Does Insulin Resistance Predict Lower Urinary Tract Symptoms? Results From the Reduction by Dutasteride of Prostate...

We previously found that higher insulin resistance (IR) was associated with larger prostate size and greater risk of benign prostatic hyperplasia (BPH). Since BPH is the most common cause of lower urinary tract symptoms (LUTS), we investigated whether IR is also linked to incidence and progression of LUTS in the REDUCE study, a 4-year randomized trial of dutasteride vs. placebo for prostate cancer prevention.

Participants were required to complete the International Prostate Symptom Score (IPSS) questionnaire at recruitment and every subsequent 6 months. Fasting insulin and glucose levels were measured at study baseline, and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) was calculated based on these values. Multivariable Cox regression was used to assess associations between HOMA-IR and (1) LUTS incidence among asymptomatic patients (baseline IPSS < 8); or (2) LUTS progression among symptomatic patients (baseline IPSS ≥ 8) respectively.

As previously reported within this cohort, at baseline, higher HOMA-IR quartiles were correlated with larger prostate volumes among both asymptomatic (N = 2745; p < 0.001) and symptomatic patients (N = 1942; p = 0.007). However, among asymptomatic patients, HOMA-IR whether analyzed as a continuous (p = 0.74) or categorized variable (all p ≥ 0.60) was not associated with LUTS incidence in multivariable analysis. Similarly, in symptomatic participants, no associations were found between HOMA-IR and LUTS progression in multivariable analyses, whether HOMA-IR was assessed as a categorical (all p ≥ 0.46) or continuous variable (p = 0.83).

Although IR was linked to larger prostate volumes, it was not an independent risk factor of LUTS development or progression despite the known associations between BPH and LUTS.