August 22, 2001
Family Planning, Insulin Analogs
Question from Torrance, California, USA:
I’m a 29 year old female who has have type 1.5 diabetes, diagnosed two years ago at the very beginning of a pregnancy, and I’ve been taking 75/25 mixed insulin along with Glucophage [metformin] and Actos [pioglitazone]. I would like to get pregnant again soon, so I went to my endocrinologist who took me off the pills and replaced them with Lantus in addition to the mixed insulin.
My concern is the effects of the Lantus on the fetus. In the fine print in the Lantus pamphlet, I read that there were five brain deformed fetuses in two litters of rabbits tested. It also read that only pregnant women who need Lantus should take it. I don’t want to be over paranoid, but I am worried. I never read the fine print during my first pregnancy when I took N and R so I don’t have anything to compare it to. Should I be concerned? What has been tested and found to be the safest insulin to take while pregnant and then nursing after that? Why would my doctor prescribe an insulin that wasn’t completely safe?
Human N and R [Humulin and Novolin brands] have been used for many years without apparent effects on fetal development. There is much less experience with the newer insulins such as Humalog and Lantus (insulin glargine), although these are being used without apparent ill effect. The critical time of development is the first eight to ten weeks after conception. If you want to minimize your risks as much as possible, then you should use the more traditional insulins during the first part of the pregnancy and switch over to other types after 10 weeks.