to be close to 10% of the whole populations of many geographical regions, causing serious concerns over the resulting elevated morbidity and mortality as well as the impact on health care systems around the world. In addition to negatively affecting the quality of life, diabetes is associated with cardiovascular and cerebrovascular complications, indicating that appropriate drug therapy should not only deal with metabolic dysfunction but also protect the vascular system, kidney function and skeletal muscle mass from the effects of the epigenetic changes induced by hyperglycaemia.

OBJECTIVE

To provide an insight into the management of hypogonadism associated with T2D, this review focuses on clinical observations related to androgen therapy in qualified diabetic patients, and discusses the lines of evidence for its benefits and risks. The potential interactions of testosterone with medicines used by patients with T2D will also be discussed.

CONCLUSION

From recent clinical findings, it became evident that a considerable percentage of patients suffering from T2D manifested low serum testosterone and experienced diminished sexual activity, as well as reduced skeletal muscle mass and lower bone density. Although there are some controversies, Testosterone Replacement Therapy (TRT) for this particular population of patients appears to be beneficial overall only if it is implemented carefully and monitored regularly.

Metabolic Effects of Testosterone Replacement Therapy in Patients with Type 2 Diabetes Mellitus or Metabolic Syndrome: A Meta-Analysis

BACKGROUND

Testosterone replacement therapy (TRT) is commonly used for the treatment of hypogonadism in men, which is often associated with type 2 diabetes mellitus (T2DM) and metabolic syndrome (Mets). Recent compiling evidence shows that TRT has beneficial metabolic effects on these patients.

OBJECTIVE

A meta-analysis has been conducted to evaluate the effects of TRT on cardiovascular metabolic factors.

METHODS

We conducted a systemic search on PubMed, Embase, Cochrane Library, Wanfang, and CNKI and selected randomized controlled trials (RCTs) to include. The efficacy of TRT on glycemia, insulin sensitivity, lipid profile, and body weight was meta-analyzed by Review Manager.

RESULTS

A total of 18 RCTs, containing 1415 patients (767 in TRT and 648 in control), were enrolled for the meta-analysis. The results showed that TRT could reduce HbA1c (MD = -0.67, 95% CI -1.35, -0.19, and P=0.006) and improve HOMA-IR (homeostatic model assessment of insulin resistance) (SMD = -1.94, 95% CI -2.65, -1.23, and P < 0.0001). TRT could also decrease low-density lipoprotein (SMD = -0.50, 95% CI -0.82, -0.90, and P=0.002) and triglycerides (MD = -0.64, 95% CI -0.91, -0.36, and P < 0.0001). In addition, TRT could reduce body weight by 3.91 kg (MD = -3.91, 95% CI -4.14, -3.69, and P < 0.00001) and waist circumference by 2.8 cm (MD -2.80, 95% CI -4.38, -1.21 and P=0.0005). Erectile dysfunction (measured by IIEF-5) did not improve, while aging-related symptoms (measured by AMS scores) significantly improved.

CONCLUSIONS

TRT improves glycemic control, insulin sensitivity, and lipid parameters in hypogonadism patients with T2DM and MetS, partially through reducing central obesity.

Testosterone and Cardiovascular Risk: Meta-Analysis of Interventional Studies

BACKGROUND

The relationship between testosterone (T) and cardiovascular (CV) risk in men is conflicting.

AIM

To verify whether T therapy (TTh) represents a possible risk factor for CV morbidity and mortality.

METHODS

We conducted a random effect meta-analysis considering all available data from pharmaco-epidemiological studies as well as randomized placebo-controlled trials (RCTs).

OUTCOMES

CV mortality and morbidity were investigated.

RESULTS

After screening, 15 pharmaco-epidemiological and 93 RCT studies were considered. The analysis of pharmaco-epidemiological studies documented that TTh reduces overall mortality and CV morbidity. Conversely, in RCTs, TTh had no clear effect, either beneficial or detrimental, on the incidence of CV events. However, a protective role of TTh on CV morbidity was observed when studies enrolling obese (body mass index >30 kg/m²) patients were scrutinized (Mantel-Haenszel odds ratio 0.51 [95% CI 0.27-0.96]; P = .04), although this association disappeared when only high-quality RCTs were considered (Mantel-Haenszel odds ratio 0.64 [95% CI 0.22-1.88]; P = .42). Finally, an increased risk of CV diseases was observed in RCTs when T preparations were prescribed at dosages above those normally recommended, or when frail men were considered.

CLINICAL IMPLICATIONS

Pharmaco-epidemiological studies showed that TTh might reduce CV risk, but this effect was not confirmed when RCTs were considered.

