A possible new risk factor in diabetic patients with erectile dysfunction: homocysteinemia

Risk factors for erectile dysfunction in diabetes mellitus: a systematic review and meta-analysis

Background

Previous studies have established that diabetes mellitus (DM) markedly raises the risk of developing erectile dysfunction (ED). Despite extensive investigations, the risk factors associated with ED in diabetic men have yet to be unequivocally determined, owing to incongruent and inconclusive results reported in various studies.

Objective

The objective of this systematic review and meta-analysis was to assess the risk factors for ED in men with DM.

Methods

A comprehensive systematic review was conducted, encompassing studies published in the PubMed, Scopus and Embase databases up to August 24th, 2023. All studies examining the risk factors of ED in patients with DM were included in the analysis. To identify significant variations among the risk factors, odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were employed. The risk of bias was evaluated using the Newcastle-Ottawa Scale(NOS) for longitudinal studies and the Agency for Healthcare Research and Quality Scale(AHRQ) for cross-sectional studies.

Results

A total of 58 studies, including a substantial participant pool of 66,925 individuals diagnosed with DM, both with or without ED, were included in the meta-analysis. Mean age (OR: 1.31, 95% CI=1.24-1.37), smoking status (OR: 1.32, 95% CI=1.18-1.47), HbA1C (OR: 1.44, 95% CI=1.28-1.62), duration of DM (OR: 1.39, 95% CI=1.29-1.50), diabetic neuropathy (OR: 3.47, 95% CI=2.16-5.56), diabetic retinopathy (OR: 3.01, 95% CI=2.02-4.48), diabetic foot (OR: 3.96, 95% CI=2.87-5.47), cardiovascular disease (OR: 1.92, 95% CI=1.71-2.16), hypertension (OR: 1.74, 95% CI=1.52-2.00), microvascular disease (OR: 2.14, 95% CI=1.61-2.85), vascular disease (OR: 2.75, 95% CI=2.35-3.21), nephropathy (OR: 2.67, 95% CI=2.06-3.46), depression (OR: 1.82, 95% CI=1.04-3.20), metabolic syndrome (OR: 2.22, 95% CI=1.98-2.49), and diuretic treatment (OR: 2.42, 95% CI=1.38-4.22) were associated with increased risk factors of ED in men with DM.

Conclusion

Our study indicates that in men with DM, several risk factors for ED have been identified, including mean age, HbA1C, duration of DM, diabetic neuropathy, diabetic retinopathy, diabetic foot, cardiovascular disease, hypertension, microvascular disease, vascular disease, nephropathy, depression, metabolic syndrome, and diuretic treatment. By clarifying the connection between these risk factors and ED, clinicians and scientific experts can intervene and address these risk factors, ultimately reducing the occurrence of ED and improving patient management.

Correlation between erectile dysfunction and serum B12 levels: a 136-case cross-sectional analysis

BACKGROUND

Erectile dysfunction (ED) involves the inability to initiate or sustain penile erection with sufficient hardness to ensure satisfying sexual relations. Many causes are blamed in the etiology.

OBJECTIVES

In this study, the correlation between serum vitamin B12 (vit B12) levels with ED was researched in a homogeneous case group after exclusion of all other predisposing conditions causing ED.

METHODS

The study included male patients attending the urology clinic from 2015 to 2022. Patients were prospectively registered to the study. Cases were divided into two groups as low and normal according to vit B12 levels. In the study, vit B12 levels ≤200 mg/dL were accepted as low. The Sexual Health Inventory for Men-5 (SHIM-5) was used to assess the erectile function. The SHIM-5 scores for the groups were compared. All patients with comorbid diseases, medication use, or previous surgical history predisposing toward ED and organic and/or psychogenic causes for ED were excluded from the study.

RESULTS

The study included 136 patients abiding by the study criteria among 957 patients. The mean age of cases was 63.35 ± 7.83 years. Mean vit B12 value was 320.74 ± 184.74 mg/dL and 32 cases (23.5%) had inadequate vit B12 (< 200 mg/dL). The mean SHIM-5 value in the group was 15.48 ± 6.71. In the inadequate vit B12 and normal vit B12 groups, the mean SHIM-5 values were 15.30 ± 6.85 and 16.06 ± 6.28, respectively, with no significant difference between the two groups (t = 0.562, p = 0.575). Vit B12 deficiency was identified in 26.7% of patients with sexual desire disorder (SDD) (n = 90) and 17.4% of those without SDD (X2 = 1.46, p = 0.228).

