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From Kansas, USA:

I have had Type 1 diabetes for 10 years and am 30 years old. I have a 2 year old daughter and the pregnancy went great. About 6 months ago, my doctor switched me to the new insulin (Humalog). We are contemplating pregnancy again and I was wondering if I should stay on this new insulin or not when pregnant. My doctor (endocrinologist) said it was up to me. I haven't discussed it with my OB-GYN yet. Then I read the Letter to the Editor of The New England Journal of Medicine. Now I'm worried about staying on Humalog for my next pregnancy.


This Letter to the Editor raises many unanswered questions about the safety of lispro insulin during pregnancy. Since controlled trials are only just beginning, there is no scientific evidence in humans to quote -- only anecdotes and animal data.

First of all, there is no way at this time to even guess whether this report of congenital malformations in babies born to two woman using lispro during pregnancy is related to the use of lispro, some other cause, or just coincidence. One possible cause for such an occurrence in one clinic would be a virus that was circulating at the time the two woman were in the first trimester. Many viruses can be asymptomatic yet can cause congenital malformations unrelated to diabetes. It is also important to remember that congenital malformations are more common in women with diabetes, though the risk is significantly minimized with strict control both before and during the pregnancy. (A normal HgbA1C doesn't mean there weren't some highs and lows which could have affected fetal development. HgbA1C measures average control during a 2-3 month period. Averages of highs and lows can come out to a normal overall average.)

It is also important to remember that woman without diabetes or any other medical problem can have babies with congenital malformations and this occurrence may be pure chance unrelated to diabetes.

We must remember that lispro has not yet received FDA approval for use in pregnancy. Only testing of Humalog in large numbers of pregnant woman compared to use of Regular can establish whether the use of Humalog increases, decreases, or has no effect on the risk of congenital malformations.

Finally, in my opinion, I think this report underscores the importance of pressuring the FDA to include safety testing in both pregnant woman and young children of drugs like lispro that have a low theoretical risk of problems and high theoretical chance of advantages in pregnant woman and young children.

If you are planning a pregnancy in the near future and have recently switched to lispro, you should discuss with your own physician which insulin you should use in pregnancy. If you do not plan to use lispro in pregnancy and are on it now, you should discuss with your physician possibly switching back to Regular and obtaining the best control possible on Regular before conceiving.

If you are already pregnant and on lispro, you should not stop it without first discussing this with your doctor! You want to make sure to obtain the best possible control during pregnancy.

We all await the results of rigorous, large scale studies to answer this very important question.


Additional Comments from Dr. Jones:

I read the NEJM letter. The report is concerning, but as stated in the reply from Lilly, this cannot be absolutely atributed to the use of Lispro. Obviously no one wants to relive the days of thalidomide, but at the same time a very useful drug should not be dumped because of some case reports.

I agree with the response by Dr. Lebinger. Also, if the patient is very concerned about the risks to the fetus, then she should switch to regular insulin during the preconceptual period and first 9 weeks of pregnancy to eliminate any potential adverse effects during embryogenesis.


Original posting 7 Oct 97
Additional comments added 13 Oct 97


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Last Updated: Tuesday April 06, 2010 15:08:54
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