HNF1A and type 2 diabetes mellitus: Previous works have also assessed the role of variation in the HNF1A gene (responsible for MODY3) in susceptibility to both T2D and GD, suggesting that HNF1A may participate in pathways involved in abnormal blood glucose levels and that HNF1A variants may lack sufficient penetrance to cause diabetes but may still increase the susceptibility to T2D and GD [4–10].