DISCUSSION

Contrary to the general trend in the literature, we found no significant correlation between vit B12 levels and ED.

CONCLUSION

There is a need for prospective randomized controlled studies for detailed analysis of the correlation between erectile dysfunction and vit B12.

Hyperhomocysteinemia: Focus on Endothelial Damage as a Cause of Erectile Dysfunction

Erectile Dysfunction (ED) is defined as the inability to maintain and/or achieve a satisfactory erection. This condition can be influenced by the presence of atherosclerosis, a systemic pathology of the vessels that also affects the cavernous arteries and which can cause an alteration of blood flow at penile level. Among the cardiovascular risk factors affecting the genesis of atherosclerosis, hyperhomocysteinemia (HHcys) plays a central role, which is associated with oxidative stress and endothelial dysfunction. This review focuses on the biological processes that lead to homocysteine-induced endothelial damage and discusses the consequences of HHcys on male sexual function

Human tissue kallikrein-1 protects against the development of erectile dysfunction in a rat model of hyperhomocysteinemia

The aim of this study was to investigate the mechanism by which a diet inducing high hyperhomocysteinemia (HHcy) leads to the deterioration of erectile function in rats and whether this is inhibited by expression of the human tissue kallikrein-1 (hKLK1) gene. We established a rat model of HHcy by feeding methionine (Met)-rich diets to male Sprague-Dawley (SD) rats. Male wild-type SD rats (WTRs) and transgenic rats harboring the hKLK1 gene (TGRs) were fed a normal diet until 10 weeks of age. Then, 30 WTRs were randomly divided into three groups as follows: the control (n = 10) group, the low-dose (4% Met, n = 10) group, and the high-dose (7% Met, n = 10) group. Another 10 age-matched TGRs were fed the high-dose diet and designated as the TGR+7% Met group. After 30 days, in all four groups, erectile function was measured and penile tissues were harvested to determine oxidative stress, endothelial cell content, and penis fibrosis. Compared with the 7% Met group, the TGR+7% Met group showed diminished HHcy-induced erectile dysfunction (ED), indicating the improvement caused by hKLK1. Regarding corpus cavernosum endothelial cells, hKLK1 preserved endothelial cell-cell junctions and endothelial cell content, and activated protein kinase B/endothelial nitric oxide synthase (Akt/eNOS) signaling. Fibrosis assessment indicated that hKLK1 preserved normal penis structure by inhibiting apoptosis in the corpus cavernosum smooth muscle cells. Taken together, these findings showed that oxidative stress, impaired corpus cavernosum endothelial cells, and severe penis fibrosis were involved in the induction of ED by HHcy in rats, whereas hKLK1 preserved erectile function by inhibiting these pathophysiological changes.

Melatonin Treatment Ameliorates Hyperhomocysteinemia-Induced Impairment of Erectile Function in a Rat Model

BACKGROUND

Hyperhomocysteinemia (HHcy) has been reported to be strongly correlated with the occurrence of erectile dysfunction (ED), but the mechanisms are not fully understood. Moreover, whether melatonin could be a potential treatment of HHcy-induced ED needs to be elucidated.

AIM

The aim of this study was to investigate the effects of melatonin on HHcy-induced ED and the potential mechanisms via modulating oxidative stress and apoptosis.

METHODS

The Sprague-Dawley (SD) rat model of HHcy was induced by 7% methionine (Met)-rich diets. 36 male SD rats were randomly distributed into 3 groups (n = 12 per group): control group, 7% Met group, and 7% Met + melatonin (Mel; 10 mg/kg, intraperitoneal injection) treatment group. After 4 weeks, the erectile function of all rats was evaluated by electrical stimulation of the cavernous nerve. Histologic and molecular alterations of the corpus cavernosum were also analyzed by immunofluorescence, immunohistochemistry, enzyme-linked immunosorbent assay, Western blotting, and polymerase chain reaction.

OUTCOMES

HHcy-induced ED rat models were successfully established, and Mel could preserve erectile function mainly through inhibiting oxidative stress via the Erk1/2/Nrf2/HO-1 signaling pathway and suppression of apoptosis.