STRENGTHS & LIMITATIONS

Meta-analysis of pharmaco-epidemiological studies indicates that TTh reduces overall mortality and CV morbidity. In addition, even in RCTs, a protective role of TTh on CV morbidity was envisaged when studies enrolling obese (body mass index >30 kg/m²) patients were considered. Pharmaco-epidemiological studies should be considered with caution due to the lack of completeness of follow-up and of the management of missing data. In addition, properly powered placebo-controlled RCTs with a primary CV end point, in men with late-onset hypo-gonadism, are not yet available. Finally, the duration of all studies evaluated in the present meta-analysis is relatively short, reaching a maximum of 3 years.

CONCLUSIONS

Data from RCTs suggest that treatment with T is not effective in reducing CV risk, however, when TTh is correctly applied, it is not associated with an increase in CV risk and it may have a beneficial effect in some sub-populations. Corona G, Rastrelli G, Di Pasquale G, et al. Testosterone and Cardiovascular Risk: Meta-Analysis of Interventional Studies. J Sex Med 2018;15:820-838.

A placebo-controlled randomized study with testosterone in Klinefelter syndrome: beneficial effects on body composition

CONTEXT AND OBJECTIVE

Males with Klinefelter syndrome (KS) are typically hypogonadal with a high incidence of metabolic disease, increased body fat and mortality. Testosterone treatment of hypogonadal patients decrease fat mass, increase lean body mass and improve insulin sensitivity, but whether this extends to patients with KS is presently unknown.

RESEARCH DESIGN AND METHODS

In a randomized, double-blind, placebo-controlled, BMI-matched cross-over study, 13 males with KS (age: 34.8 years; BMI: 26.7 kg/m2) received testosterone (Andriol®) 160 mg per day (testosterone) or placebo treatment for 6 months. Thirteen age- and BMI-matched healthy controls were recruited. DEXA scan, abdominal computed tomography (CT) scan and a hyperinsulinemic-euglycemic clamp, muscle strength and maximal oxygen uptake measurement were performed.

RESULTS

Total lean body mass and body fat mass were comparable between testosterone-naïve KS and controls using DEXA, whereas visceral fat mass, total abdominal and intra-abdominal fat by CT was increased (P < 0.05). Testosterone decreased total body fat (P = 0.01) and abdominal fat by CT (P = 0.04). Glucose disposal was similar between testosterone-naïve KS and controls (P = 0.3) and unchanged during testosterone (P = 0.8). Free fatty acid suppression during the clamp was impaired in KS and maximal oxygen uptake was markedly lower in KS, but both were unaffected by treatment. Testosterone increased hemoglobin and IGF-I.

CONCLUSION

Testosterone treatment in adult males with KS for 6 months leads to favorable changes in body composition with reductions in fat mass, including abdominal fat mass, but does not change measures of glucose homeostasis.

Cross-sectional and longitudinal associations between serum testosterone concentrations and hypertension: Results from the Fangchenggang Area Male Health and Examination Survey in China

BACKGROUND

Low testosterone concentrations have been suggested as a risk factor for hypertension, but their contribution to the development of hypertension is not well studied. We carried out a cohort study based on the results of an earlier cross-sectional investigation. We established the association between testosterone concentrations and hypertension.

METHOD

Data on 2427 healthy male subjects, aged from 17 to 88 y, were collected for the cross-sectional study. A representative sample of 853 individuals who did not suffer from hypertension at baseline was followed up for 4 y. Differences between the tertiles groups of sex hormones were analyzed, relative risks (RR) were estimated using binary logistic regression model.

RESULTS

In the cross-sectional analysis, the serum total testosterone (TT), free testosterone (FT), and bioavailable testosterone (BT) concentrations of the hypertensive population were lower than those of the non-hypertensive population. Binary logistic regression analysis showed that TT, BT, and FT were inversely associated with hypertension. Moreover, decreasing odds ratio (OR) was observed from the lowest tertile group to the highest tertile group. After multivariate adjustment, the correlation between FT, BT, and hypertension was attenuated. Statistically significant differences remained only in the middle tertile group of TT and in the highest tertile group of TT, FT, and BT. In the longitudinal analysis, the 4-y incidence of hypertension was higher in participants with lower TT than in those with higher TT. Subjects in the middle and highest tertile groups of TT had an RR of 0.35 (0.22-0.57) and 0.30 (0.18-0.50), respectively (P for trend <0.001). After further adjustments, these associations still remained statistically significant.

CONCLUSIONS

Serum TT, FT, and BT concentrations were inversely associated with blood pressure in man, and TT independent of age and body mass index (BMI) influences the development of hypertension. Furthermore, TT can be employed as a risk marker for hypertension in the identification of high-risk individuals.

GONADOPENIA AND AGING IN MEN

OBJECTIVE

The decrease in testosterone levels that occurs with aging has become an important clinical issue both due to the growth of the geriatric population and patient interest in testosterone therapy. The decision to assess for testosterone deficiency and the ability to determine whether the benefits exceed the risks require a comprehensive evaluation of the aging patient. This article is part of a series of papers focused on the endocrinology of aging. This review addresses common issues needed for clinical decision making, including how to interpret test results, differential diagnosis, potential impact of testosterone treatment on insulin resistance and cardiovascular disease, and options for therapy.

