INS and obesity due to melanocortin 4 receptor deficiency: Besides, secondary hypogonadism is predominately associated with overweight and obesity, which makes it likely that increased aromatization of T to E2 in adipocytes, increased insulin resistance, and proinflammatory cytokine production (tumor necrosis factor a and interleukin 6) from adipose tissues may have a negative impact on the vitamin D endocrine axis (28).