Among patients with a chief complaint of lower urinary tract symptoms (LUTS), some patients present with diabetes mellitus (DM). In clinical practice, patients with DM who present with a chief complaint of LUTS are not usually suspected of having a neurogenic bladder due to DM unless they have complications such as retinopathy or neuropathy due to DM, but 75–100% of patients with DM are reported to have urodynamic abnormalities. This raises a clinical question of whether DM really does not affect lower urinary tract functions in patients with well-controlled DM. This study aimed to determine the urodynamic findings in patients with well-controlled DM and no apparent diabetic neuropathy.

Of treatment-naive men who visited our hospital with the chief complaint of LUTS and underwent urodynamic studies (UDS), men who had DM, with no apparent neurological complications and was well-controlled (Hemoglobin A1c < 7.0%) by treatment were included as the DM group in the study. Notably, patients matched using a propensity score matching (PSM) analysis to the DM group for backgrounds that might affect lower urinary tract functions, including age, prostate volume, and the presence or absence of hypertension and hyperlipidemia, were set as the non-DM group, and the UDS parameters were compared between the two groups.

An analysis of the UDS records of 987 male patients showed that 139 men had well-controlled DM and no apparent neurological complications (DM group). From the remaining men, 139 patients were selected as the non-DM group using a PSM analysis. As shown in the Table, there was no difference in serum creatinine level, serum prostate specific antigen level, and the subjective symptoms, including international prostate symptom score and overactive bladder symptom score, between the two groups. Upon comparison of the UDS parameters on lower urinary tract functions, there was no significant difference in the bladder outlet obstruction index and the incidence of detrusor overactivity, while maximum flow rate, the bladder contractility index (BCI), and bladder voiding efficiency were significantly lower in the DM group. Especially, the proportion of patients with BCI < 100 was significantly higher in the DU group (63% vs. 44% in the non-DM group) (P < 0.001).

Diabetic neuropathy is known to worsen by prolonged hyperglycemic condition. However, the decrease of detrusor contractions was observed in even patients with well-controlled DM and it was thought that the damage of efferent nerve could occur in the bladder, even with mild DM.

Male LUTS patients with DM are more likely to develop DM-related bladder dysfunction (decrease of bladder contractility), even if their DM was well-controlled and there were no obvious neurological complications. It should be noted that even well-controlled DM can cause potential bladder dysfunction in real-world practice.