MTNR1B and type 2 diabetes mellitus: First, several genome‐wide associations studies (GWAS) have reported, that the frequent rs10830963 single‐nucleotide polymorphism, located in the melatonin receptor 2 gene (MTNR1B), which may be a gain‐of‐function variant, is strongly associated with elevated fasting glucose and risk of type 2 diabetes.4, 5, 6, 7, 8