The effect of testosterone replacement therapy on adipocytokines and C-reactive protein in hypogonadal men with type 2 diabetes

Localization of adiponectin and its receptor and its possible roles in the ovary of a vespertilionid bat, Scotophilus heathi

The aim of this study was to evaluate the seasonal variation in serum adiponectin levels and ovarian expression of adiponectin and its receptor in the Scotophilus heathi bat and their relationship to the changes in the body fat mass, serum insulin and luteinizing hormone (LH) levels, and ovarian activity. A very high level of circulating adiponectin was found during recrudescence, whereas a very low level of circulating adiponectin was observed during pre-ovulatory period. The increased circulating adiponectin level coincided with fat deposition, insulin resistance and hyperinsulinemia (HI) in S. heathi. Immunocytochemical study in the ovary of bat showed localization of adiponectin mainly in thecal-interstitial cells (TICs), and adiponectin receptor 1 (AdipoR1) in the granulosa cells of growing follicles, but showed no staining in atretic follicle. Seasonal changes in ovarian adiponectin and AdipoR1 levels showed two peaks (during recrudescence and ovulatory phases) coinciding with two periods of follicular development. Adiponectin in the absence of LH, as occur during recrudescence, stimulates androstenedione (A4) synthesis in vitro by up-regulating the insulin receptor (IR). Adiponectin in presence of LH, as occur during pre-ovulatory phase, inhibits A4 synthesis in vitro by down-regulating androgen receptor (AR). Further, the in vitro study showed that adiponectin, in presence of LH, also promotes luteinizing hormone receptor (LH-R) and steroidogenic acute regulatory protein (StAR) level in the ovary, which might help in development of ovulatory follicles. In brief, adiponectin in the absence of LH induces increased A4 synthesis and consequently the condition of delayed ovulation, whereas in the presence LH suppresses both synthesis and action of A4 and thus induces preovulatory condition in the ovary of S. heathi.

Testosterone as potential effective therapy in treatment of obesity in men with testosterone deficiency: a review

OBJECTIVE

Obesity negatively affects human health. Limiting food intake, while producing some weight loss, results in reduction of lean body mass. Combined with moderate exercise it produces significant weight loss, maintains lean body mass and improves insulin sensitivity, but appears difficult to adhere to. Bariatric surgery is clinically effective for severely obese individuals compared with non-surgical interventions, but has limitations. Clinical and pre-clinical studies have implicated a role for testosterone (T) in the patho-physiology of obesity.

EVIDENCE ACQUISITION AND SYNTHESIS

A literature search in PubMed on the role of T in counteracting obesity and its complications.

RESULTS

Obesity per se impairs testicular T biosynthesis. Furthermore, lower-than-normal T levels increase accumulation of fat depots, particularly abdominal (visceral) fat. This fat distribution is associated with development of metabolic syndrome (MetS) and its sequels, namely type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). T treatment reverses fat accumulation with significant improvement in lean body mass, insulin sensitivity and biochemical profiles of cardiovascular risk. The contribution of T to combating obesity in hypogonadal men remains largely unknown to medical professionals managing patients with obesity and metabolic syndrome. Many physicians associate T treatment in men with risks for prostate malignancy and CVD. These beliefs are not supported by recent insights.

CONCLUSION

While overall treatment of obesity is unsuccessful, T treatment of hypogonadal men may be effective, also because it improves mood, energy, reduces fatigue and may motivate men to adhere to diet and exercise regimens designed to combat obesity.

Testosterone therapy decreases subcutaneous fat and adiponectin in aging men

OBJECTIVE

Testosterone therapy increases lean body mass and decreases total fat mass in aging men with low normal testosterone levels. The major challenge is, however, to determine whether the metabolic consequences of testosterone therapy are overall positive. We have previously reported that 6-month testosterone therapy did not improve insulin sensitivity. We investigated the effect of testosterone therapy on regional body fat distribution and on the levels of the insulin-sensitizing adipokine, adiponectin, in aging men with low normal bioavailable testosterone levels.

DESIGN

A randomized, double-blinded, placebo-controlled study on 6-month testosterone treatment (gel) in 38 men, aged 60-78 years, with bioavailable testosterone <7.3 nmol/l, and a waist circumference >94 cm.

METHODS

Central fat mass (CFM) and lower extremity fat mass (LEFM) were measured by dual X-ray absorptiometry. Subcutaneous abdominal adipose tissue (SAT), visceral adipose tissue (VAT), and thigh subcutaneous fat area (TFA) were measured by magnetic resonance imaging. Adiponectin levels were measured using an in-house immunofluorometric assay. Coefficients (b) represent the placebo-controlled mean effect of intervention.

RESULTS

LEFM was decreased (b = -0.47 kg, P = 0.07) while CFM did not change significantly (b = -0.66 kg, P = 0.10) during testosterone therapy. SAT (b = -3.0%, P = 0.018) and TFA (b = -3.0%, P < 0.001) decreased, while VAT (b = 1.0%, P = 0.54) remained unchanged. Adiponectin levels decreased during testosterone therapy (b = -1.3 mg/l, P = 0.001).

CONCLUSION

Testosterone therapy decreased subcutaneous fat on the abdomen and lower extremities, but visceral fat was unchanged. Moreover, adiponectin levels were significantly decreased during testosterone therapy.

Testosterone, SHBG and differential white blood cell count in middle-aged and older men

OBJECTIVE

Low-grade chronic inflammation is increasingly being implicated in cardiovascular disease (CVD) etiology and may represent an alternative pathway through which testosterone and sex hormone-binding globulin (SHBG) influence CVD risk. We examined the associations between endogenous testosterone, SHBG and total and differential white blood cell (WBC) counts in men.

METHODS

Cross-sectional study of 2418 men aged 40-78 years from the Norfolk population of European Prospective Investigation into Cancer (EPIC-Norfolk) who had no history of CVD or cancer and complete data on sex hormones (total testosterone (TT), SHBG and free testosterone (FT)) and WBC counts. Associations between sex hormones and WBC counts were assessed using linear regression models.

RESULTS

Higher SHBG and TT levels were associated with lower WBC counts. After adjustment for age, BMI, smoking, physical activity and diabetes status, total WBC count decreased by 0.163 (95% CI -0.236; -0.091) and 0.102 (-0.170; -0.034) per standard deviation (SD) increase in SHBG and TT respectively. Associations of SHBG and TT with total WBC count were mainly accounted for by a lower granulocyte count (β coefficient=-0.132 (-0.194; -0.070) per SD increase in SHBG and β coefficient=-0.104 (-0.161; -0.046) per SD increase in TT). No associations between FT and total and differential WBC counts were found.

CONCLUSIONS

Endogenous TT and SHBG levels are inversely associated with total WBC and granulocyte count in middle-aged and older men. Even though the underlying mechanism and causal directionality requires further exploration, these results support a link between hormonal status and low-grade inflammation.

