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Mary Loeken Part 2, What Types Of Diabetes Cause Birth Defects

In part 2 of this Exclusive Interview, Dr. Mary Loeken talks with Diabetes in Control Publisher Steve Freed during the ADA meeting in San Diego, CA about the potential types of birth defects caused by gestational diabetes.

Mary Loeken, PhD is an Associate Professor of Medicine at Harvard Medical School and an Investigator at Joslin Diabetes Center.

Transcript of this video segment:

Steve: I know that you’re presenting here and I think the title is, Worming Our Way Into Understanding the Basic Science of Effects of Metformin and Glyburide on the Fetus and How That Affects Neural Issues. Your research focuses on birth defects caused by diabetic pregnancy.  What kinds of diabetes can cause birth defects, and does gestational diabetes also cause birth defects?

Dr. Loeken:  That is really a good question and it’s something that when I make presentations about I try to clarify at the beginning that we’re working with pre-gestational diabetes. Gestational diabetes, if it is truly gestational diabetes, has its onset about halfway through pregnancy.  By that time the organ systems of the fetus have formed.  While there still can be adverse effects on maturation of the organs, an increased risk for metabolic disease in the offspring later in the life, and also increased risk of fetal growth leading to birth difficulties with gestational diabetes, gestational diabetes does not cause birth defects.  Either type 1 or type 2 diabetes can cause birth defects.  What we think is that it’s the increased glucose circulating in the mother’s serum very early after she has gotten pregnant that then gets transported to the embryo and disturbs the molecular processes leading to organ formation.

Steve: I’m not sure that people have a real understanding. We know what pre-diabetes is. It’s an A1c of 5.7 – 6.4%. It’s kind of simple. When it comes to pregnancy, the limitations are much lower for obvious reasons. So, what is the definition of pre-gestational diabetes?

Dr. Loeken: It means she is not yet pregnant. When we say gestational diabetes, that is a form of diabetes that is characterized by more severe insulin resistance than is normal in pregnancy.  It is only associated with the pregnancy and goes away after pregnancy. Pre-gestational diabetes means a woman is diabetic before she is pregnant, before gestation.

Steve:  So, it is someone who has diabetes who is going to get pregnant?

Dr. Loeken: By the definition, if she becomes pregnant, then she is in gestation.

 Steve:  What kind of birth defects occur in the babies of mother with diabetes?

Dr. Loeken:  Virtually any system that can develop a congenital malformation can occur with increased frequency in diabetic pregnancy.  The most common are cardiac defects. There can be valvular defects. There can be outflow tract defect. The second most common defect are neural tube defects, primarily spina bifida. Although, anencephaly, which affects the head, can also occur. There can be renal malformations, some limb deformities, and other defects that are less common in pregnancy but are significantly increased in human diabetic pregnancy.

Steve: How important is it for someone before they get pregnant and during their pregnancy to maintain normal blood sugars. It could be very difficult, especially if they already have diabetes. What are the levels? What do you try to get them to do so that they have less chance for defects?

Dr. Loeken: Really the only strategies that we have right now are planning pregnancies so that a woman has taken measures. For example, taking folic acid, which is advised for any women who are planning pregnancy and also for diabetic women to try to get her glucose into good control as usually indicated by HbA1c levels. We do know that there are a lot of metabolic changes very soon after pregnancy occurs, even before a woman may even recognize she is pregnant due to the increased metabolism by the embryo and changes to mother’s own need for insulin.  If she is in a good control of diabetes, if she knows how to control her diet, exercise, and insulin – if she’s taking insulin for type 2 diabetes, it may be insulin; it may be oral agents – but just to get her diabetes in as best control as possible to reduce the risks of malformations.

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