First diagnosed before pregnancy and is divided into two groups. T1DM results from autoimmune destruction of pancreatic β cells and is characterized by early onset with necessary insulin therapy. The more common T2DM is associated with peripheral insulin resistance, insulin deficiency, and obesity and is characterized by late onset. Risks are reportedly more common in pregestational DM than in gestational DM. This evidence concerns the gene INS and type 2 diabetes mellitus.