Human analog insulin is considered the least immunogenic of all insulin preparations. Lispro (Humalog) and aspart (NovoLog) are rapid onset insulin analogs and are used as bolus (mealtime) insulin. They have a 15 minutes onset, peak in 30–90 minutes and have a duration of 3–5 hours. Lispro and aspart have been investigated in pregnant women and are classified as Category B and considered safe with minimal transport across the placenta and have been found to decrease postprandial hyperglycemia and have a lower risk of postprandial hypoglycemia compared to regular insulin preparations. Long acting (basal) insulin such as detemir (Levemir) and glargine (Lantus) have a 60 minutes onset with no peak and a duration of 20–26 hours. Detemir is considered a Category B drug and glargine is a Category C drug in pregnancy that has been found unlikely to cross the placenta. The most common oral antihyperglycemic medications used in pregnancy include the insulin sensitizers and insulin secretagogues. The most common insulin sensitizer used in pregnancy is the biguanide metformin. Biguanides stimulate glucose intake in the liver and periphery and suppress hepatic glucose output. Metformin (Glucophage) is Pregnancy Class B and has been found to cross the placenta, with cord levels twice maternal levels. When metformin and insulin were examined by Rowan et al in a randomized clinical trial (MiG Trial), metformin alone or with supplemental insulin was not associated with increased perinatal complications. Although women randomized to metformin seemed to prefer this mode of medication delivery, unfortunately, approximately 50% still required insulin to meet their glycemic goals. Further well-designed randomized controlled trials are needed to fully examine the risk to the fetus. Patients who decide to take metformin should be counseled on the unknown risks to the fetus.