Are insulin resistance and non-alcoholic fatty liver disease associated with Peyronie's disease? A pilot study

Risk factors for Peyronie's disease (PD) are serum lipid abnormalities, hypertension and type 2 diabetes mellitus (T2DM). Oxidative stress and inflammation are key-players in the pathogenesis of arterial diseases, leading to insulin resistance (IR), which is a major determinant of non-alcoholic fatty liver disease (NAFLD). We studied the potential relationship between PD, IR, and NAFLD. Forty-nine male patients were enrolled, fulfilling the well-accepted diagnostic criteria of stable PD. Fifty male individuals without PD, well-matched for age and BMI, were selected as the control group. Comorbidities (T2DM and hypertension), as well as the lipid profile and the glucometabolic asset, were evaluated. The triglycerides/HDL ratio (TG/HDL-C ratio) with a cut-off of ≥3 and the triglycerides-glucose index (TyG) with an optimal cut-point of 8.5 were used for diagnosis of IR and NAFLD, respectively. NAFLD diagnosis was confirmed by the presence of bright liver at ultrasonography. Hypertension was found more frequently in PD patients than in no-PD subjects (P=0.017), independently of age (P=0.99). Both IR and NAFLD were significantly associated with the presence of PD in our population of men (P=0.043 and 0.0001, respectively), no matter how old (P=0.11 and 0.74, respectively). At logistic regression, NAFLD was the only predictor of the PD presence (p=0.021). The AUROC of TyG to predict PD was 0.7437 (sensitivity 67.35% and specificity 80%) with a percentage of correctly classified patients of 73.74%. Oxidative stress markers were significantly associated with NAFLD. Testosterone level was significantly low in the subjects with NAFLD in cross-sectional analyses. Both factors, i.e., oxidative stress and hypogonadism, are central to PD pathogenesis. In conclusion, NAFLD and IR are strongly associated with PD. The pathogenic link between these conditions and the underlying mechanisms are only hypothetical and thoroughly summarized in the discussion.