Hypogonadism in the aging male diagnosis, potential benefits, and risks of testosterone replacement therapy

Hypogonadism in older men is a syndrome characterized by low serum testosterone levels and clinical symptoms often seen in hypogonadal men of younger age. These symptoms include decreased libido, erectile dysfunction, decreased vitality, decreased muscle mass, increased adiposity, depressed mood, osteopenia, and osteoporosis. Hypogonadism is a common disorder in aging men with a significant percentage of men over 60 years of age having serum testosterone levels below the lower limits of young male adults. There are a variety of testosterone formulations available for treatment of hypogonadism. Data from many small studies indicate that testosterone therapy offers several potential benefits to older hypogonadal men. A large multicenter NIH supported double blind, placebo controlled study is ongoing, and this study should greatly enhance the information available on efficacy and side effects of treatment. While safety data is available across many age groups, there are still unresolved concerns associated with testosterone therapy. We have reviewed the diagnostic methods as well as benefits and risks of testosterone replacement therapy for hypogonadism in aging men.

Connecting the Lines between Hypogonadism and Atherosclerosis

Epidemiological studies show that atherosclerotic cardiovascular disease is a leading cause of morbidity and mortality worldwide and point to gender differences with ageing males being at highest risk. Atherosclerosis is a complex process that has several risk factors and mediators. Hypogonadism is a commonly undiagnosed disease that has been associated with many of the events, and risk factors leading to atherosclerosis. The mechanistic relations between testosterone levels, atherosclerotic events, and risk factors are poorly understood in many instances, but the links are clear. In this paper, we summarize the research journey that explains the link between hypogonadism, each of the atherosclerotic events, and risk factors. We look into the different areas from which lessons could be learned, including epidemiological studies, animal and laboratory experiments, studies on androgen deprivation therapy patients, and studies on testosterone-treated patients. We finish by providing recommendations for the clinician and needs for future research.

Variations of plasma leptin in show horses during a work season

Leptin is an adipocytokine mainly expressed by adipose tissue. Secretion of leptin in healthy animals is closely related to fat mass and metabolic activity. The aim of this study was to investigate plasma leptin variations, in relation to nutritional and exercise parameters in adult show horses during a work season. EDTA-blood samples were taken at rest from 37 Iberian horses. Body weight, body condition score and fat percentage determined by ultrasonic measurement of rump fat thickness were measured. Plasma leptin was determined with a multi-species RIA kit. Linear mixed effects model was used to assess relationship between plasma leptin and other biological parameters. Plasma leptin concentration was <12.6 ng/ml (mean = 2.8 ± 1.6 ng/ml) and was significantly higher during training periods (p < 0.0001) (4.5 ± 1.7 ng/ml) than in show periods (2.0 ± 1.1 ng/ml), despite a significant increase (p < 0.0001) in energy intake. The body weight remained almost constant. The plasma leptin concentrations were significantly affected by exercise (p < 0.0001), body weight (p = 0.04) and BCS (p < 0.0001), but were not affected by percentage of fat. In conclusion, the marked decrease in leptin values observed during a period of intense (i.e. excessive) exercise could result from an adaptation to cumulative alterations in energy balance, to exercise per se or to a combination of both.

Increased adiposity in DNA binding-dependent androgen receptor knockout male mice associated with decreased voluntary activity and not insulin resistance

In men, as testosterone levels decrease, fat mass increases and muscle mass decreases. Increased fat mass in men, in particular central obesity, is a major risk factor for type 2 diabetes, cardiovascular disease, and all-cause mortality. Testosterone treatment has been shown to decrease fat mass and increase fat-free mass. We hypothesize that androgens act directly via the DNA binding-dependent actions of the androgen receptor (AR) to regulate genes controlling fat mass and metabolism. The aim of this study was to determine the effect of a global DNA binding-dependent (DBD) AR knockout (DBD-ARKO) on the metabolic phenotype in male mice by measuring body mass, fat mass, food intake, voluntary physical activity, resting energy expenditure, substrate oxidation rates, serum glucose, insulin, lipid, and hormone levels, and metabolic gene expression levels and second messenger protein levels. DBD-ARKO males have increased adiposity despite a decreased total body mass compared with wild-type (WT) males. DBD-ARKO males showed reduced voluntary activity, decreased food intake, increased serum leptin and adiponectin levels, an altered lipid metabolism gene profile, and increased phosphorylated CREB levels compared with WT males. This study demonstrates that androgens acting via the DNA binding-dependent actions of the AR regulate fat mass and metabolism in males and that the increased adiposity in DBD-ARKO male mice is associated with decreased voluntary activity, hyperleptinemia and hyperadiponectinemia and not with insulin resistance, increased food intake, or decreased resting energy expenditure.

Effect of 12 months of testosterone replacement therapy on metabolic syndrome components in hypogonadal men: data from the Testim Registry in the US (TRiUS)

BACKGROUND

Recent evidence suggests that there may be a bidirectional, physiological link between hypogonadism and metabolic syndrome (MetS), and testosterone replacement therapy (TRT) has been shown to improve some symptoms of MetS in small patient populations. We examined the effect of 12 months of TRT on MetS components in a large cohort of hypogonadal men.

METHODS

Data were obtained from TRiUS (Testim® Registry in the United States), a 12-month, multicenter, prospective observational registry (N = 849) of hypogonadal men prescribed Testim 1% testosterone gel (5-10 g/day). Data analyzed included age, total testosterone (TT), free testosterone (FT), sex hormone-binding globulin (SHBG), and MetS components: waist circumference, blood pressure, fasting blood glucose, plasma triglycerides, and HDL cholesterol.

RESULTS

Of evaluable patients (581/849) at baseline, 37% were MetS+ (n = 213) and 63% were MetS- (n = 368). MetS+ patients had significantly lower TT (p < 0.0001) and SHBG (p = 0.01) levels. Patients with the lowest quartile TT levels (<206 ng/dL [<7.1 nmol/L]) had a significantly increased risk of MetS+ classification vs those with highest quartile TT levels (≥331 ng/dL [≥11.5 nmol/L]) (odds ratio 2.66; 95% CI, 1.60 to 4.43). After 12 months of TRT, TT levels significantly increased in all patients (p < 0.005). Despite having similar TT levels after TRT, only MetS+ patients demonstrated significant decreases in waist circumference, fasting blood glucose levels, and blood pressure; lowest TT quartile patients demonstrated significant decreases in waist circumference and fasting blood glucose. Neither HDL cholesterol nor triglyceride levels changed significantly in either patient population.