RESULTS

Erectile function was significantly reduced in the rats with HHcy compared with that in the control group and was ameliorated in the HHcy rats treated with Mel. Compared with the control group, the rats in the HHcy group showed the following: (1) higher levels of total plasma homocysteine; (2) fewer neuronal nitric oxide synthase-positive cells in the corpus cavernous; (3) higher levels of reactive oxygen species and malondialdehyde, higher expression levels of nicotinamide adenine dinucleotide phosphate oxidase, and lower activities of superoxide dismutase, indicating an overactivated oxidative stress; (4) lower expression levels of Erk1/2/Nrf2/HO-1 signaling pathway components; and (5) higher levels of apoptosis, as determined by the expression levels of Bax, Bcl-2, and caspase 3. Mel treatment improved the erectile response, as well as histologic and molecular alterations.

CLINICAL TRANSLATION

Our study on a rodent model of HHcy provided evidence that Mel could be a potential therapeutic method for HHcy-related ED.

CONCLUSIONS

Mel treatment improves erectile function in rats with HHcy probably by potential antioxidative stress activity. This finding provides evidence for a potential new therapy for HHcy-induced ED. Tang Z, Song J, Yu, Z, et al. Melatonin Treatment Ameliorates Hyperhomocysteinemia-Induced Impairment of Erectile Function in a Rat Model. J Sex Med 2019;16:1506-1517.

Folic acid supplementation improves erectile function in patients with idiopathic vasculogenic erectile dysfunction by lowering peripheral and penile homocysteine plasma levels: a case-control study

BACKGROUND

Erectile dysfunction (ED) has common risk factors with many cardiovascular (CV) impairments. In view of these facts, hyperhomocysteinemia (HHcys) has been postulated for involvement in endothelial dysfunction.

OBJECTIVES

We evaluated peripheral and penile homocysteine (Hcys) plasma levels before and after folic acid supplementation in idiopathic vasculogenic erectile dysfunction (ED) patients.

MATERIALS AND METHODS

This study included 50 consecutive patients and 50 consecutive healthy controls that were recruited from December 2017 to December 2018. The patients received folic acid (FA) daily for 3 months and were evaluated by the abridged 5-item International Index of Erectile Function (IIEF-5) and penile duplex before and after therapy, in addition to plasma Hcys levels.

RESULTS

Our study showed improvement in the severity of ED in our patients as all of them became mild to moderate ED after folic acid administration. Additionally, the median scores of IIEF-5 significantly increased from 6 to 14, respectively (p < 0.001). Furthermore, the median peripheral and penile Hcys plasma levels (μmol/l) significantly decreased after folic acid administration as 39 patients with moderate ED and 11 patients with severe ED were 0.62, 0.34, 5.37, 0.37, respectively, became mild to moderate ED with their median peripheral and penile Hcys plasma levels became 0.19, 0.15, p < 0.001, <0.001, respectively. Peripheral Hcys level correlates significantly with penile Hcys before and after folic acid administration (r: -0.06 p: 0.8, r: 0.9, p < 0.001, respectively).

DISCUSSION AND CONCLUSION

Recently, an emerging body of evidence suggests a role for Hcys and folate in erectile function. Interestingly, our interventional study is one of the first that evaluated the effect of folic acid supplementation on HHcys where it demonstrated a significant decrease in peripheral and penile Hcys plasma levels after folic acid administration. Thus, FA should be prescribed concomitantly with phosphodiesterase type 5 inhibitors in ED patients.

Serum Homocysteine Levels in Men with and without Erectile Dysfunction: A Systematic Review and Meta-Analysis

OBJECTIVES

Elevated levels of serum homocysteine (Hcy) have been associated with cardiovascular diseases and endothelial dysfunction, conditions closely associated with erectile dysfunction (ED). This meta-analysis was aimed to assess serum Hcy levels in subjects with ED compared to controls in order to clarify the role of Hcy in the pathogenesis of ED.

METHODS

Medline, Embase, and the Cochrane Library were searched for publications investigating the possible association between ED and Hcy. Results were restricted by language, but no time restriction was applied. Standardized mean difference (SMD) was obtained by random effect models.

RESULTS

A total of 9 studies were included in the analysis with a total of 1320 subjects (489 subjects with ED; 831 subjects without ED). Pooled estimate was in favor of increased Hcy in subjects with ED with a SMD of 1.00, 95% CI 0.65-1.35, p < 0.0001. Subgroup analysis based on prevalence of diabetes showed significantly higher SMD in subjects without diabetes (1.34 (95% CI 1.08-1.60)) compared to subjects with diabetes (0.68 (95% CI 0.39-0.97), p < 0.0025 versus subgroup w/o diabetes).

