Pregnancy is a diabetogenic state due to impaired insulin sensitivity. Pregnancy worsens diabetes, while poorly controlled diabetes results in fetal, neonatal and maternal complications. Fetal hyperinsulinemia occurring as a result of maternal hyperglycemia is responsible for all the perinatal complications. Diabetes mellitus (DM) is a common medical disorder encountered in pregnancy. Obesity and advanced maternal age are other risk factors for diabetes. Perinatal mortality and morbidity are high in untreated diabetic pregnancies. However, this has decreased considerably with screening, antepartum fetal surveillance and insulin therapy. Elevated placental hormones such as estrogens, progesterone, prolactin and human placental lactogen (hPL) act as insulin antagonists. They oppose the action of insulin, making it less effective. Glucose challenge test (GCT) is commonly used in screening for gestational diabetes. Oral glucose tolerance test (OGTT) is performed for the diagnosis of gestational diabetes. Fetal anomalies and abortions are seen in pregestational diabetes when euglycemia is not maintained during periconceptional period. Neural tube defects, cardiac and renal anomalies occur with increased frequency in diabetic pregnancies. Caudal regression syndrome, a rare anomaly is characteristic of diabetic pregnancy. An infant of a diabetic mother (IDM) has a plethoric appearance due to polycythemia. Low electrolytes are due to renal loss and decreased parathyroid hormone secretion in these babies. Prematurity and birth asphyxia further aggravate the neonatal complications in IDM. Pregestational diabetic requires evaluation and surveillance for nephropathy, retinopathy and ketosis during pregnancy. There are high chances of a cesarean section in a diabetic mother due to pregnancy complications or macrosomia. It is important to maintain euglycemia during labor to minimize the risk of neonatal hypoglycemia. Continuous fetal heart rate monitoring is ideal. Partogram should be maintained. Epidural analgesia is helpful. Evaluation of thyroid function is also recommended in type 1 diabetes as hypothyroidism is frequently encountered in these women.