METHODS

Papers reviewed were identified through literature searches conducted on PubMed.

RESULTS

Assessment of testosterone levels in the geriatric male requires an understanding of the limitations of the assay that is used, the symptoms associated with low testosterone, the impact of comorbid conditions on levels, and risks of therapy. Successful treatment requires setting realistic expectations of the benefits of replacement therapy.

CONCLUSION

While the prevalence of low testosterone concentrations is increased with aging, the common comorbidities such as obesity and diabetes may contribute to changes in testosterone levels. Clinical trial evidence shows modest benefit for treatment of low testosterone in the presence of symptoms. Assessment of the geriatric male should include evaluation of their testosterone level in the context of their functional status and comorbidities.

ABBREVIATIONS

CDC = Centers for Disease Control and Prevention; CI = confidence interval; CVD = cardiovascular disease; DXA = dual-energy X-ray absorptiometry; EMAS = European Male Aging Study; FDA = U.S. Food and Drug Administration; FHS = Framingham Heart Study; HDL = high-density lipoprotein; HOMA-IR = homeostasis model assessment of insulin resistance; LH = luteinizing hormone; OR = odds ratio; PSA = prostate-specific antigen; SHBG = sex hormone-binding globulin; T2DM = type 2 diabetes mellitus; vBMD = volumetric bone mineral density.

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.

Effects of clomiphene citrate on male obesity-associated hypogonadism: a randomized, double-blind, placebo-controlled study

BACKGROUND

Obesity causes secondary hypogonadism (HG) in men. Standard testosterone (T) replacement therapy improves metabolic parameters but leads to infertility.

OBJECTIVE

To evaluate clomiphene citrate (CC) treatment of adult men with male obesity-associated secondary hypogonadism (MOSH).

DESIGN

Single-center, randomized, double-blind, placebo-controlled trial.

PARTICIPANTS

Seventy-eight men aged 36.5 ± 7.8 years with a body mass index (BMI) > 30 kg/m², total testosterone (TT) ≤ 300 ng/dL, and symptoms in the ADAM questionnaire.

INTERVENTION

Random allocation to receive 50 mg CC or placebo (PLB) for 12 weeks.

OUTCOMES

(1) Clinical features: ADAM and sexual behavior questionnaires; (2) hormonal profile: serum TT, free T, estradiol (E2), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and sex hormone-binding globulin (SHBG); (3) body composition: BMI, waist circumference, and bioelectric impedance analysis; (4) metabolic profile: blood pressure, fasting blood glucose, HbA1c, insulin, HOMA-IR, and lipid profile; (5) endothelial function: flow-mediated dilation of the brachial artery, quantitative assessment of endothelial progenitor cells and serum sICAM-1, sVCAM-1, and selectin-sE levels; (6) safety aspects: hematocrit, serum prostate-specific antigen, International Prostate Symptom Score, and self-reported adverse effects.

RESULTS

There was an improvement in one sexual complaint (weaker erections; P < 0.001); increases (P < 0.001) in TT, free T, E2, LH, FSH, and SHBG; and improvements in lean mass (P < 0.001), fat-free mass (P = 0.004), and muscle mass (P < 0.001) in the CC group. CC reduced HDL (P < 0.001). No statistically significant differences were seen in endothelial function.

CONCLUSIONS

CC appeared to effectively improve the hormonal profile and body composition. CC may be an alternative treatment for MOSH in adult men.

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.

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.

Effect of testosterone on insulin sensitivity, oxidative metabolism and body composition in aging men with type 2 diabetes on metformin monotherapy

AIMS

To evaluate the effect of testosterone replacement therapy (TRT) on body composition, insulin sensitivity, oxidative metabolism and glycaemic control in aging men with lowered bioavailable testosterone (BioT) levels and type 2 diabetes mellitus (T2D) controlled on metformin monotherapy.

MATERIALS AND METHODS

We conducted a randomized, double-blind, placebo-controlled study in 39 men aged 50-70 years with BioT levels <7.3 nmol/L and T2D treated with metformin monotherapy. Patients were randomized to testosterone gel (TRT, n = 20) or placebo (n = 19) for 24 weeks. Lean body mass (LBM), total and regional fat mass were measured using whole-body dual-energy X-ray absorptiometry scans. Whole-body peripheral insulin sensitivity, endogenous glucose production (EGP) and substrate oxidation were assessed by euglycaemic-hyperinsulinaemic clamp with glucose tracer and combined with indirect calorimetry. Coefficients (β) represent the placebo-controlled mean effect of intervention.

