The aim of this study was to evaluate the ultrasound characteristics of the seminal vesicles (SVs) of infertile patients with diabetes mellitus (DM) and diabetic neuropathy (DN) and to investigate possible changes in ultrasound characteristics related to glycaemic control.To accomplish this,45 infertile patients with type 2 DM and symptomatic DN were selected.Twenty healthy fertile men and 20 patients with idiopathic oligoasthenoteratozoospermia without DM represented the control groups.DM patients were arbitrarily divided into three groups according to glycaemic control level (A=glycosylated haemoglobin ＜7％; B=glycosylated haemoglobin between 7％ and 10％; C=glycosylated haemoglobin ＞ 10％).Patients underwent prostate-vesicular transrectal ultrasonography and sperm analysis.The following SV ultrasound parameters were recorded:(i) body antero-posterior diameter (APD); (ii) fundus APD; (iii) parietal thicknesses of the right and left SVs; and (iv) the number of polycyclic areas within both SVs.We then calculated the following parameters:(i) fundus/body (F/B) ratio; (ii) difference of the parietal thickness between the right and the left SV; and (iii) pre-and post-ejaculatory APD difference.All DM patients had a higher F/B ratio compared to controls (P＜0.05).Group C had a higher F/B ratio compared to the other DM groups (P＜0.05).All DM patients had a lower pre-and post-ejaculatory difference of the body SV APD compared to controls (P＜0.05).Groups A and B had a similar pre-and post-ejaculatory difference of the body SV APD,whereas this difference was lower in Group C (P＜0.05).In conclusion,infertile DM patients with DN showed peculiar SV ultrasound features suggestive of functional atony,and low glycaemic control was associated with greater expression of these features.