CONCLUSION

Hypogonadal MetS+ patients were more likely than their MetS- counterparts to have lower baseline TT levels and present with more comorbid conditions. MetS+ patients and those in the lowest TT quartile showed improvement in some metabolic syndrome components after 12 months of TRT. While it is currently unclear if further cardiometabolic benefit can be seen with longer TRT use in this population, testing for low testosterone may be warranted in MetS+ men with hypogonadal symptoms.

Relations of adiponectin to levels of metabolic parameters and sexual hormones in elderly type 2 diabetic patients

BACKGROUND

Despite the effective role of adiponectin levels in the predisposition to type 2 diabetes mellitus, the potential impact of adiponectin in manifest type 2 diabetes is less studied.

OBJECTIVES

This study aimed to determine gender-specific differences regarding the relationship between adiponectin levels and metabolic parameters as well as sex hormones in elderly type 2 diabetics.

METHODS

Sixty-two elderly type 2 diabetic men (mean age 60 [9] years) and 38 postmenopausal type 2 diabetic women (mean age 64 [9] years) were evaluated in a cross-sectional study. Glycemic control, lipids, sex hormones, adiponectin, and anthropometric parameters were measured in all participants.

RESULTS

Serum adiponectin was higher in women than in men (P < 0.006). After controlling for age and body mass index, adiponectin concentrations showed a positive correlation with sex hormone-binding globulin and high-density lipoprotein levels (P < 0.001) and a negative correlation with glycated hemoglobin, homeostasis model assessment index for insulin resistance, glucose, C-peptide, and triglyceride levels (P < 0.05) in all patients. In men, adiponectin significantly correlated with serum levels of testosterone (r = 0.420; P < 0.002). In women, negative correlations were observed between adiponectin levels and the fatty liver index (r = -0.492; P < 0.006) and γ-glutamyltransferase (r = -0.432; P < 0.01).

CONCLUSIONS

High serum adiponectin is a feature of better metabolic control and lipid profile, whereas low adiponectin levels are associated with fatty liver disease in women and low testosterone levels in men with type 2 diabetes.

Update: Hypogonadotropic hypogonadism in type 2 diabetes and obesity

Studies over the last few years have clearly established that at least 25% of men with type 2 diabetes have subnormal free testosterone concentrations in association with inappropriately low LH and FSH concentrations. Another 4% have subnormal testosterone concentrations with elevated LH and FSH concentrations. The Endocrine Society, therefore, now recommends the measurement of testosterone in patients with type 2 diabetes on a routine basis. The subnormal testosterone concentrations are not related to glycosylated hemoglobin or duration of diabetes, but are associated with obesity, very high C-reactive protein concentrations, and mild anemia. In addition, subnormal testosterone concentrations in these men are associated with a two to three times elevated risk of cardiovascular events and death in two early studies. Short-term studies of testosterone therapy in hypogonadal men with type 2 diabetes have demonstrated an increase in insulin sensitivity and a decrease in waist circumference. However, the data on the effect of testosterone replacement on glycemic control and cardiovascular risk factors such as cholesterol and C-reactive protein concentrations are inconsistent. As far as sexual function is concerned, testosterone treatment increases libido but does not improve erectile dysfunction and thus, phosphodiesterase inhibitors may be required. Trials of a longer duration are clearly required to definitively establish the benefits and risks of testosterone replacement in patients with type 2 diabetes and low testosterone.

Inflammatory markers in population studies of aging

PURPOSE

To review findings from major epidemiologic studies regarding risk factors for and consequences of elevated markers of inflammation in older adults.

RESULTS

Most large, current epidemiologic studies of older adults have measured serum interleukin-6 (IL-6), C-reactive protein (CRP) and tumor necrosis factor alpha (TNF-alpha) and some studies also include more extensive batteries of measures including soluble receptors. There are few defined risk factors for the modest elevations in inflammatory markers seen with aging. These include visceral adiposity, lower sex steroid hormones, smoking, depression and periodontal disease. Of the markers assessed, IL-6 is most robustly associated with incident disease, disability and mortality.

CONCLUSION

Though correlated with age, the etiology of elevated inflammatory markers remains incompletely defined. Inflammation, especially IL-6 may be a common cause of multiple age-related diseases or a final common pathway by which disease leads to disability and adverse outcomes in older adults. Future research targeting inflammation should examine these pathways.

Endogenous testosterone, endothelial dysfunction, and cardiovascular events in men with nondialysis chronic kidney disease

BACKGROUND AND OBJECTIVES

Deterioration of kidney function impairs testosterone production, with hypogonadism being common in men with chronic kidney disease (CKD). In nonrenal populations, testosterone is suggested to participate in the atherosclerotic process. In male dialysis patients, we showed that low testosterone increases the risk of mortality. We here studied plausible links among testosterone levels, vascular derangements, and cardiovascular events in nondialysis CKD men.

DESIGN, SETTING, PARTICIPANTS, & METHODS

This was a cross-sectional analysis in which flow-mediated dilation (FMD) was assessed in 239 CKD male patients (stages 1 to 5; mean age 52 ± 12 years), together with routine measurements, serum total and free testosterone, and follow-up for cardiovascular outcomes.

RESULTS

Total and free testosterone levels decreased in parallel with the reduction of kidney function. Multiple regression analyses showed that total and free testosterone significantly and independently contributed to explain the variance of FMD. After a median follow-up of 31 months (range 8 to 35 months), 22 fatal and 50 nonfatal cardiovascular events occurred. In Cox analysis, the risk of cardiovascular events was reduced by 22% for each nanomole-per-liter increment of total testosterone. This reduced risk persisted after adjustment for age, renal function, diabetes mellitus, previous cardiovascular history, C-reactive protein, albumin, and FMD. The same was true for free testosterone concentrations.

CONCLUSIONS

The reduction in endogenous testosterone levels observed with progressive CKD was inversely associated with endothelial dysfunction and exacerbated the risk of future cardiovascular events in nondialysis male CKD patients.

Mitochondrial DNA polymerase editing mutation, PolgD257A, reduces the diabetic phenotype of Akita male mice by suppressing appetite

Diabetes and the development of its complications have been associated with mitochondrial DNA (mtDNA) dysfunction, but causal relationships remain undetermined. With the objective of testing whether increased mtDNA mutations exacerbate the diabetic phenotype, we have compared mice heterozygous for the Akita diabetogenic mutation (Akita) with mice homozygous for the D257A mutation in mitochondrial DNA polymerase gamma (Polg) or with mice having both mutations (Polg-Akita). The Polg-D257A protein is defective in proofreading and increases mtDNA mutations. At 3 mo of age, the Polg-Akita and Akita male mice were equally hyperglycemic. Unexpectedly, as the Polg-Akita males aged to 9 mo, their diabetic symptoms decreased. Thus, their hyperglycemia, hyperphagia and urine output declined significantly. The decrease in their food intake was accompanied by increased plasma leptin and decreased plasma ghrelin, while hypothalamic expression of the orexic gene, neuropeptide Y, was lower and expression of the anorexic gene, proopiomelanocortin, was higher. Testis function progressively worsened with age in the double mutants, and plasma testosterone levels in 9-mo-old Polg-Akita males were significantly reduced compared with Akita males. The hyperglycemia and hyperphagia returned in aged Polg-Akita males after testosterone administration. Hyperglycemia-associated distal tubular damage in the kidney also returned, and Polg-D257A-associated proximal tubular damage was enhanced. The mild diabetes of female Akita mice was not affected by the Polg-D257A mutation. We conclude that reduced diabetic symptoms of aging Polg-Akita males results from appetite suppression triggered by decreased testosterone associated with damage to the Leydig cells of the testis.

