The chapter studies various case studies with finding of diabetes during pregnancy. The case depicts presenting complaints, history of presenting complaints, history of present pregnancy, menstrual history, obstetrical history, past history, personal history, dietary history, family and socioeconomic history, general examination, abdominal examination, per speculum examination, and diagnosis of the problem of the patient. The cases are related to diagnosis of type 2 diabetes mellitus and gestational diabetes mellitus during antenatal period. It covers pre-conceptional advice, maternal complications associated with diabetes during pregnancy, signs and symptoms of hypoglycemia, Somogyi and dawn phenomenon, effect of pregnancy on carbohydrate metabolism, shoulder dystocia, difference between venous plasma sugar and venous blood sugar levels, and many more topics.