In general, if a woman has pregestational diabetes and is taking an oral medication for blood sugar control, it will be necessary to discontinue the oral medication and initiate insulin (injections) therapy during pregnancy.
The safety of taking oral diabetes medications, particularly in the early part of pregnancy when the fetus is still forming (organogenesis), has not yet been determined. Early generation sulfonylurea drugs crossed the placenta and had the potential to stimulate the fetal pancreas leading to high levels of insulin in the fetus. This caused concern over the potential harm to the fetus; however, it is difficult to distinguish the effects of the treatment from those of poorly controlled diabetes and high blood sugars.
Glyburide, a second generation sulfonylurea, has been studied in pregnant women with gestational diabetes (GDM). It was compared to insulin treatment in a randomized controlled trial and glucose control was similar. In addition, the glyburide and insulin groups had similar pregnancy outcomes including cesarean delivery rates, preeclampsia, macrosomia (> 4 Kg baby) and neonatal low blood sugars.
Cord blood studies showed no detectable glyburide in the infants (Langer et al. New Eng J Med 2000;343:1134-1138). The results from this study have not been confirmed and further investigations are needed before oral medications can be used safely during pregnancy.
Most of the time, a combination of fast and long-acting insulin are prescribed during pregnancy. Fast-acting insulin is given before meals while long-acting insulin provides a small amount in the bloodstream at all times. The specific insulin type will be individualized according to the patient's needs but the most common regimen combines a fast-acting (clear) insulin such as Humulin R (Regular) or Humalog® (Lispro) with an intermediate acting insulin, NPH (cloudy).
Onset Of Action
Works Best (Hours)
Effect Ends (Hours after dose)
Low Blood Sugar Likely
|Humalog ® /Lispro- Very Short Acting*||10 min||1.5||3||4-6|
|Novolog ®||10 min||1||5||3-5|
|Short-Acting** Regular||20 min||3-4||8||6-8|
|Long-Acting, Ultralente UL||4hr||10-24||36||12-28|
* Humalog® and NovoLog® should be given 0-15 minutes before meal.
** Regular should be given 30 minutes before meal.
An insulin infusion pump can deliver insulin in very tiny amounts. It is about the size of a pager and is attached to the body by a long thin tube. Pumps are relatively expensive but some insurance companies are now covering their cost.
Insulin pumps are rapidly becoming more available to women with pregestational diabetes. Only fast-acting insulin is used in the pumps and at present only Regular and Novolog® have been FDA approved for use in pumps, however, some health care providers have used Humalog® with good results. Use of a pump enables more precise insulin dosing.
The insulin pump usually combines different types of insulin and insures controlled basal levels of insulin by administration of exact dosages in a continuous fashion. It also provides the boluses of insulin necessary just before a meal or snack.
Insulin pumps can be particularly helpful in the management of women with diabetes during the first trimester when pregnancy is often complicated by nausea and vomiting (unpredictable food intake). Although the experience with pump therapy during pregnancy is still limited, it offers a theoretical benefit and should be seriously considered in select patients.
Patients with the following characteristics me be candidates for the pump:
- If there is a tendency to have hypoglycemic episodes or wide glucose level fluctuations despite compliance with diet and insulin dosing recommendations.
- Hypoglycemia symptoms do not occur until the blood sugars are too low for appropriate intervention.
- Problems with "hyperemesis gravidarum" (nausea and vomiting of pregnancy) create high risk when taking a large amount of insulin and being unable to keep food down. A pump makes it much easier to adjust the insulin infusion immediately.
- More flexibility in the insulin regimen may be needed due to irregular work shifts or travel.
- Patient dissatisfaction with daily injections. Most insulin pump infusion sets only need to be replaced every 3 days.
Potential Complications with Insulin Pumps
Pump therapy is as safe as multi-dose insulin when recommended procedures are followed. Potential complications peculiar to pump therapy include undetected interruptions in insulin delivery (which may result in ketotic episodes) as well as infections or inflammation at the needle site. These complications are extremely rare. In general, the benefits of pump therapy far outweigh the potential risks in most patients.