RESULTS

LBM (β = 1.9 kg, p = 0.001) increased after TRT, while total fat mass (β = -1.3 kg, p = 0.009), fat mass trunk (β = -0.7 kg, p = 0.043), fat mass legs (β = -0.7 kg, p = 0.025), fat mass arms (β = -0.3 kg, p = 0.001), and HDL cholesterol (β = -0.11 mmol/L, p = 0.009) decreased after TRT compared with placebo. Insulin-stimulated glucose disposal rates did not change in response to TRT compared with placebo (p = 0.18). Moreover, glycated haemoglobin, and basal and insulin-stimulated rates of EGP, lipid- and glucose-oxidation were unaltered after TRT.

CONCLUSION

TRT in aging men with lowered BioT levels and T2D controlled on metformin monotherapy improved body composition; however, glycaemic control, peripheral insulin sensitivity, EGP and substrate metabolism were unchanged.

Adult-Onset Hypogonadism

In August 2015, an expert colloquium commissioned by the Sexual Medicine Society of North America (SMSNA) convened in Washington, DC, to discuss the common clinical scenario of men who present with low testosterone (T) and associated signs and symptoms accompanied by low or normal gonadotropin levels. This syndrome is not classical primary (testicular failure) or secondary (pituitary or hypothalamic failure) hypogonadism because it may have elements of both presentations. The panel designated this syndrome adult-onset hypogonadism (AOH) because it occurs commonly in middle-age and older men. The SMSNA is a not-for-profit society established in 1994 to promote, encourage, and support the highest standards of practice, research, education, and ethics in the study of human sexual function and dysfunction. The panel consisted of 17 experts in men's health, sexual medicine, urology, endocrinology, and methodology. Participants declared potential conflicts of interest and were SMSNA members and nonmembers. The panel deliberated regarding a diagnostic process to document signs and symptoms of AOH, the rationale for T therapy, and a monitoring protocol for T-treated patients. The evaluation and management of hypogonadal syndromes have been addressed in recent publications (ie, the Endocrine Society, the American Urological Association, and the International Society for Sexual Medicine). The primary purpose of this document was to support health care professionals in the development of a deeper understanding of AOH, particularly in how it differs from classical primary and secondary hypogonadism, and to provide a conceptual framework to guide its diagnosis, treatment, and follow-up.

Predictive value of serum testosterone for type 2 diabetes risk assessment in men

BACKGROUND

Effective prevention of type 2 diabetes (T2D) requires early identification of high-risk individuals who might benefit from intervention. We sought to determine whether low serum testosterone, a novel risk factor for T2D in men, adds clinically meaningful information beyond current T2D risk models.

METHODS

The Men Androgen Inflammation Lifestyle Environment and Stress (MAILES) study population consists of 2563 community-dwelling men aged 35-80 years in Adelaide, Australia. Of the MAILES participants, 2038 (80.0 %) provided information at baseline (2002-2006) and follow-up (2007-2010). After excluding participants with diabetes (n = 317), underweight (n = 5), and unknown BMI status (n = 11) at baseline; and unknown diabetes status (n = 50) at follow-up; 1655 participants were followed for 5 years. T2D at baseline and follow-up was defined by self-reported diabetes, or fasting plasma glucose (FPG) ≥7.0 mmol/L (126.1 mg/dL), or glycated haemoglobin (HbA1c) ≥6.5 %, or diabetes medications. Risk models were tested using logistic regression models. Sensitivity, specificity, positive predictive values (PPV) were used to identify the optimal cut-off point for low serum testosterone for incident T2D and the area under the receiver operating characteristic (AROC) curve was used to summarise the predictive power of the model. 15.5 % of men had at least one missing predictor variable; addressed through multiple imputation.

RESULTS

The incidence rate of T2D was 8.9 % (147/1655) over a median follow-up of 4.95 years (interquartile range: 4.35-5.00). Serum testosterone level predicted incident T2D (relative risk 0.96 [95 % CI: 0.92,1.00], P = 0.032) independent of current risk models including the AUSDRISK, but did not improve corresponding AROC statistics. A cut-off point of <16 nmol/L for low serum testosterone, which classified about 43 % of men, returned equal sensitivity (61.3 % [95 % CI: 52.6,69.4]) and specificity (58.3 % [95 % CI: 55.6,60.9) for predicting T2D risk, with a PPV of 12.9 % (95 % CI: 10.4,15.8).

CONCLUSIONS

Low serum testosterone predicts an increased risk of developing T2D in men over 5 years independent of current T2D risk models applicable for use in routine clinical practice. Screening for low serum testosterone in addition to risk factors from current T2D risk assessment models or tools, including the AUSDRISK, would identify a large subgroup of distinct men who might benefit from targeted preventive interventions.

THERAPY OF ENDOCRINE DISEASE: Testosterone supplementation and body composition: results from a meta-analysis study

OBJECTIVE

The role of testosterone (T) in regulating body composition is conflicting. Thus, our goal is to meta-analyse the effects of T supplementation (TS) on body composition and metabolic outcomes.