Increase in visceral and subcutaneous abdominal fat in men with prostate cancer treated with androgen deprivation therapy

OBJECTIVE

Androgen deprivation therapy (ADT) for prostate cancer is associated with increases in fat mass and risk of type 2 diabetes; however, the relationship between sex steroid deficiency and abdominal fat distribution remains controversial.

DESIGN

We conducted a 12-month prospective observational study at a tertiary referral centre.

PATIENTS AND MEASUREMENTS

We investigated changes in abdominal fat distribution and insulin resistance in 26 men (70.6±6.8 years) with nonmetastatic prostate cancer during the first year of ADT.

RESULTS

Twelve months of ADT increased visceral abdominal fat area by 22% (from 160.8±61.7 to 195.9±69.7 cm(2) ; P<0.01) and subcutaneous abdominal fat area by 13% (from 240.7±107.5 to 271.3±92.8 cm(2) ; P<0.01). Fat mass increased by 14% (+3.4 kg; P<0.001) and lean tissue mass decreased by 3.6% (-1·9 kg; P<0.001). Insulin resistance (HOMA-IR) increased by 12% (2.50±1.12 to 2.79±1.31, P<0.05). There was no change in fasting glucose or glycated haemoglobin levels. Total testosterone (TT) was inversely associated with visceral fat area independent of oestradiol (E2), but E2 was not associated with visceral fat area independent of TT. Visceral fat area, not TT or E2, was independently associated with insulin resistance.

CONCLUSIONS

ADT for prostate cancer results in accumulation of both visceral and subcutaneous abdominal fat. Increased visceral fat area appears more closely linked to testosterone than oestradiol deficiency. Increased insulin resistance may arise secondary to visceral fat accumulation, rather than as a direct result of sex steroid deficiency.

Serum concentrations of high-molecular weight adiponectin and their association with sex steroids in premenopausal women

At present, the association between adiponectin and sex hormones in women is controversial. Recent studies suggest that it is high-molecular weight (HMW) adiponectin and the HMW to total adiponectin ratio rather than total adiponectin that are associated with antiatherogenic activities, insulin sensitivity, metabolic syndrome, and prediction of cardiovascular events. The present study aimed to investigate whether measuring HMW adiponectin and the HMW to total adiponectin ratio rather than total adiponectin might be more useful to detect an association between circulating female sex steroids and adipocytokines. In a clinical trial, we investigated the associations of total adiponectin, HMW adiponectin, and the HMW to adiponectin ratio with several androgens and estradiol in 36 healthy premenopausal women with regular cycles. No association between the investigated sex hormones and adiponectin was observed. The HMW adiponectin was negatively correlated with estradiol after adjustment for age and body mass index. The HMW to total adiponectin ratio was significantly negatively associated with testosterone, free testosterone, and androstenedione. The testosterone to estradiol ratio, as a parameter for the estrogen-androgen balance, was not associated with adiponectin or the HMW isoform. In conclusion, there is a negative association between estradiol and HMW adiponectin, and between testosterone, free testosterone, and androstenedione and the HMW to adiponectin ratio. Thus, one mechanism whereby female sex steroids may influence the cardiovascular risk of women could be alteration of the relationship between HMW and total adiponectin concentrations in plasma.

Efficacy and safety of two different testosterone undecanoate formulations in hypogonadal men with metabolic syndrome

AIM

To investigate efficacy and safety of two different preparations of testosterone undecanoate (TU) in 52 hypogonadal men [mean age 57 yr and mean testosterone (T) < 320 ng/dl] with metabolic syndrome (MS).

SUBJECTS AND METHODS

Randomized, double-blind, double-dummy study with three parallel treatment arms [oral TU; transdermal placebo gel (P); im TU] administration for 12 months (mo). Each subject was randomized (1:1:3) to receive either oral TU (2 capsules of 40 mg/twice per day at breakfast and dinner, equalling a total dose of 160 mg/day; no.=10) for 6 mo and continued with im TU for further 6 mo, or P (3-4 g/day; no.=10) and im TU (1000 mg/12 weeks from week 6; no.=32) for 12 mo.

RESULTS

After 6 mo, im TU increased T and free- T levels (p<0.0001), and improved metabolic parameters [reduction in Homeostasis Model Assessment (HOMA) index, p<0.0001; waist circumference and fat mass, p<0.001, respectively], in International Index of Erectile Function-5 and Aging Males' Symptoms scores (p<0.01, respectively). After 12 months, im TU produced further increases in T and free- T levels (p<0.0001) and metabolic parameters (reduction in HOMA-index, p<0.0001; waist circumference p<0.0001; fat mass, p<0.001). No major adverse event due to T treatment occurred.

CONCLUSIONS

Clinical efficacy of T replacement therapy in hypogonadal men with MS is reached when its plasmatic levels approach into the medium-high range of normality (>5 ng/ml), although subjective threshold values may be different. Administration of im TU was more effective than oral TU to reach the target for T levels and to improve MS parameters. TU was safe over 12 months and discontinuation rates were similar to placebo.

Maternal deprivation has sexually dimorphic long-term effects on hypothalamic cell-turnover, body weight and circulating hormone levels

Maternal deprivation (MD) has numerous outcomes, including modulation of neuroendocrine functions. We previously reported that circulating leptin levels are reduced and hypothalamic cell-turnover is affected during MD, with some of these effects being sexually dimorphic. As leptin modulates the development of hypothalamic circuits involved in metabolic control, we asked whether MD has long-term consequences on body weight, leptin levels and the expression of neuropeptides involved in metabolism. Rats were separated from their mother for 24h starting on postnatal day (PND) 9 and sacrificed at PNDs 13, 35 and 75. In both sexes MD reduced body weight, but only until puberty, while leptin levels were unchanged at PND 35 and significantly reduced at PND 75. Adiponectin levels were also reduced at PND 75 in females, while testosterone levels were reduced in males. At PND 13, MD modulated cell-turnover markers in the hypothalamus of males, but not females and increased nestin, a marker of immature neurons, in both sexes, with males having higher levels than females and a significantly greater rise in response to MD. There was no effect of MD on hypothalamic mRNA levels of the leptin receptor or metabolic neuropeptides or the mRNA levels of leptin and adiponectin in adipose tissue. Thus, MD has long-term effects on the levels of circulating hormones that are not correlated with changes in body weight. Furthermore, these endocrine outcomes are different between males and females, which could be due to the fact that MD may have sexually dimorphic effects on hypothalamic development.

