Relationship Between Change in Body Mass Index and Testosterone Levels in Male Patients Using GLP-1 Receptor Agonists for Weight Loss

Introduction: Originally developed for type 2 diabetes management, glucagon-like peptide 1 receptor agonists (GLP-1 RA) have gained popularity for their weight loss effects. Excess fat stores are understood to enhance aromatization in peripheral tissues, converting testosterone to estrogen, and ultimately lowering testosterone levels. This study aimed to identify the relationship between changes in body mass index (BMI) and testosterone levels in male patients using GLP-1 RA's for weight loss. Methods: A retrospective review of male patients using GLP-1 RA's was carried out from a single multicenter institutional database. Patients were grouped by age, change in BMI, and initial BMI quartiles to assess associations with average change in testosterone levels. Univariable and multivariable analysis was performed. Results: Among the 18 patients analyzed, 17 received injectable medication and 1 received oral medication. Age, change in BMI, and initial BMI were not significantly associated with changes in testosterone levels. Variability in testosterone changes across patient demographics were noted, however not statistically significant. A 15.8% variance in average change in testosterone levels was noted. Conclusions: Counter-intuitively, changes in BMI were not significantly associated with changes in testosterone levels in male patients undergoing weight loss treatment with GLP-1 RA's. While this study suggests no clear association between BMI reduction and testosterone changes with medication use, the observed variability in testosterone changes across patient demographics warrants further investigation. Additional research with a larger patient cohort and additional variables may be necessary to better elucidate potential associations between changes in BMI and testosterone levels.