MTNR1B and type 2 diabetes mellitus: Variants in T2D susceptibility genes involved in insulin secretion (such as TCF7L2 [coding for transcription factor 7-like 2] and MTNR1B [coding for melatonin receptor 1B]) and in insulin resistance (such as PPARG [peroxisome proliferator activated receptor γ]) have been associated with GDM, suggesting a similar genetic architecture between these two metabolic diseases, although it is believed that some genes are unique to GDM [17].