Male lower urinary tract symptoms (LUTS) are characterized by bladder and/or prostate dysfunction and include storage (eg, urgency, frequency, nocturia), voiding (eg, hesitancy, poor flow), and post-micturition (eg, post-void dribble or incomplete emptying) symptoms.1 LUTS in adult men is highly prevalent, with some estimates suggesting that up to 90% of men over age 50 suffer from some form of LUTS.2 Yet, despite its commonness, symptoms of LUTS are often underdiagnosed and undertreated.3
An important component in improving diagnosis and treatment of LUTS involves becoming aware of its risk factors. Several studies have found a strong association between type 2 diabetes and LUTS.4 However, these studies did not use a consistent definition of LUTS,5 and other studies did not find this association.6 Identifying a potential association between these two conditions could suggest that clinicians should exercise greater vigilance in screening for LUTS in men with diabetes, and greater rigor in treating diabetes symptoms.
To investigate the role of diabetes as a potential risk factor for LUTS, Van Den Eeden and colleagues5 utilized questionnaire and clinical data from two large multiethnic cohorts: the California Men’s Health Study (CMHS)7 and the Research Program in Genes, Environment, and Health (RPGEH), a previous study of LUTS in a cohort of 140,139 men.5 All participants completed the American Urological Association Symptoms Index (AUASI),8 as well as a questionnaire that included information such as race/ethnicity, marital status, weight, diabetes status, comorbidity, smoking, alcohol use, and physical activity. The researchers identified 9,579 (12.2%) of 78,273 men in the CMHS cohort and 15,007 (14.1%) of 106,373 men in the RPGEH cohort who had current or past diabetes.
The researchers found a “clear association” between type 2 diabetes and LUTS (OR=1.32, 95% CI 1.26, 1.38). Men with type 2 diabetes reported higher AUASI scores in each age group in both cohorts, and men with type 2 diabetes were 32% more likely to report LUTS, compared to men without type 2 diabetes. The association was stronger among diabetic men who were receiving active pharmaceutical treatment (eg, oral antihyperglycemia agents or insulin). Longer duration of type 2 diabetes was also associated with increased odds of LUTS, although even men with shorter duration of diabetes were more likely to suffer from LUTS than those without diabetes. No association was found between type 2 diabetes and new-onset LUTS.
In reflecting on their study findings, the authors raise the question of the mechanism of action at play in the association between type 2 diabetes and LUTS. They cite several studies9, 10,11,12 pointing to an association between diabetes and voiding function, but note that these studies have not identified the underlying mechanism—ie, dysfunction due to increased obstruction secondary to benign prostatic hyperplasia (BPH) or bladder dysfunction secondary to microvasculature and neuropathic effect related to diabetes.
The authors suggest that the impact of diabetes on voiding symptoms is unlikely to be related obstruction, as a study conducted by Sarma et al found no association between diabetes and prostate volume.13 Rather, diabetes may adversely impact voiding through its effect on the bladder, which is manifested in later stages as diabetic cystopathy. The impact of diabetes on the bladder, they suggest, may be mediated through vascular and neuropathic mechanisms.
The practical implications of the strong association between type 2 diabetes and LUTS are summarized in an article by Brown and colleagues. “Intensive glycemic control delays the onset and progression of microvascular complications of … type 2 diabetes. … If microvascular complications also damage the vascular and neurologic innervation of the urethral sphincter, bladder, and corpora cavernosa, then intensive glycemic control may prevent or improve severity of urologic complications.”14