CONCLUSIONS

Results from our meta-analysis suggest that increased levels of serum Hcy are more often observed in subjects with ED; however, increase in Hcy is less evident in diabetic compared to nondiabetic subjects. This study is registered with Prospero registration number CRD42018087558.

Treatment with GLP1 receptor agonists reduce serum CRP concentrations in patients with type 2 diabetes mellitus: A systematic review and meta-analysis of randomized controlled trials

AIM

To undertake a systematic review and meta-analysis of randomized controlled trials of the effect of glucagon-like peptide-1 receptor agonist (GLP-1 RAs) therapy on serum C-reactive protein (CRP) concentrations.

METHOD

PubMed-Medline, SCOPUS, Web of Science and Google Scholar databases were searched for the period up until March 16, 2016. Prospective studies evaluating the impact of GLP-1 RAs on serum CRP were identified. A random effects model (using the DerSimonian-Laird method) and generic inverse variance methods were used for quantitative data synthesis. Sensitivity analysis was conducted using the leave-one-out method. Heterogeneity was quantitatively assessed using the I² index. Random effects meta-regression was performed using unrestricted maximum likelihood method to evaluate the impact of potential moderator. International Prospective Register for Systematic Reviews (PROSPERO) number CRD42016036868.

RESULTS

Meta-analysis of the data from 7 treatment arms revealed a significant reduction in serum CRP concentrations following treatment with GLP-1 RAs (WMD -2.14 (mg/dL), 95% CI -3.51, -0.78, P=0.002; I² 96.1%). Removal of one study in the meta-analysis did not change the result in the sensitivity analysis (WMD -2.14 (mg/dL), 95% CI -3.51, -0.78, P=0.002; I² 96.1%), indicating that our results could not be solely attributed to the effect of a single study. Random effects meta-regression was performed to evaluate the impact of potential moderator on the estimated effect size. Changes in serum CRP concentration were associated with the duration of treatment (slope -0.097, 95% CI -0.158, -0.042, P<0.001).

CONCLUSIONS

This meta-analysis suggests that GLP-1 RAs therapy causes a significant reduction in CRP.

Demethylation treatment restores erectile function in a rat model of hyperhomocysteinemia

Methylation modification is an important cellular mechanism of gene expression regulation. Dimethylarginine dimethylaminohydrolase-2 (DDAH-2) protein is a pivotal molecular for endothelium function. To explore the effects of 5-aza-deoxycytidine (5-aza), a demethylation agent, in hyperhomocysteinemia (hhcy)-related erectile dysfunction (ED) rats, 5-aza (1 mg kg⁻¹) was administrated to Sprague-Dawley hhcy-rats induced by supplemented methionine chow diet. Erectile function, nitric oxide-cyclic guanosine monophosphate (NO-cGMP) levels, expression of DDAH-2 protein and promoter methylation status of DDAH-2 were studied in the corpora cavernosa. We found that supplemented methionine diet induced a high homocysteine level after 6 weeks of treatment. DDAH-2 protein was down-regulated in the corpora cavernosa while the administration of 5-aza up-regulated DDAH-2 expression and restored erectile function. The methionine-fed rats showed high methylation levels of DDAH-2 promoter region while the group treated with 5-aza demonstrated lower-methylation levels when compared to the methionine-fed group. Besides, the administration of 5-aza improved NO and cGMP levels in methionine-fed rats. Therefore, the methylation mechanism involves in ED pathogenesis, and demethylation offers a potential new strategy for ED treatment.

Elevated serum homocysteine level as an independent risk factor for erectile dysfunction: a prospective pilot case-control study

