Association Between Overactive Bladder and Polyneuropathy in Diabetic Patients

Physiopathology of the diabetic bladder

OBJECTIVE

To investigate the incidence of diabetic cystopathy in relation to age, gender, type of diabetes, duration of diabetic disease and clinical evidence of peripheral neuropathy and to analyze the physiopathology of the various forms of diabetic cystopathy due to sensory impairment, motor-sensory impairment, motor impairment and hyperreflexia.

MATERIALS AND METHODS

In a retrospective multicenter cohort study the medical records of a cohort of 126 diabetic patients with (128 patients) or without (48 patients) urological symptoms were analyzed. Patients were observed at the Città di Alessandria Clinic of Policlinico di Monza and/or at the outpatient clinic of Alessandria Hospital from June 2018 to June 2020. The study excluded patients with central and/or peripheral neuropathy, spina bifida (mylomeningocele or meningocele) or spina bifida occulta; with persistent urinary infections; in anticholinergic treatment for enteric dysfunctions; in medical treatment for cervical-prostatic-urethral obstruction; with vaginal and/or rectal prolapse of II, III, IV degree; with previous spinal or pelvic surgery including radical prostatectomy, Wertheim hysterectomy or colorectal surgery. All the patients were studied with computed tomography (CT) scan of the urinary tract, voiding cystourethrography (VCUG), uroflowmetry, cystomanometry with intrinsic pressure assessment and compliance evaluation, electromyography (EMG) of the anal sphincter, pressure flow analysis, urethral pressure profile and, when advised, pharmacological tests.

RESULTS

Out of 126 diabetic patients, 48 did not show any signs or symptoms of urine voiding dysfunction; 30 were men and 18 women with an average age of 62.6 years; 20 had type I diabetes and were in treatment with insulin and 28 type II diabetes treated with oral hypoglycemic medication. The remaining 78 patients (48 men and 30 women), with an average age of 64.8 years, presented urological symptoms; 31 had type I diabetes and 47 had II type diabetes.

CONCLUSIONS

Diagnosis of the various forms of diabetic cystopathy and early treatment decreases complications and consequently accesses to outpatient facilities and hospital admissions, resulting in an improved quality of life.

The Pharmacological Mechanism of Diabetes Mellitus-Associated Overactive Bladder and Its Treatment with Botulinum Toxin A

Diabetes mellitus (DM) is an independent risk factor for overactive bladder (OAB). The pathophysiology of DM-associated OAB is multifactorial and time-dependent. Diabetic bladder dysfunction is highly associated with diabetic complications, mainly including diabetic neuropathy and atherosclerosis. Chronic systemic inflammation and bladder urothelial inflammation may contribute to the onset of OAB. Intravesical botulinum toxin A (BoNT-A) injection has proved to be a successful treatment for idiopathic and neurogenic OAB. BoNT-A can inhibit the efferent pathways of the bladder as well as the chronic inflammation and hypersensitivity via the afferent pathways. We conducted a review of the published literature in Pubmed using a combination of two keywords, namely “botulinum toxin A” (BoNT-A) and “overactive bladder”, with or without the additional keywords “detrusor overactivity”, “diabetes mellitus”, “inflammation”, and “urodynamic study”. We also reviewed the experience of our research teams, who have published several studies of the association between DM and OAB. Since limited data support the effectiveness and safety of BoNT-A for treating patients with DM-associated OAB, a comprehensive evaluation of diabetic complications and urodynamic study is needed before treatment. In the future, it is imperative to explore the clinical characteristics and inflammatory biomarkers of diabetes as determining predictors of the treatment efficacy.

NLRP3 Promotes Diabetic Bladder Dysfunction and Changes in Symptom-Specific Bladder Innervation

The NLRP3 inflammasome senses diabetic metabolites and initiates inflammation implicated in diabetic complications and neurodegeneration. No studies have investigated NLRP3 in diabetic bladder dysfunction (DBD), despite a high clinical prevalence. In vitro, we found that numerous diabetic metabolites activate NLRP3 in primary urothelial cells. In vivo, we demonstrate NLRP3 is activated in urothelia from a genetic type 1 diabetic mouse (Akita) by week 15. We then bred an NLRP3^-/- genotype into these mice and found this blocked bladder inflammation and cystometric markers of DBD. Analysis of bladder innervation established an NLRP3-dependent decrease in overall nerve density and Aδ-fibers in the bladder wall along with an increase in C-fiber populations in the urothelia, which potentially explains the decreased sense of bladder fullness reported by patients and overactivity detected early in DBD. Together, the results demonstrate the role of NLRP3 in the genesis of DBD and suggest specific NLRP3-mediated neuronal changes can produce specific DBD symptoms.