Effects of testosterone supplementation on markers of the metabolic syndrome and inflammation in hypogonadal men with the metabolic syndrome: the double-blinded placebo-controlled Moscow study

OBJECTIVE

Men with the metabolic syndrome (MetS) have low plasma testosterone (T) levels. The aim of this study was to establish whether the normalization of plasma T improves the features of the MetS.

DESIGN

A randomized, placebo-controlled, double-blinded, phase III trial of 184 men suffering from both the MetS and hypogonadism.

PATIENTS

One hundred and eighty-four men, aged 35-70, with the MetS and hypogonadism (baseline total T level <12·0 nm or calculated free T level <225 pm.), recruited in the outpatient andrology and urology clinic, Research Center for Endocrinology in Moscow, Russia.

INTERVENTION

Treatment for 30 weeks with either parenteral T undecanoate (n = 113; TU; 1000 mg IM) or placebo (n = 71), administered at baseline, and after 6 and 18 weeks. One hundred and five (92·9%) men receiving TU and 65 (91·5%) receiving placebo completed the trial.

MEASUREMENTS

Body weight, body mass index (BMI), waist circumference (WC), hip circumference, waist-to-hip ratio, insulin, leptin, glucose, cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, C-reactive protein (CRP), interleukin-1-beta (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10) and tumour necrosis factor-alpha (TNF-α).

RESULTS

There were significant decreases in weight, BMI and WC in the TU vs placebo group. Levels of leptin and insulin also decreased, but there were no changes in serum glucose or lipid profile. Of the inflammatory markers, IL-1β, TNF-α and CRP decreased, while IL-6 and IL-10 did not change significantly.

CONCLUSIONS

Thirty weeks of T administration normalizing plasma T in hypogonadal men with the MetS improved some components of the MetS and a number of inflammatory markers.

Testosterone and the metabolic syndrome

Metabolic syndrome and testosterone deficiency in men are closely Linked. Epidemiological studies have shown that Low testosterone Levels are associated with obesity, insulin resistance and an adverse Lipid profile in men. Conversely in men with metabolic syndrome and type 2 diabetes have a high prevalence of hypogonadism. Metabolic syndrome and Low testosterone status are both independently associated with increased all-cause and cardiovascular mortality. Observational and experimental data suggest that physiological replacement of testosterone produces improvement in insulin resistance, obesity, dyslipidae-mia and sexual dysfunction along with improved quality of Life. However, there are no Long-term interventional studies to assess the effect of testosterone replacement on mortality in men with Low testosterone Levels. This article reviews the observational and interventional clinical data in relation to testosterone and metabolic syndrome.

Effects of testosterone on Type 2 diabetes and components of the metabolic syndrome

Observations from clinical studies suggest that low serum levels of testosterone in men are often associated with obesity, insulin resistance, and metabolic compromise. Indeed, the clinical symptoms of late-onset hypogonadism are markedly similar to those of Type 2 diabetes mellitus (T2DM) and metabolic syndrome, and may share a similar pathophysiology. Observational and experimental data suggest that testosterone treatment improves a number of hallmark features of T2DM and metabolic syndrome, namely insulin resistance, obesity, dyslipidemia, and sexual dysfunction. Consequently, clinical studies have been undertaken to assess the impact of testosterone-replacement therapy in this patient group. The present article reviews the observational clinical data suggesting an association between low serum testosterone and metabolic impairment, the clinical data relating to the effects of testosterone treatment on components of the metabolic syndrome, and the randomized clinical trails that have formally investigated whether testosterone-replacement therapy provides clinical benefit to hypogonadal men with T2DM and/or metabolic syndrome.

Testosterone deficiency: a risk factor for cardiovascular disease?

Male gender is a major risk factor for premature cardiovascular death, a relationship not yet explained. Low testosterone in men is a risk factor for the metabolic syndrome and type 2 diabetes and is associated independently with individual components of the metabolic syndrome--visceral obesity, insulin resistance, hyperglycemia, hypertension and dyslipidemia. Epidemiological studies report increased mortality in men with low testosterone. Testosterone replacement in the short-term reduces waist circumference, cholesterol and circulating pro-inflammatory cytokines and improves insulin sensitivity and glycemic control in diabetics. Testosterone also has beneficial effects on cardiac ischemia, angina and chronic heart failure. This manuscript reviews the current evidence supporting a link between low testosterone and cardiovascular disease, highlighting the need for larger, longer-term studies.

The role of testosterone in type 2 diabetes and metabolic syndrome in men

Over the last three decades, it has become apparent that testosterone plays a significant role in glucose homeostasis and lipid metabolism. The metabolic syndrome is a clustering of risk factors predisposing to diabetes mellitus type 2, atherosclerosis and cardiovascular morbidity and mortality. The main components of the syndrome are visceral obesity, insulin resistance, glucose intolerance, raised blood pressure and dyslipidemia (elevated triglycerides, low levels of high-density lipoprotein cholesterol), and a pro-inflammatory and thrombogenic state. Cross-sectional epidemiological studies have reported a direct correlation between plasma testosterone and insulin sensitivity, and low testosterone levels are associated with an increased risk of type 2 diabetes mellitus, dramatically illustrated by androgen deprivation in men with prostate carcinoma. Lower total testosterone and sex hormone-binding globulin (SHBG) predict a higher incidence of the metabolic syndrome. There is evidence that hypotestosteronemia should be an element in the definition of the metabolic syndrome since low levels of testosterone are associated with or predict the development of the metabolic syndrome and of diabetes mellitus. Administration of testosterone to hypogonadal men reverses part of the unfavorable risk profile for the development of diabetes and atherosclerosis. So far, studies on the effects of normalization of testosterone in hypogonadal men on glucose homeostasis are limited, but convincing, and if diabetes mellitus is viewed in the context of the metabolic syndrome, the present results of testosterone treatment are very encouraging.

Prevalence and clinical implications of testosterone deficiency in men with end-stage renal disease

BACKGROUND

Abnormally low serum testosterone levels were recently associated with an increased mortality risk in male dialysis patients. However, the prevalence of testosterone deficiency in end-stage renal disease (ESRD) is not well defined. We hereby explore the prevalence and correlates of clinical testosterone deficiency in a large cohort of ESRD male patients.

