Decreased insulin needs towards end of pregnancy

I am currently at almost 37 weeks and so far have had a great pregnancy with a1c’s around 6 and baby measuring around 50th percentile… My insulin needs increased significantly at about 28 weeks and have remained fairly stable since then ( I thought they would continue to increase but I guess every woman is different.). In the last week my total daily basal requirement (on pump) has dropped from 19.5 units to 15 units per day, a reduction of about 25%. I had to slightly reduce my overall rate through the whole day but most of this drop is from reducing my overnight rates. My carb to insulin ratio has also dropped from a 1u for 9g to 1u for 8g. My endocrinologist told me that if my overall insulin requirements ever drop by more than 10 or 15% I should let her and my OB/GYN know. She said that sometimes this was an indication that the placenta was aging too soon which posed a risk to the baby. I spoke with my OB today and she did not seem too worried as long as the baby is moving fine. She did suggest that rather than seeing her at our schedule appointment in two days I come in tomorrow just to make sure everything is fine.

Has anyone had the same thing happened where the insulin requirements started to drop toward the end of their pregnancy? Were you induced early as a precaution or was additional monitoring required?

Thanks! I am so close to the end and this issue has me really worried.

Katt, I believe that is pretty normal toward the end. I went to 39 weeks but in my 38th week I noticed I didn't need as much insulin that week for the same reason you described above but I was going to be induced the next week. No one seemed worried and if they weren't I wasnt. They sent me to the hospital 3 times in the last two weeks of my pregnancy! None related to the placenta and my reduced insulin rates. Are you going to the OB 2x per week or only 1x?

You are at 37 weeks so the baby is full term and could technically be born now if you needed to be induced or have a c-section. If your doctor doesn't seem too worried about it, really I wouldn't try to stress that much but, of course I know that is impossible!! Hang in there! you are almost there!!!

Same thing happened to me... it means the end is near! I was told not to get overly concerned  about placenta issues unless I all of a sudden started bottoming out. Also, lil' man was born at 37w5d completely healthy :) Excited for you!

i Katt,

I just wanted to comment on your carb to insulin ratio dropping from 1u for 9g to 1u for 8g.  So that indicates you are requiring more insulin for food (i.e. for the sake of this example, if you ate a meal with 72g of carb, using a Carb Ratio of 1:9g, that means you'd take 8 units of insulin but with a carb ratio of 1:8g, you need 9 units of insulin.)

So, if your basal rate is decreasing but you are taking more insulin for each meal, maybe these are balancing each other out so that the decrease in your total daily dose of insulin is not as great?

Thanks for the feedback! It’s good to know this is not uncommon.

Gina - I am going to the Ob once per week and also going for fetal assessment once per week. Up until 36 weeks I was going to ob one week and fetal assessments the other week so someone would see me once each week.

Emily - I got my 8 and 9 mixed up in my post! I went from 1 unit for 8g to 1 unit for 9 g of carbs. Must be pregnancy brain :slight_smile: and that must also be why I meant to write one response and accidentally posted my comment 3 times!


I started 2x per week at 32 weeks for fetal monitoring.