Testosterone therapy and bone quality in men with diabetes and hypogonadism: Study design and protocol

Testosterone replacement in men with sexual dysfunction

BACKGROUND

Clinical practice guidelines recommend testosterone replacement therapy (TRT) for men with sexual dysfunction and testosterone deficiency. However, TRT is commonly promoted in men without testosterone deficiency and existing trials often do not clearly report participants' testosterone levels or testosterone-related symptoms. This review assesses the potential benefits and harms of TRT in men presenting with complaints of sexual dysfunction.

OBJECTIVES

To assess the effects of testosterone replacement therapy compared to placebo or other medical treatments in men with sexual dysfunction.

SEARCH METHODS

We performed a comprehensive search of CENTRAL (the Cochrane Library), MEDLINE, EMBASE, and the trials registries ClinicalTrials.gov and World Health Organization International Clinical Trials Registry Platform, with no restrictions on language of publication or publication status, up to 29 August 2023.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) in men (40 years or over) with sexual dysfunction. We excluded men with primary or secondary hypogonadism. We compared testosterone or testosterone with phosphodiesterase-5 inhibitors (PDEI5I) to placebo or PDE5I alone.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the literature, assessed the risk of bias, extracted data, and rated the certainty of evidence (CoE) according to GRADE using a minimally contextualized approach. We performed statistical analyses using a random-effects model and interpreted them according to standard Cochrane methodology. Predefined primary outcomes were self-reported erectile dysfunction assessed by a validated instrument, sexual quality of life assessed by a validated instrument, and cardiovascular mortality. Secondary outcomes were treatment withdrawal due to adverse events, prostate-related events, and lower urinary tract symptoms (LUTS). We distinguished between short-term (up to 12 months) and long-term (> 12 months) outcomes.

MAIN RESULTS

We identified 43 studies with 11,419 randomized participants across three comparisons: testosterone versus placebo, testosterone versus PDE5I, and testosterone with PDE5I versus PDE5I alone. This abstract focuses on the most relevant comparison of testosterone versus placebo. Testosterone versus placebo (up to 12 months) Based on a predefined sensitivity analysis of studies at low risk of bias, and an analysis combing data from the similar International Index of Erectile Function (IIEF-EF) and IIEF-5 instruments, TRT likely results in little to no difference in erectile function assessed with the IIEF-EF (mean difference (MD) 2.37, 95% confidence interval (CI) 1.67 to 3.08; I² = 0%; 6 RCTs, 2016 participants; moderate CoE) on a scale from 6 to 30 with larger values reflecting better erectile function. We assumed a minimal clinically important difference (MCID) of greater than or equal to 4. TRT likely results in little to no change in sexual quality of life assessed with the Aging Males' Symptoms scale (MD -2.31, 95% CI -3.63 to -1.00; I² = 0%; 5 RCTs, 1030 participants; moderate CoE) on a scale from 17 to 85 with larger values reflecting worse sexual quality of life. We assumed a MCID of greater than or equal to 10. TRT also likely results in little to no difference in cardiovascular mortality (risk ratio (RR) 0.83, 95% CI 0.21 to 3.26; I² = 0%; 10 RCTs, 3525 participants; moderate CoE). Based on two cardiovascular deaths in the placebo group and an assumed MCID of 3%, this would correspond to no additional deaths per 1000 men (95% CI 1 fewer to 4 more). TRT also likely results in little to no difference in treatment withdrawal due to adverse events, prostate-related events, or LUTS. Testosterone versus placebo (later than 12 months) We are very uncertain about the longer-term effects of TRT on erectile dysfunction assessed with the IIEF-EF (MD 4.20, 95% CI -2.03 to 10.43; 1 study, 42 participants; very low CoE). We did not find studies reporting on sexual quality of life or cardiovascular mortality. We are very uncertain about the effect of testosterone on treatment withdrawal due to adverse events. We found no studies reporting on prostate-related events or LUTS.

AUTHORS' CONCLUSIONS

In the short term, TRT probably has little to no effect on erectile function, sexual quality of life, or cardiovascular mortality compared to a placebo. It likely results in little to no difference in treatment withdrawals due to adverse events, prostate-related events, or LUTS. In the long term, we are very uncertain about the effects of TRT on erectile function when compared to placebo; we did not find data on its effects on sexual quality of life or cardiovascular mortality. The certainty of evidence ranged from moderate (signaling that we are confident that the reported effect size is likely to be close to the true effect) to very low (indicating that the true effect is likely to be substantially different). The findings of this review should help to inform future guidelines and clinical decision-making at the point of care.

One-Year Mean A1c of > 7% is Associated with Poor Bone Microarchitecture and Strength in Men with Type 2 Diabetes Mellitus

INTRODUCTION

Type 2 diabetes mellitus (T2DM) is associated with normal or slightly elevated bone mineral density (BMD) but paradoxically increased fracture risk. Although multiple mechanisms have been proposed to explain this observation, one thing is clear from prior studies, T2DM is associated with poor bone quality rather than a defect in bone quantity. The objective of our study is to evaluate the effect of longitudinal glycemic control on bone quality and bone turnover in men with T2DM.

