The presence of hypertension, smoking and higher waist circumference are associated with ED in diabetic men.2

Lower testosterone positively correlates with worsening IIEF (International Index of Erectile Function) in diabetic men.2 Not all PI3K inhibitor diabetic men with ED have testosterone deficiency but evidence shows that it is present in a significant number. NICE guidelines recommendation is to ‘review the issue of erectile dysfunction annually’.3 The European Association of Urology (EAU) guidelines on ED state that measurement of testosterone is a minimum requirement in the diagnostic evaluation.4 Penile Doppler ultrasound has shown that basal systolic velocity and dynamic peak velocity after administration of a phosphodiesterase type 5 (PDE-5) inhibitor are significantly

reduced in hypogonadal diabetic men when compared to eugonadal men with diabetes.5 Failure to respond to Selleckchem I-BET-762 sildenafil is associated with low testosterone in diabetes.6 Animal work has found that castration leads to reduction in vascular smooth muscle content in the corpus cavernosum, reduced elastic fibres and increased collagen in the tunica albuginea, fat deposition between the tunica and corpus cavernosum and reduced nerve sheath thickness in the cavernosal nerve.7 Epidemiological studies consistently report that men with type 2 diabetes have lower testosterone and higher oestradiol levels than healthy controls.8 Sex hormone binding globulin (SHBG) levels may be low or in the low normal range in some diabetic subjects. Testosterone bound to SHBG is considered to be biologically inactive. Importantly, studies have shown that the biologically active fractions of the total testosterone, i.e. measured

free and bioavailable (free + albumen bound) testosterone which are independent of SHBG, are low. Furthermore, there is a high prevalence of hypogonadism in diabetes: 17% with total testosterone below the normal range <8nmol/L with symptoms, and a further 26% with testosterone levels between 8–12nmol/L (borderline low), again with symptoms.9 Full investigation is required to determine the underlying cause for hypogonadism; classical causes of hypogonadism include Branched chain aminotransferase Klinefelter’s syndrome, haemochromatosis, pituitary tumours and other causes of hypopituitarism. Registry studies have reported that only 25% of men with Klinefelter’s are diagnosed in life and they may present with diabetes.10 In the absence of a classical aetiology then the hypogonadal state may be due to obesity, a chronic inflammatory state or aging, or a combination of these. Central fat deposits metabolise testosterone to oestradiol as well as secreting adipocytokines which inhibit the hypothalamic-pituitary-testicular axis.10 Gonadotrophin levels may be normal or low as a result of this mechanism.