Homocysteine is an amino acid that is produced from the metabolic demethylation of dietary methionine. It has gained arising attention for its association with increased risk of myocardial infarction, stroke and venous thromboembolism. Erectile dysfunction (ED), especially for vasculogenic ED, is a vascular disorder of cavernosal vascular bed. In this prospective pilot case-control study, we investigated plasma homocysteine levels in 32 ED patients and 20 healthy control men. Related patients characteristics including age, weight, height, marital status, smoking and drinking status, level of education were collected and analysed as well as penile colour Doppler ultrasound parameters. ED patients were further categorised into mild, moderate and severe ED based on 5-item of the International Index of Erectile Function. Higher homocysteine levels were observed in ED patients as compared with controls (p < .05). A multivariate logistic regression with likelihood ratio test revealed that homocysteine and penile peak systolic blood flow velocity (PSV) levels posed significant indicators for ED (chi-square of likelihood ratio = 20.42, df = 2, p < .005) as well as moderate and severe ED occurrence (chi-square of likelihood ratio = 28.50, df = 2, p < .005). The threshold value of homocysteine concentration to discriminate ED and control subjects was 12.65 μmol/L by performing receiver operating characteristic curve analyses. These data suggested that elevation of homocysteine levels was associated with an increased risk of ED.

The potential physiological crosstalk and interrelationship between two sovereign endogenous amines, melatonin and homocysteine

The antioxidant melatonin and the non-proteinogenic excitotoxic amino acid homocysteine (Hcy) are very distinct but related reciprocally to each other in their mode of action. The elevated Hcy level has been implicated in several disease pathologies ranging from cardio- and cerebro-vascular diseases to neurodegeneration owing largely to its free radical generating potency. Interestingly, melatonin administration potentially normalizes the elevated Hcy level, thereby protecting the cells from the undesired Hcy-induced excitotoxicity and cell death. However, the exact mechanism and between them remain obscure. Through literature survey we have found an indistinct but a vital link between melatonin and Hcy i.e., the existence of reciprocal regulation between them, and this aspect has been thoroughly described herein. In this review, we focus on all the possibilities of co-regulation of melatonin and Hcy at the level of their production and metabolism both in basal and in pathological conditions, and appraised the potential of melatonin in ameliorating homocysteinemia-induced cellular stresses. Also, we have summarized the differential mode of action of melatonin and Hcy on health and disease states.

Effect of laparoscopic Roux-en-Y gastric bypass surgery on type 2 diabetes mellitus with hypertension: a randomized controlled trial

AIMS

The aim of this study was to evaluate the effect of laparoscopic Roux-en-Y gastric bypass (RYGB) surgery compared with usual care with and without Exenatide therapy in obese people with type 2 diabetes mellitus (T2DM) and hypertension.

METHODS

108 obese T2DM with hypertension were enrolled and randomly allocated to usual care (group A), usual care plus Exenatide (group B), and RYGB surgery (group C). Demographic characteristics, metabolic parameters and cardiac structure/function along with inflammatory cytokines were measured and compared before and after 12 months.

RESULTS

At 12 months, diabetes remission had occurred in no patients in groups A and B versus 90% in group C, and there was a significant decrease in requirement of antihypertensive drugs in group C compared with groups A and B (P<0.05). Other parameters (body mass index, hemoglobin A1c, homeostasis model assessment of insulin resistance, lipids), inflammation index (high sensitivity C-reactive protein, tumor necrosis factor-α, high molecular weight adiponectin) and cardiac structure (left ventricular mass index) were significantly improved in groups B and C, but patients in group C had the greatest degree of improvement (P<0.05).

CONCLUSION

RYGB surgery improves a number of parameters including cardiovascular function in obese hypertensive people with T2DM. This is likely to be due to, at least in part, an improvement in the abnormal metabolic panel and to reduced inflammation.

Biochemical and genetic markers of erectile dysfunction

Erectile dysfunction (ED) is a very common pathology, affecting over 150 million men worldwide. The pathogenesis is typically multifactorial, involving a kaleidoscope of organic, endocrine, and psychogenic factors. In general, ED is divided into organic and psychogenic impotence, but most men with organic etiologies have an associated psychogenic component. Given the high frequency of this pathology, the identification of biochemical and genetic correlates and/or markers is of pivotal interest not only for treating preciously these patients and preventing serious psychological consequences but also for the high risk for occult cardiovascular disease (CVD) that often accompanies or follows this pathology. A variety of cardiovascular risk factors have been associated with both the onset and the severity of ED, including markers of endothelial function, thrombosis, and especially dyslipidemia, so that their measurement should now be considered as an important part of the increased global cardiometabolic risk profile in patients with ED. While nitric oxide (NO), asymmetric dimethylarginine (ADMA), and endothelin (ET) hold some promises as biochemical markers of both CVD and ED, there are several technical and clinical drawbacks that make their measurement overall meaningless in the clinical practice. As regards genetic polymorphisms, controversial results have been provided so far. Although some genetic markers were consistently associated with ED, other studies failed to demonstrate significant associations, highlighting a substantial bias in standardization of methodologies and patient enrolment. Nevertheless, further research in this area should be encouraged, since the first promising evidence that gene therapy might be effective to restore the decline in ED has been provided in the animal model.

