INS and Hypergonadotropic hypogonadism: This narrative mini-review analyzes previous studies applying ultra-high-performance liquid chromatography–high-resolution mass spectrometry (HRMS)-based metabolomics to highlight different metabolic pathways involved in male hypogonadism and testosterone replacement therapy, both in the case of insulin-sensitive patients with primary hypogonadism and in the case of insulin-resistant patients with functional hypogonadism.