METHODS

All randomized controlled trials (RCTs) comparing the effect of TS on different endpoints were considered.

RESULTS

Overall, 59 trials were included in the study enrolling 3029 and 2049 patients in TS and control groups respectively. TS was associated with any significant modification in body weight, waist circumference and BMI. Conversely, TS was associated with a significant reduction in fat and with an increase in lean mass as well as with a reduction of fasting glycaemia and insulin resistance. The effect on fasting glycaemia was even higher in younger individuals and in those with metabolic diseases. When only RCTs enrolling hypogonadal (total T <12  mol/l) subjects were considered, a reduction of total cholesterol as well as triglyceride (TGs) levels were also detected. Conversely, an improvement in HDL cholesterol levels as well as in both systolic and diastolic blood pressure was not observed.

CONCLUSION

Our data suggest that TS is able to improve body composition and glycometabolic profile particularly in younger subjects and in those with metabolic disturbances. Specifically designed studies are urgently needed to confirm this point.

Prevalence, Pathophysiology, and Management of Androgen Deficiency in Men with Metabolic Syndrome, Type 2 Diabetes Mellitus, or Both

The prevalence of type 2 diabetes mellitus (T2DM) and metabolic syndrome (MetS) has increased in the United States over the past 40 years. These conditions, long linked with many cardiovascular complications, have recently been linked with androgen or testosterone deficiency in men. Several pathophysiologic hypotheses exist regarding this association, with the most widely reported a relationship to obesity and insulin resistance. Several randomized trials have confirmed that when testosterone replacement therapy is given to patients with T2DM, MetS, or both, metabolic parameters such as waist circumference, hemoglobin A1c , and systolic blood pressure are significantly reduced by up to 11 cm, 1.9%, and 23 mm Hg, respectively. This has not, however, resulted in improved cardiovascular outcomes, as evidenced in studies that found increased rates of cardiovascular events following testosterone replacement therapy. In this review, we summarize the relevant literature regarding the pathophysiology and management of androgen deficiency in men with T2DM, MetS, or both.

Insulin Resistance and Inflammation in Hypogonadotropic Hypogonadism and Their Reduction After Testosterone Replacement in Men With Type 2 Diabetes

OBJECTIVE

One-third of men with type 2 diabetes have hypogonadotropic hypogonadism (HH). We conducted a randomized placebo-controlled trial to evaluate the effect of testosterone replacement on insulin resistance in men with type 2 diabetes and HH.

RESEARCH DESIGN AND METHODS

A total of 94 men with type 2 diabetes were recruited into the study; 50 men were eugonadal, while 44 men had HH. Insulin sensitivity was calculated from the glucose infusion rate (GIR) during hyperinsulinemic-euglycemic clamp. Lean body mass and fat mass were measured by DEXA and MRI. Subcutaneous fat samples were taken to assess insulin signaling genes. Men with HH were randomized to receive intramuscular testosterone (250 mg) or placebo (1 mL saline) every 2 weeks for 24 weeks.

RESULTS

Men with HH had higher subcutaneous and visceral fat mass than eugonadal men. GIR was 36% lower in men with HH. GIR increased by 32% after 24 weeks of testosterone therapy but did not change after placebo (P = 0.03 for comparison). There was a decrease in subcutaneous fat mass (-3.3 kg) and increase in lean mass (3.4 kg) after testosterone treatment (P < 0.01) compared with placebo. Visceral and hepatic fat did not change. The expression of insulin signaling genes (IR-β, IRS-1, AKT-2, and GLUT4) in adipose tissue was significantly lower in men with HH and was upregulated after testosterone treatment. Testosterone treatment also caused a significant fall in circulating concentrations of free fatty acids, C-reactive protein, interleukin-1β, tumor necrosis factor-α, and leptin (P < 0.05 for all).

CONCLUSIONS

Testosterone treatment in men with type 2 diabetes and HH increases insulin sensitivity, increases lean mass, and decreases subcutaneous fat.

Effects of testosterone treatment on glucose metabolism and symptoms in men with type 2 diabetes and the metabolic syndrome: a systematic review and meta-analysis of randomized controlled clinical trials

CONTEXT

The effects of testosterone treatment on glucose metabolism and other outcomes in men with type 2 diabetes (T2D) and/or the metabolic syndrome are controversial.

OBJECTIVE

To perform a systematic review and meta-analysis of placebo-controlled double-blind randomized controlled clinical trials (RCT) of testosterone treatment in men with T2D and/or the metabolic syndrome.

DATA SOURCES

A systematic search of RCTs was conducted using Medline, Embase and the Cochrane Register of controlled trials from inception to July 2014 followed by a manual review of the literature.

STUDY SELECTION

Eligible studies were published placebo-controlled double-blind RCTs published in English.

DATA EXTRACTION

Two reviewers independently selected studies, determined study quality and extracted outcome and descriptive data.

