LEP and obesity due to melanocortin 4 receptor deficiency: Although a state of hyperleptinaemia is considered physiological, multiple studies reported significantly higher leptin levels in women with GDM.53–55 This could be the result of a combination of factors, including polymorphisms in the LEP rs2617270 allele of the gene that codes for this hormone, obesity prior to conception and excessive weight increase during pregnancy.52,55–57 These conditions are associated with IR and states of compensatory hyperinsulinaemia.