METHODS

This was a secondary analysis of baseline data from 169 male participants, aged 35-65 in 3 clinical trials. Participants were grouped according to the average of all their A1C measurements between 9 and 15 months prior to study entry (group 1: no T2DM, group 2: T2DM with A1C ≤ 7%, group 3: T2DM with A1C > 7%). At study entry serum osteocalcin and C-terminal telopeptide of type 1 collagen (CTx) were measured by ELISA, and testosterone and estradiol by liquid-chromatography/mass-spectrometry. Areal BMD, trabecular bone score and body composition were measured by dual-energy X-ray absorptiometry while volumetric BMD, bone microarchitecture, and bone strength were assessed by high-resolution peripheral quantitative computed tomography.

RESULTS

At the tibia, trabecular separation was higher and trabecular number was significantly lower in group 3 compared to both groups 2 and 1, even after adjustments for covariates (p = 0.02 for both). Bone strength indices at the tibia such as stiffness and failure load were lowest in group 3, the difference being significant when compared to group 1 (p = 0.01, p = 0.009 respectively) but not to group 2, after adjustments for covariates. Bone turnover markers (osteocalcin and CTx) were significantly lower in group 3 relative to group 1, with CTx also being significantly lower in group 3 compared with group 2 (p < 0.001, p = 0.001 respectively).

CONCLUSION

Poor glycemic control over the course of a year in men with T2DM is associated with poorer bone microarchitecture and strength, and reduced bone turnover. Conversely, good glycemic control in the setting of T2DM appears to attenuate this observed impairment in bone quality.

Circulating osteogenic progenitors and osteoclast precursors are associated with long-term glycemic control, sex steroids, and visceral adipose tissue in men with type 2 diabetes mellitus

INTRODUCTION

Type 2 diabetes mellitus (T2DM) is well-known to be associated with normal bone density but, concurrently, low bone turnover and increased risk for fracture. One of the proposed mechanisms is possible derangement in bone precursor cells, which could be represented by deficiencies in circulating osteogenic progenitor (COP) cells and osteoclast precursors (OCP). The objective of our study is to understand whether extent of glycemic control has an impact on these cells, and to identify other factors that may as well.

METHODS

This was a secondary analysis of baseline data from 51 male participants, aged 37-65 in an ongoing clinical trial at Michael E. DeBakey VA Medical Center, Houston, Texas, USA. At study entry serum Hemoglobin A1c was measured by high-performance liquid chromatography osteocalcin (OCN) and C-terminal telopeptide of type 1 collagen (CTx) were measured by ELISA, and testosterone and estradiol by liquid-chromatography/mass-spectrometry. Areal bone mineral density (BMD), trabecular bone score and body composition were measured by dual energy x-ray absorptiometry, while COP and OCP were measured by flow cytometry.

RESULTS

When adjusted for serum testosterone, parathyroid hormone, and 25-hydroxyvitamin D, those with poor long-term glycemic control had significantly higher percentage of COP (p = 0.04). COP correlated positively with visceral adipose tissue (VAT) volume (r = 0.37, p = 0.01) and negatively with free testosterone (r = -0.28, p = 0.05) and OCN (r = -0.28, p = 0.07), although only borderline for the latter. OCP correlated positively with age, FSH, lumbar spine BMD, and COP levels, and negatively with glucose, triglycerides, and free estradiol. Multivariable regression analyses revealed that, in addition to being predictors for each other, another independent predictor for COP was VAT volume while age, glucose, and vitamin D for OCP.

CONCLUSION

Our results suggest that high COP could be a marker of poor metabolic control. However, given the complex nature and the multitude of factors influencing osteoblastogenesis/adipogenesis, it is possible that the increase in COP is a physiologic response of the bone marrow to increased osteoblast apoptosis from poor glycemic control. Alternatively, it is also likely that a metabolically unhealthy profile may retard the development of osteogenic precursors to fully mature osteoblastic cells.

Testosterone Therapy Effects on Bone Mass and Turnover in Hypogonadal Men with Type 2 Diabetes

CONTEXT

Male hypogonadism is associated with low bone mineral density (BMD) and increased fragility fracture risk. Patients with type 2 diabetes (T2D) have relatively higher BMD, but greater fracture risk.

OBJECTIVE

Evaluate the skeletal response to testosterone therapy in hypogonadal men with T2D compared with hypogonadal men without T2D.

METHODS

Single arm, open-label clinical trial (NCT01378299) involving 105 men (40-74 years old), with average morning testosterone <300 ng/dL. Subjects were injected intramuscularly with testosterone cypionate (200 mg) every 2 weeks for 18 months. Testosterone and estradiol were assessed by liquid chromatography/mass spectrometry; serum C-terminal telopeptide of type I collagen (CTX), osteocalcin and sclerostin by enzyme-linked immunosorbent assay; glycated hemoglobin (HbA1c) by high-performance liquid chromatography, areal BMD (aBMD) and body composition by dual-energy x-ray absorptiometry; tibial volumetric BMD (vBMD) and bone geometry by peripheral quantitative computed tomography.

RESULTS

Among our population of hypogonadal men, 49 had T2D and 56 were non-T2D. After 18 months of testosterone therapy, there were no differences in circulating testosterone and estradiol between the groups. Hypogonadal men with T2D had increased osteocalcin, reflecting increased osteoblast activity, compared with non-T2D men (P < .01). T2D men increased lumbar spine aBMD (P < .05), total area at 38% tibia (P < .01) and periosteal and endosteal circumferences at the same site (P < .01 for both). T2D men had reduced tibial vBMD (P < .01), but preserved bone mineral content (P = .01). Changes in HbA1c or body composition were similar between the 2 groups.

CONCLUSION

Testosterone therapy results in greater improvements in the skeletal health of hypogonadal men with T2D than their nondiabetic counterparts.