DATA SYNTHESIS

Of the 112 identified studies, seven RCTs including 833 men were eligible for the meta-analysis. In studies using a simple linear equation to calculate the homeostatic model assessment of insulin resistance (HOMA1), testosterone treatment modestly improved insulin resistance, compared to placebo, pooled mean difference (MD) -1·58 [-2·25, -0·91], P < 0·001. The treatment effect was nonsignificant for RCTs using a more stringent computer-based equation (HOMA2), MD -0·19 [-0·86, 0·49], P = 0·58). Testosterone treatment did not improve glycaemic (HbA1c) control, MD -0·15 [-0·39, 0·10], P = 0·25, or constitutional symptoms, Aging Male Symptom score, MD -2·49 [-5·81, 0·83], P = 0·14).

CONCLUSIONS

This meta-analysis does not support the routine use of testosterone treatment in men with T2D and/or the metabolic syndrome without classical hypogonadism. Additional studies are needed to determine whether hormonal interventions are warranted in selected men with T2D and/or the metabolic syndrome.

Critical Update of the 2010 Endocrine Society Clinical Practice Guidelines for Male Hypogonadism: A Systematic Analysis

"Testosterone Therapy in Men With Androgen Deficiency Syndromes: An Endocrine Society Clinical Practice Guideline" (Guidelines), published in 2010, serves as an important guide for the treatment of hypogonadal men. Using the Guidelines as a basis, we searched for the most recent level 1 evidence that continues to support the recommendations or provide an impetus to modify all or some of them. We performed a systematic analysis with a PubMed query from January 1, 2010, through March 2, 2015, using the following key words: testosterone/deficiency, testosterone/therapeutic use, cardiovascular, morbidity, mortality, screening, sexual function, lower urinary tract symptoms, obstructive sleep apnea, prostate cancer, fertility, bone mineral density, osteoporosis, quality of life, cognitive, erectile dysfunction, and adverse effects. We identified 17 trials representing level 1 evidence that specifically addressed recommendations made in the Guidelines. Trials examining outcomes of testosterone replacement therapy in men with severe lower urinary tract symptoms and untreated obstructive sleep apnea were identified, potentially refuting the current dogma against treatment in the setting of these conditions. Hypogonadal men with type 2 diabetes mellitus and metabolic syndrome were examined in several trials, demonstrating the beneficial effects of therapy on sexual function and insulin sensitivity. Several trials served as reinforcing evidence for the beneficial effects of testosterone therapy on osteoporosis, muscle strength, and symptoms of frailty. As in the Guidelines, inconsistent effects on quality of life, well-being, and erectile function were also noted in publications. Despite controversies surrounding cardiovascular morbidity and treatment in the setting of prostate cancer, no studies examining these issues as primary end points were identified. The low number of eligible studies since 2010 is a limitation of this analysis.

Transcriptomic analysis of hepatic responses to testosterone deficiency in miniature pigs fed a high-cholesterol diet

Background

Recent studies have indicated that low serum testosterone levels are associated with increased risk of developing hepatic steatosis; however, the mechanisms mediating this phenomenon have not been fully elucidated. To gain insight into the role of testosterone in modulating hepatic steatosis, we investigated the effects of testosterone on the development of hepatic steatosis in pigs fed a high-fat and high-cholesterol (HFC) diet and profiled hepatic gene expression by RNA-Seq in HFC-fed intact male pigs (IM), castrated male pigs (CM), and castrated male pigs with testosterone replacement (CMT).

Results

Serum testosterone levels were significantly decreased in CM pigs, and testosterone replacement attenuated castration-induced testosterone deficiency. CM pigs showed increased liver injury accompanied by increased hepatocellular steatosis, inflammation, and elevated serum alanine aminotransferase levels compared with IM pigs. Moreover, serum levels of total cholesterol, low-density lipoprotein cholesterol, and triglycerides were markedly increased in CM pigs. Testosterone replacement decreased serum and hepatic lipid levels and improved liver injury in CM pigs. Compared to IM and CMT pigs, CM pigs had lower serum levels of superoxide dismutase but higher levels of malondialdehyde. Gene expression analysis revealed that upregulated genes in the livers of CM pigs were mainly enriched for genes mediating immune and inflammatory responses, oxidative stress, and apoptosis. Surprisingly, the downregulated genes mainly included those that regulate metabolism-related processes, including fatty acid oxidation, steroid biosynthesis, cholesterol and bile acid metabolism, and glucose metabolism. KEGG analysis showed that metabolic pathways, fatty acid degradation, pyruvate metabolism, the tricarboxylic acid cycle, and the nuclear factor-kappaB signaling pathway were the major pathways altered in CM pigs.

