Metabolic syndrome and endothelial dyfunction and associated high proportions of erectile dysfunction in men: Innocent bystanders or accessories to the crime?

Abstract

The clustering of insulin resistance, dysglycaemia, dyslipidaemia, hypertension and central obesity represent the major features of metabolic syndrome. These clusters of factors may share common aetiology and each of which is a risk factor for cardiovascular disease. The metabolic syndrome appears to affect between 10 and 25% of adult populations worldwide. Several studies have described the association between metabolic syndrome and diabetes and cardiovascular disease [ [1] Wild S.H. Byrne C.D. The Global burden of the metabolic syndrome and its consequences for diabetes and cardiovascular disease. in: Byrne C.D. Wild S. Metabolic Syndrome. Wiley & Sons Ltd., England2005: 1-32 Google Scholar ]. Recently, it was observed that there was an association between erectile dysfunction (ED) and the metabolic syndrome and associated abnormal endothelial function [ [2] Esposito K. Giugliano F. Martedi E. Feola G. Marfella R. D’Armiento M. et al. High proportions of erectile dysfunction in men with the metabolic syndrome. Diabetes Care. 2005; 28: 1201-1203 Crossref PubMed Scopus (218) Google Scholar ]. Erectile dysfunction is an important cause of decreased quality of life in men. Strong epidemiological evidence links the subsequent risk of erectile dysfunction to the presence of well-recognized risk factors for coronary heart disease, such as increased body weight, hypertension, and dyslipidemia. Some have suggested that a diagnosis of erectile dysfunction is a sentinel event that should prompt investigation for coronary heart disease in a symptomatic men [ [2] Esposito K. Giugliano F. Martedi E. Feola G. Marfella R. D’Armiento M. et al. High proportions of erectile dysfunction in men with the metabolic syndrome. Diabetes Care. 2005; 28: 1201-1203 Crossref PubMed Scopus (218) Google Scholar ]. Esposito et al. [ [2] Esposito K. Giugliano F. Martedi E. Feola G. Marfella R. D’Armiento M. et al. High proportions of erectile dysfunction in men with the metabolic syndrome. Diabetes Care. 2005; 28: 1201-1203 Crossref PubMed Scopus (218) Google Scholar ] showed that in men with the metabolic syndrome (n = 100) were matched with men of the control group for age (38.4 ± 3.3 years versus 37.9 ± 2.9 years) and BMI (26.9 ± 1.9 kg/m2 versus 26.6 ± 2.1 kg/m2). Compared with the control group, patients with the metabolic syndrome had an increased prevalence of erectile dysfunction (26.7% versus 13%, P = 0.03), reduced endothelial function score (6.3 ± 0.9 versus 9.5 ± 0.3, P = 0.01), and higher circulating concentrations of CRP (median [interquartile range] 1.7 [0.6–3.8] mg/l versus 0.6 [0.2–2.7] mg/l) [ [2] Esposito K. Giugliano F. Martedi E. Feola G. Marfella R. D’Armiento M. et al. High proportions of erectile dysfunction in men with the metabolic syndrome. Diabetes Care. 2005; 28: 1201-1203 Crossref PubMed Scopus (218) Google Scholar ]. Their results show a linear increment in the prevalence of erectile dysfunction that is associated with a linear increase in CRP level and a linear impairment of endothelial function score as the number of components of the metabolic syndrome increased. Moreover, the association between ED and endothelial function score supports the presence of some common vascular pathways underlying both conditions mediated through a pathway involving nitric oxide (NO) activity [ [3] Esposito K. Ciotola M. Giugliano F. De Sio M. Giugliano G. D’Armiento M. Giugliano D. Mediterranean diet improves erectile function in subjects with the metabolic syndrome. Int. J. Impot. Res. 2006; 18: 405-410 Crossref PubMed Scopus (119) Google Scholar ]. Moreover, erectile dysfunction in diabetic men correlates with endothelial dysfunction and endothelial activation [ [4] Saenz de Tejada I. Goldstein I. Azadzoi K. Krane R.J. Cohen R.A. Impaired neurogenic and endothelium-mediated relaxation of penile smooth muscle from diabetic men with impotence. N. Engl. J. Med. 1989; 320: 1025-1030 Crossref PubMed Scopus (765) Google Scholar ]. Interestingly enough, in study of 65 men with the metabolic syndrome; 35 out of them were assigned to the Mediterranean-style diet and 30 to the control diet. After 2 years, men on the Mediterranean diet consumed more fruits, vegetables, nuts, whole grain, and olive oil as compared with men on the control diet. Endothelial function score and inflammatory markers (C-reactive protein) improved in the intervention group, but remained stable in the control group. Mediterranean-style diet rich in whole grain, fruits, vegetables, legumes, walnut, and olive oil might be effective per se in reducing the prevalence of ED in men with the metabolic syndrome [ [5] De Angelis L. Marfella M.A. Siniscalchi M. Marino L. Nappo F. Giugliano F. et al. Erectile and endothelial dysfunction in type II diabetes: a possibile link. Diabetologia. 2001; 44: 1155-1160 Crossref PubMed Scopus (126) Google Scholar ]. It was estimated that around 30 million men in the USA and 100 million world wide may have ED [ [6] Lue TF Erectile dysfunction. N. Engl. J. Med. 2000; 342: 1802-1813 Crossref PubMed Scopus (1212) Google Scholar ]. Identifying new and potentially modifiable risk factors for ED is critical in order to devise effective, population-based preventive strategies. The impact of metabolic syndrome on the diabets, diabetes-related risks and cardiovascular disease is well established. The association of metabolic syndrome with ED may increase the burden not only on the health care systems but also on caring physician with regard to screening/surveillance strategies in this growing number of patients. This may add to the growing public health burden of metabolic syndrome and economic costs of this epidemic are enormous.