METHODS

Two hundred and sixty ESRD men [median age 59 (25th-75th percentile 48-67)  years] were included. Testosterone concentration and testosterone deficiency (<10 nmol/L) were studied in relation to clinically evident cardiovascular disease and markers of inflammation at baseline as well as deaths registered during the following 36 months.

RESULTS

Testosterone deficiency was present in 44% of the patients, while 33% showed testosterone insufficiency (10-14 nmol/L), and only 23% had normal testosterone values (>14 nmol/L). Testosterone was strongly and inversely correlated to inflammatory markers (CRP, IL-6 and fibrinogen), even after correction for age and sex hormone-binding globulin. In a crude spline curve, low testosterone concentrations were associated with worse outcome. A clinical condition of testosterone deficiency was independently associated with cardiovascular co-morbidity [odds ratio (OR) 2.51; 95% confidence interval (CI) 1.32-4.76] and death (OR 2.00; 95% CI 1.01-3.97) in logistic regression analyses.

CONCLUSIONS

Testosterone deficiency is a common finding among male ESRD patients, and it is independently associated with inflammation, cardiovascular co-morbidity and outcome. Future studies are needed to determine the potential adverse effects of male hypogonadism in ESRD and the possibility of improving risk profile, quality of life, and ultimately outcome with testosterone supplementation in these patients.

Associations among hypogonadism, C-reactive protein, symptom burden, and survival in male cancer patients with cachexia: a preliminary report

CONTEXT

Cachexia is characterized by muscle wasting, anorexia, and elevated inflammatory markers. In patients without cancer, hypogonadism is associated with lower lean body mass, increased symptom burden, and decreased survival. Hypogonadism in cancer cachexia could exacerbate symptoms, facilitate a proinflammatory state, and decrease survival.

OBJECTIVES

To explore the relationships among these factors, a retrospective study of male cancer patients was conducted.

METHODS

The charts of 98 consecutive male patients referred to a cachexia clinic at a comprehensive cancer center were reviewed. All patients reported weight loss of >5% within the preceding six months; the median age was 60 years. Fifty-seven (58%) had serum C-reactive protein (CRP), and 68 (69%) had total testosterone evaluated. Symptoms were evaluated by the Edmonton Symptom Assessment Scale.

RESULTS

Median CRP was 20mg/L, and median testosterone level was 185 ng/dL (6.42 nmol/L) (normal > or = 240 ng/dL or 8.36 nmol/L). There was an inverse correlation between testosterone and CRP levels (P<0.01). Lower testosterone was associated with increased dyspnea and insomnia (P<0.05). Poor appetite and insomnia (P<0.05) correlated with elevated CRP. Survival of patients with testosterone levels < or = 185 ng/dL (6.42 nmol/L) was decreased compared with that of those with levels >185 ng/dL (13 vs. 62 weeks, P=0.004). Patients with CRP levels >10mg/L had decreased survival compared with those with levels < or = 10mg/L (15 vs. 46 weeks, P=0.01). The combination of hypogonadism and elevated CRP was associated with poorer prognosis. Elevated CRP levels were associated with increased symptom burden and decreased survival. Low testosterone was associated with decreased survival and correlated inversely with CRP levels, dyspnea, and insomnia.

CONCLUSION

Our preliminary results suggest that testosterone and CRP may be additive or synergistic as markers for survival in male patients and could be useful in future prognostic models.

Association of sex hormones and C-reactive protein levels in men

OBJECTIVES

The age-associated decline in sex hormone levels in men is paralleled by an increase in cardiovascular disease and associated risk factors including low grade chronic inflammation. The objective of this analysis was to investigate the association between sex hormone levels and C-reactive protein (CRP) in a population-based sample of men.

DESIGN

Population-based, cross-sectional observational survey.

PARTICIPANTS

A multistage stratified design was used to recruit a random sample of 2301 racially and ethnically diverse men age 30-79 years. Blood samples were obtained on 1899 men. Analyses were conducted on 1559 men with complete data on CRP and sex hormone levels.

MEASUREMENTS

High-sensitivity CRP levels. The association between CRP and sex hormone levels was assessed using multiple linear regression models.

RESULTS

An inverse association was observed, in both bivariate and multivariate analyses, between CRP and total testosterone, free testosterone and SHBG levels. These associations remained statistically significant after adjusting for age, body mass index, comorbid conditions and lifestyle factors. A positive trend between oestradiol (total and free) and CRP levels was not statistically significant.

CONCLUSIONS

A robust, inverse dose-response correlation between testosterone and SHBG levels with CRP levels provides further evidence of a potential role of androgens in inflammatory processes.

Association of body fat with C-reactive protein in rheumatoid arthritis

OBJECTIVE

The serum C-reactive protein (CRP) concentration is commonly used in rheumatoid arthritis (RA) as a surrogate marker of systemic inflammation, presumably induced by synovitis. However, other tissues, such as adipose tissue, can induce CRP production. This study was undertaken to explore the associations between measures of adiposity and CRP levels in RA.

METHODS

One hundred ninety-six men and women with RA underwent anthropometric assessment and total body dual-energy x-ray absorptiometry for measurement of total and regional body fat and lean mass. The associations between measures of fat and lean mass and serum levels of CRP and interleukin-6 (IL-6) were determined in analyses stratified by sex, with adjustment for pertinent demographic, lifestyle, and RA disease and treatment covariates as well as for the potential modifying effects of articular activity and biologic pharmacotherapeutic agents.

RESULTS

All measures of adiposity were significantly associated with the level of CRP in women, but not in men. In women, the measure of adiposity that showed the strongest association with the CRP level was truncal fat, in which, in adjusted analyses, each kilogram increase was associated with a 0.101-unit increase in the logarithmically transformed CRP level (P < 0.001). Neither the level of articular activity nor the use of biologic agents significantly modified this association in women. However, in men, elevated articular involvement was associated with a decreasing CRP level as truncal fat increased. For all analyses, substitution of IL-6 for CRP produced similar findings.

CONCLUSION

Adiposity is independently associated with CRP levels in women with RA, and thus may confound the estimation of RA disease activity when serum CRP concentration is used as a surrogate for systemic inflammation.

Effect of sex hormone treatment on circulating adiponectin and subforms in Turner and Klinefelter syndrome

BACKGROUND

Sex hormones have been shown to influence levels of adiponectin. Furthermore, testosterone has been shown to alter the subform distribution of adiponectin, whereas the effects of oestradiol are equivocal. We investigated the impact of sex hormone replacement therapy (HRT) on circulating adiponectin and its subforms, fasting lipids and measures of insulin sensitivity in Turner syndrome (TS) and Klinefelter syndrome (KS) respectively.