Conclusions

This study demonstrated that testosterone deficiency aggravated hypercholesterolemia and hepatic steatosis in pigs fed an HFC diet and that these effects could be reversed by testosterone replacement therapy. Impaired metabolic processes, enhanced immune and inflammatory responses, oxidative stress, and apoptosis may contribute to the increased hepatic steatosis induced by testosterone deficiency and an HFC diet. These results deepened our understanding of the molecular mechanisms of testosterone deficiency-induced hepatic steatosis and provided a foundation for future investigations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1283-0) contains supplementary material, which is available to authorized users.

The effect of testosterone replacement therapy on prostate-specific antigen (PSA) levels in men being treated for hypogonadism: a systematic review and meta-analysis

Testosterone replacement therapy is used for the treatment of age-related male hypogonadism, and prostate-specific antigen (PSA) is a primary screening tool for prostate cancer. The systematic review and meta-analysis aimed to determine the effect of testosterone replacement therapy on PSA levels.Medline, Cochrane Library, EMBASE, and Google Scholar databases were searched until February 28, 2014, and inclusion criteria were as follows: randomized controlled trial; intervention group received testosterone/androgen replacement therapy; control group did not receive treatment; and no history of prostate cancer. The primary outcome was change of PSA level between before and after treatment. Secondary outcomes were elevated PSA level after treatment, and the number of patients who developed prostate cancer.After initially identifying 511 articles, 15 studies with a total of 739 patients that received testosterone replacement and 385 controls were included. The duration of treatment ranged from 3 to 12 months. Patients treated with testosterone tended to have higher PSA levels, and thus a greater change than those that received control treatments (difference in means of PSA levels = 0.154, 95% confidence interval [CI] 0.069 to 0.238, P < 0.001). The difference in means of PSA levels were significant higher for patients that received testosterone intramuscularly (IM) than controls (difference in means of PSA levels = 0.271, 95% CI 0.117-0.425, P = 0.001). Elevated PSA levels after treatment were similar between patients that received treatment and controls (odds ratio [OR] = 1.02, 95% CI 0.48-2.20, P = 0.953). Only 3 studies provided data with respect to the development of prostate cancer, and rates were similar between those that received treatment and controls.Testosterone replacement therapy does not increase PSA levels in men being treated for hypogonadism, except when it is given IM and even the increase with IM administration is minimal.

Human androgen deficiency: insights gained from androgen receptor knockout mouse models

The mechanism of androgen action is complex. Recently, significant advances have been made into our understanding of how androgens act via the androgen receptor (AR) through the use of genetically modified mouse models. A number of global and tissue-specific AR knockout (ARKO) models have been generated using the Cre-loxP system which allows tissue- and/or cell-specific deletion. These ARKO models have examined a number of sites of androgen action including the cardiovascular system, the immune and hemopoetic system, bone, muscle, adipose tissue, the prostate and the brain. This review focuses on the insights that have been gained into human androgen deficiency through the use of ARKO mouse models at each of these sites of action, and highlights the strengths and limitations of these Cre-loxP mouse models that should be considered to ensure accurate interpretation of the phenotype.

Metabolic effects of testosterone replacement therapy on hypogonadal men with type 2 diabetes mellitus: a systematic review and meta-analysis of randomized controlled trials

This systematic review was aimed at assessing the metabolic effects of testosterone replacement therapy (TRT) on hypogonadal men with type 2 diabetes mellitus (T2DM). A literature search was performed using the Cochrane Library, EMBASE and PubMed. Only randomized controlled trials (RCTs) were included in the meta-analysis. Two reviewers retrieved articles and evaluated the study quality using an appropriate scoring method. Outcomes including glucose metabolism, lipid parameters, body fat and blood pressure were pooled using a random effects model and tested for heterogeneity. We used the Cochrane Collaboration's Review Manager 5.2 software for statistical analysis. Five RCTs including 351 participants with a mean follow-up time of 6.5-months were identified that strictly met our eligibility criteria. A meta-analysis of the extractable data showed that testosterone reduced fasting plasma glucose levels (mean difference (MD): −1.10; 95% confidence interval (CI) (−1.88, −0.31)), fasting serum insulin levels (MD: −2.73; 95% CI (−3.62, −1.84)), HbA1c % (MD: −0.87; 95% CI (−1.32, −0.42)) and triglyceride levels (MD: −0.35; 95% CI (−0.62, −0.07)). The testosterone and control groups demonstrated no significant difference for other outcomes. In conclusion, we found that TRT can improve glycemic control and decrease triglyceride levels of hypogonadal men with T2DM. Considering the limited number of participants and the confounding factors in our systematic review; additional large, well-designed RCTs are needed to address the metabolic effects of TRT and its long-term influence on hypogonadal men with T2DM.

Cardiovascular risk associated with testosterone-boosting medications: a systematic review and meta-analysis

INTRODUCTION

Recent reports have significantly halted the enthusiasm regarding androgen-boosting; suggesting that testosterone supplementation (TS) increases cardiovascular (CV) events.