Prevalence of erectile dysfunction among Chinese men with type 2 diabetes mellitus

The aims of this study were to investigate the prevalence of ED in Chinese men with type 2 diabetes mellitus, and evaluate the efficacy and safety of sildenafil citrate in these patients. Patients from 42 outpatient diabetes clinics with type 2 diabetes mellitus and ED as defined by the International Index of Erectile Function (IIEF)-5 were studied. Participants with ED received three doses (100 mg each) of sildenafil citrate for use over 3 months. Efficacy of sildenafil citrate was assessed using the IIEF-5 and the Global Efficacy Questionnaire (GEQ). Adverse events were recorded by patients in a daily diary. A total of 5477 participants were evaluated, and 75.2% had ED. Age, duration of diabetes and glycosylated hemoglobin (HbA(1)c) >6.5% were independently and significantly associated with the presence and degree of ED. Patients who received pharmacotherapy (N=389) reported significant improvements. The rate of erections as determined by the GEQ was also significantly improved following treatment. ED is a common complication in Chinese men with type 2 diabetes mellitus, and certain risk factors are associated with the presence of ED and severity. Sildenafil citrate is a safe and effective treatment for these patients.

The endothelial-erectile dysfunction connection: an essential update

INTRODUCTION

The endothelial monolayer plays a crucial role in the vasodilation and hemodynamic events involved in erection physiology. Due to its relevant functions, a close link has been established between endothelial integrity and erectile dysfunction (ED). Endothelial dysfunction is induced by the detrimental actions of vascular risk factors (VRFs), identified as common correlates for the development of cardiovascular disease and ED. It is currently recognized that ED is the early harbinger of a more generalized vascular systemic disorder, and, therefore, an evaluation of endothelial health in ED patients should be of prime relevance. Several noninvasive methods for endothelial function assessment have been proposed, including the Penile Nitric Oxide Release Test (PNORT).

AIM

To highlight the most recent gathered knowledge on basic and clinical mechanisms underlying loss of cavernosal endothelial function promoted by VRFs and to discuss local and systemic methods for endothelial function assessment in ED individuals, focusing on the PNORT.

MAIN OUTCOME MEASURES

A complete revision on the novel basic and clinical links between endothelial and ED.

METHODS

A systematic review of the literature regarding the aforementioned issues.

RESULTS

Risk factor-associated cavernosal endothelial dysfunction is mostly induced by unifying mechanisms, including oxidative stress and impaired endothelial nitric oxide functional activities, which present clinically as ED. Several techniques to evaluate endothelial dysfunction were revised, with advantages and limitations debated, focusing on our detailed expertise using the PNORT method.

CONCLUSIONS

The established endothelial-erectile dysfunction connection was thoroughly revised, from basic mechanisms to the clinical importance of endothelial dysfunction assessment as diagnosis for generalized vascular disease. Further studies are required to disclose efficient approaches to repair disabled endothelium and both restore and prevent endothelial dysfunction.

Review type 2 diabetes mellitus and erectile dysfunction

INTRODUCTION

Diabetes mellitus (DM) is a major risk factor for the development of erectile dysfunction (ED). Although most diabetic ED cases are in patients with type 2 diabetes (T2DM), the majority of basic science studies examining mechanisms of diabetic ED have been conducted in animal models of type 1 diabetes.

AIM

Recently, however, clinical and laboratory-based studies have uncovered some key underlying factors of T2DM-associated ED, which we have compiled in this review of T2DM ED.

MAIN OUTCOME MEASURES

The outcomes discussed in this review include major mechanisms underlying T2DM, discussing both clinical and basic science studies.

METHODS

We conducted an extensive search of pertinent clinical and basic science literature using PUBMED.

RESULTS

Mechanisms causing ED in T2DM are multifactorial and often lead to resistance to current therapy. Systemic effects of hyperglycemia and hypogonadism contribute to the development of impaired vasodilatory signaling, smooth muscle cell hypercontractility, and veno-occlusive disorder in T2DM ED.

CONCLUSIONS

Understanding the different causes for ED in T2DM patients may allow targeted therapy for improved erectile function.