MATERIALS AND METHODS

We compared eight young TS patients on and off 2 months of HRT vs. eight age- and body mass index (BMI) matched healthy females as well as 19 untreated KS patients vs. 20 testosterone treated KS patients vs. 20 age and BMI matched healthy males. Total adiponectin and adiponectin subforms separated by fast protein liquid chromatography were measured using an in-house assay. In addition, fasting levels of insulin, glucose and homeostasis model assessment estimates were determined.

RESULTS

In TS, total adiponectin levels were 10.5 +/- 3.1 (mean +/- SD) vs. 12.8 +/- 3.5 mg L(-1) (P = 0.02) and high molecular weight (HMW) adiponectin 5.8 +/- 2.7 and 6.8 +/- 1.9 mg L(-1) (P = 0.02) on and off HRT respectively. Irrespective of HRT, total adiponectin and HMW adiponectin were similar to control values. In KS, total adiponectin levels were 6.5 (3.0-24.2) (median and range) and 9.3 (4.3-14.3) mg L(-1) (P = NS) and HMW adiponectin was 2.5 (0.5-16.0) and 4.6 (1.3-8.6) mg L(-1) (P = NS) with and without testosterone treatment respectively, and similar to controls.

CONCLUSION

Short time HRT suppressed HMW and total adiponectin levels in TS patients. Testosterone treatment in KS patients had no effect on these parameters. In both groups of patients either adiponectin or the HMW subform seems to play no greater role in reflecting or mediating insulin sensitivity. Our data indicates that in patients with TS and KS, sex hormones have different effects on circulating adiponectin and its HMW subform than previously reported in other sex hormone deficient patients and healthy subjects.

Sex hormone-binding globulin as an independent predictor of incident type 2 diabetes mellitus in men

BACKGROUND

Low levels of sex hormone-binding globulin (SHBG) and total testosterone (T) in men have been associated with increased risk of type 2 diabetes mellitus (T2DM). As total T and SHBG levels are highly correlated, we determined whether SHBG influences the risk of T2DM through T or whether SHBG is an independent predictor of T2DM.

METHODS

Longitudinal analyses were conducted on men participating in the Massachusetts Male Aging Study, a population-based study of men aged 40-70 years. Of 1,709 men enrolled in 1987-1989, 1,156 were evaluated 7-10 years later and 853 after 15-17 years. Analyses were restricted to 1,128 men without T2DM at baseline.

RESULTS

Ninety new cases of T2DM were identified. After adjustment for age, body mass index, hypertension, smoking, alcohol intake, and physical activity, the hazard ratio (HR) for incident T2DM was 2.0 for each 1 SD decrease in SHBG (95% confidence interval [CI], 1.42-2.82, p < .001) and 1.29 for each 1 SD decrease in total T (95% CI, 1.01-1.66, p = .04). Free T was not associated with T2DM (HR = 1.03, 95% CI, 0.81-1.31, p = .79). The strong association of T2DM risk with SHBG persisted even after additional adjustment for free T (HR = 2.04, 95% CI, 1.44-2.87, p < .0001) or total T (HR = 1.95, 95% CI, 1.34-2.82, p = .0004).

CONCLUSIONS

SHBG is an independent predictor of incident T2DM even after adjusting for free T or total T. Free T is not significantly associated with T2DM. SHBG may contribute to the risk of T2DM through nonandrogenic mechanisms, which should be investigated as they may provide novel targets for diabetes prevention.

Transcriptional and post-translational regulation of adiponectin

Adiponectin is an adipose-tissue-derived hormone with anti-diabetic, anti-atherogenic and anti-inflammatory functions. Adiponectin circulates in the bloodstream in trimeric, hexameric and high-molecular-mass species, and different forms of adiponectin have been found to play distinct roles in the regulation of energy homoeostasis. The serum levels of adiponectin are negatively correlated with obesity and insulin resistance, yet the underlying mechanisms remain elusive. In the present review, we summarize recent progress made on the mechanisms regulating adiponectin gene transcription, multimerization and secretion. We also discuss the potential relevance of these studies to the development of new clinical therapy for insulin resistance, Type 2 diabetes and other obesity-related metabolic disorders.

Diabetes and skeletal health

Osteoporosis and diabetes affect a large proportion of the elderly population. The prevalence of diabetes and osteoporosis is increasing. Compared with individuals without diabetes, both men and women with diabetes have a higher risk of fractures, particularly at the hip, with consequent significant morbidity and mortality. Type 1 diabetes is associated with decreased bone mass and although bone mass data for Type 2 diabetes may or may not be decreased, there is evidence of altered bone quality in diabetes. The mechanisms involved include effects of insulin, insulin-like growth factor 1, cytokines, advanced glycation end products, and altered calcium homeostasis. In addition, a drug-induced increase in the incidence of fractures has been noted with the use of thiazolidinediones (TZDs). TZDs improve insulin sensitivity and have multitude other beneficial effects. Osteoblasts and adipocytes are derived from a common multipotential mesenchymal stem cell progenitor, with activation of peroxisome proliferator-activated receptor γ2 by both currently available TZDs (i.e. rosiglitazone and pioglitazone) stimulating adipogenesis and inhibiting osteoblastogenesis. The use of both rosiglitazone and pioglitazone is associated with an increased fracture risk, with changes in bone turnover markers and decreased bone mineral density.

Testosterone deficiency, insulin resistance and the metabolic syndrome

Changing lifestyles and an excess of food supply in developed countries have resulted in an increasing prevalence of overweight and obesity. As a consequence, a disorder of complex pathophysiology involving visceral adipose tissue as an endocrine organ, dyslipidemia, insulin resistance and hypertension has emerged-the so-called metabolic syndrome. This disorder can lead to the manifestation of type 2 diabetes mellitus and cardiovascular disease. In men, testosterone deficiency may contribute to the development of the metabolic syndrome. In turn, states of hyperinsulinemia and obesity lead to a reduction of testicular testosterone production. Testosterone has reciprocal effects on the generation of muscle and visceral adipose tissue by influencing the commitment of pluripotent stem cells and by inhibiting the development of preadipocytes. Insulin sensitivity of muscle cells is increased by augmenting mitochondrial capacity and fostering expression of oxidative phosphorylation genes. Testosterone has a protective effect on pancreatic beta cells, which is possibly exerted by androgen-receptor-mediated mechanisms and influence of inflammatory cytokines. As some, but not all, epidemiological and interventional studies indicate, testosterone substitution might be helpful in preventing or attenuating the metabolic syndrome in aging men with late-onset hypogonadism and in hypogonadal patients with type 2 diabetes mellitus, but larger controlled trials are needed to confirm such hypotheses.