AREAS COVERED

In order to overcome some of the limitations of the current evidence, the authors performed an updated systematic review and meta-analysis of all placebo-controlled randomized clinical trials (RCTs) on the effect of TS on CV-related problems. Out of 2747 retrieved articles, 75 were analyzed, including 3016 and 2448 patients in TS and placebo groups, respectively, and a mean duration of 34 weeks. Our analyses, performed on the largest number of studies collected so far, indicate that TS is not related to any increase in CV risk, even when composite or single adverse events were considered. In RCTs performed in subjects with metabolic derangements a protective effect of TS on CV risk was observed.

EXPERT OPINION

The present systematic review and meta-analysis does not support a causal role between TS and adverse CV events. Our results are in agreement with a large body of literature from the last 20 years supporting TS of hypogonadal men as a valuable strategy in improving a patient's metabolic profile, reducing body fat and increasing lean muscle mass, which would ultimately reduce the risk of heart disease.

Effect of testosterone treatment on glucose metabolism in men with type 2 diabetes: a randomized controlled trial

OBJECTIVE

To determine whether testosterone therapy improves glucose metabolism in men with type 2 diabetes (T2D) and lowered testosterone.

RESEARCH DESIGN AND METHODS

We conducted a randomized, double-blind, parallel, placebo-controlled trial in 88 men with T2D, aged 35-70 years with an HbA1c ≤8.5% (69 mmol/mol), and a total testosterone level, measured by immunoassay, of ≤12.0 nmol/L (346 ng/dL). Participants were randomly assigned to 40 weeks of intramuscular testosterone undecanoate (n = 45) or matching placebo (n = 43). All study subjects were included in the primary analysis. Seven men assigned to testosterone and six men receiving placebo did not complete the study. Main outcome measures were insulin resistance by homeostatic model assessment (HOMA-IR, primary outcome) and glycemic control by HbA1c (secondary outcome).

RESULTS

Testosterone therapy did not improve insulin resistance (mean adjusted difference [MAD] for HOMA-IR compared with placebo -0.08 [95% CI -0.31 to 0.47; P = 0.23]) or glycemic control (MAD HbA1c 0.36% [0.0-0.7]; P = 0.05), despite a decrease in fat mass (MAD -2.38 kg [-3.10 to -1.66]; P < 0.001) and an increase in lean mass (MAD 2.08 kg [1.52-2.64]; P < 0.001). Testosterone therapy reduced subcutaneous (MAD -320 cm(3) [-477 to -163]; P < 0.001) but not visceral abdominal adipose tissue (MAD 140 cm(3) [-89 to 369]; P = 0.90).

CONCLUSIONS

Testosterone therapy does not improve glucose metabolism or visceral adiposity in obese men with moderately controlled T2D and modest reductions in circulating testosterone levels typical for men with T2D.

The treatment of late-onset hypogonadism

Late-onset hypogonadism (LOH) in aging men is a clinical and biochemical syndrome caused by an age-related decline in testosterone. Despite published in guidelines and recommendations, uncertainty surrounds the profile of clinical symptoms as well as the biochemical threshold of diagnosis. The only evidence-based treatment of late-onset hypogonadism is testosterone replacement therapy. The actual available evidence of the long-term risks and outcomes of testosterone-replacement therapy remains very limited, and carefully designed placebo-controlled trials of testosterone administration to assess the risks and benefits of such a therapy are required. Until such evidence is available, testosterone treatment should be restricted to elderly men with very low testosterone levels in the presence of clinical symptoms, and the advantages and disadvantages need to be accurately assessed. Careful monitoring of potential side effects is necessary. The purpose of this review is to discuss what is known and what remains unclear with respect to the benefits and risks of testosterone replacement treatment.

Testosterone and glucose metabolism in men: current concepts and controversies

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

The role of hypogonadism in Klinefelter syndrome

Klinefelter syndrome (KS) (47, XXY) is the most abundant sex-chromosome disorder, and is a common cause of infertility and hypogonadism in men. Most men with KS go through life without knowing the diagnosis, as only 25% are diagnosed and only a few of these before puberty. Apart from hypogonadism and azoospermia, most men with KS suffer from some degree of learning disability and may have various kinds of psychiatric problems. The effects of long-term hypogonadism may be diffi cult to discern from the gene dose effect of the extra X-chromosome. Whatever the cause, alterations in body composition, with more fat and less muscle mass and diminished bone mineral mass, as well as increased risk of metabolic consequences, such as type 2 diabetes and the metabolic syndrome are all common in KS. These findings should be a concern as they are not simply laboratory findings; epidemiological studies in KS populations show an increased risk of both hospitalization and death from various diseases. Testosterone treatment should be offered to KS patients from early puberty, to secure a proper masculine development, nonetheless the evidence is weak or nonexisting, since no randomized controlled trials have ever been published. Here, we will review the current knowledge of hypogonadism in KS and the rationale for testosterone treatment and try to give our best recommendations for surveillance of this rather common, but often ignored, syndrome.