Safety and efficacy of testosterone gel in the treatment of male hypogonadism

Transdermal testosterone gels were first introduced in the US in 2000. Since then, they have emerged as a favorable mode of testosterone substitution. Serum testosterone levels reach a steady-state in the first 24 hours of application and remain in the normal range for the duration of the application. This pharmacokinetic profile is comparable to that of testosterone patch but superior to injectable testosterone esters that are associated with peaks and troughs with each dose. Testosterone gels are as efficacious as patches and injectable forms in their effects on sexual function and mood. Anticipated increases in prostate-specific antigen with testosterone therapy are not significantly different with testosterone gels, and the risk of polycythemia is lower than injectable modalities. Application site reactions, a major drawback of testosterone patches, occur less frequently with testosterone gels. However, inter-personal transfer is a concern if appropriate precautions are not taken. Superior tolerability and dose flexibility make testosterone gel highly desirable over other modalities of testosterone replacement. Androgel and Testim, the two currently available testosterone gel products in the US, have certain brand-specific properties that clinicians may consider prior to prescribing.

Biochemical hypogonadism in men with type 2 diabetes in primary care practice

Objective:

This study explores the links between testosterone deficiency and Quality Outcomes Framework (QOF) parameters in three south Staffordshire practices prior to a major double-blind placebo-controlled intervention study. Research design and methods:

Four hundred and eighty-eight consecutive type 2 diabetic patients, aged over 18, attending their general practitioner for routine diabetes visits were assessed for sex hormone binding globulin, total testosterone (TT), calculated free testosterone (FT) and bioavailable testosterone, glycated haemoglobin A1c (HbA1c), body mass index, waist circumference, blood pressure, lipid profile, Sexual Health Inventory for Men, and current and past prescriptions for erectile dysfunction (ED).

Results:

TT and FT were significantly inversely associated with raised body mass index, waist circumference and HbA1C. The prevalence of ED was 77%, which was associated with low levels of TT, FT and raised HbA1C. Only 10% were receiving treatment for ED.

Conclusions:

Patients with low testosterone were more likely to fall outside the QOF targets and new markers might be difficult to achieve unless low testosterone is addressed. There is a strong case for the inclusion of TT and FT estimation in routine diabetic care.

Sex steroid hormones in diabetes-induced sexual dysfunction: focus on the female gender

INTRODUCTION

Diabetes is associated with gender-specific changes in sex steroid hormones. However, the mechanisms responsible for these associations as well as the link to sexual dysfunction are not well understood.

AIM

To discuss key clinical and laboratory findings linking diabetes, sex steroid hormones, and sexual dysfunction, with particular focus on the female gender.

METHODS

A comprehensive literature review was conducted using the PubMed database. Search terms were used in appropriate combinations, including diabetes, insulin, insulin sensitivity, androgen, estrogen, sexual function, women, men, estrogen receptor, and androgen receptor. Over 400 citations were selected, based on topical relevance, and examined for study methodology and major findings.

MAIN OUTCOME MEASURES

Data from peer-reviewed publications.

RESULTS

Imbalances in sex steroid hormone levels are strongly associated with diabetes and this may negatively impact upon sexual function. Although numerous factors are likely to contribute to the development of diabetes and its complications, the role of sex steroid hormones must be acknowledged.

CONCLUSIONS

Research related to diabetic women and sexual dysfunction is severely lacking. Identifying underlying causes for a given hormonal imbalance in diabetic patients, as well as determination of genetic and age-dependent factors, will become important in identifying the subpopulations in which hormonal replacement regimens will be most effective. Investigation into treating diabetic patients with adjunct hormonal therapies or steroid hormone receptor modulators holds much promise.

Statin therapy is associated with lower total but not bioavailable or free testosterone in men with type 2 diabetes

OBJECTIVE

There is a high prevalence of hypogonadism in men with type 2 diabetes. This will lead to an increase in assessments of hypogonadism. Statins could potentially decrease testosterone levels by reducing the availability of cholesterol for androgen synthesis. We compared testosterone levels and hypogonadal symptoms with statin use in a cross-sectional study of 355 men with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Total testosterone, sex hormone-binding globulin (SHBG), and estradiol were measured by an enzyme-linked immunosorbent assay. Bioavailable testosterone was measured by the modified ammonium sulfate precipitation method. Free testosterone was calculated using Vermeulen's formula. Symptoms of hypogonadism were assessed using the Androgen Deficiency in the Aging Male questionnaire.

RESULTS

Statins were associated with lower total testosterone (11.9 vs. 13.4 nmol/l, P = 0.006) and a trend toward lower SHBG (29.4 vs. 35.3 nmol/l, P = 0.034) compared with no treatment. Bioavailable testosterone, free testosterone, estradiol, and hypogonadal symptoms were not affected. Subanalysis showed that atorvastatin was associated with reduced total testosterone (11.4 vs. 13.4 nmol/l, P = 0.006) and a trend toward reduced SHBG (27.6 vs. 35.3 nmol/l, P = 0.022) compared with no treatment, and there was an apparent dose-response effect with the lowest levels of total testosterone seen in men treated with >or=20 mg atorvastatin (9.6 nmol/l, P = 0.017). Simvastatin use was not associated with significant reductions in testosterone or SHBG levels.

CONCLUSIONS

Assessing androgen status using total testosterone in men with type 2 diabetes treated with statins, particularly atorvastatin, may potentially lead to diagnostic error. Levels of bioavailable testosterone or free testosterone are recommended for the assessment of hypogonadism in this group if total testosterone levels are borderline.

Low testosterone and anaemia in men with type 2 diabetes

OBJECTIVE

Anaemia is frequently found in patients with diabetes, in whom it is associated with increased morbidity and mortality. Low testosterone levels are also common in men with type 2 diabetes. We hypothesized that low testosterone levels are also associated with anaemia in men with type 2 diabetes, over the effects of chronic kidney disease.

DESIGN

Cross-sectional cohort study, performed in 2005 in a tertiary diabetes clinic. Patients 464 men with type 2 diabetes.

MAIN OUTCOME MEASURE

Anaemia (haemoglobin (Hb) < 13.7 g/dl in men aged < 60, or < 13.2 g/dl in men aged 60 and older).

RESULTS

About 24% of study participants had anaemia, which was associated with the presence and severity of chronic kidney disease, systemic inflammation, increased age, and reduced iron availability. In addition, testosterone levels were independently associated with reduced Hb levels, determining between 6 and 8% of the total variability in raw Hb levels in this population after adjusting for these other factors. Individuals with total testosterone level < 10 nmol/l (43% of the cohort) were more likely to have anaemia (adjusted odds ratio 1.7; 95% CI 1.1-2.8). Similarly, anaemia was twice as common in individuals with a calculated free testosterone of < 0.23 nmol/l (adjusted odds ratio 2.0, 95% CI 1.2-3.1).

CONCLUSIONS

These findings suggest that testosterone deficiency may contribute to the increased frequency of anaemia in men with type 2 diabetes. However, the appropriate clinical response to testosterone deficiency in anaemic patients remains to be established by prospective clinical trials.