With my first baby, Jenn warned me to turn off my pump immediately after birth or else my blood sugar would get terribly low, based on her experience. I followed that advice, but just found that my blood sugar was up in the 200s by morning. I actually don't remember what happened after that, because I wasn't anticipating writing a blog post about it. I also didn't think I'd need to store such information in my brain, which was already overloaded with information such as "how to change a diaper without being peed on," because I was planning to tell my husband we couldn't have any more children.
(That was just three years ago, and as you can see, I would not recommend making decisions about future childbearing in the first 3 weeks after the baby is born. Just don't. Unless you plan to resume sexual activity during that time. Which I also wouldn't recommend.)
With the last two babies, I lowered my basal rates and bolus ratios immediately to avoid the hassle of dealing with lows, but I found that I didn't start to get lows until my milk came in. With Braveheart, I woke up in a sweaty low at 5:00a and drank all the juice I could get my hands on. I don't remember what the number was (somewhere in the 30s), but it was about 36 hours after his birth. With the Statesman, it was also about 36 hours after birth. I noticed one feeding during which he seemed to be gulping quite a bit more than usual, which I attributed to the milk beginning to come in, and about an hour later my blood sugar was 34. Just this morning, at my 6-week check-up, my OB told me about finding an unconscious Type I diabetic woman in her postpartum recovery room during morning rounds with a blood sugar of 12. 12! Oh, my! Holly, over at Arnold & Me, found she regularly ran low while breastfeeding early on.
So here are some observations I've made about managing insulin rates postpartum.
It's OK to run a little high while you're in the hospital and getting used to your baby. Much better than being low when you're trying to handle a newborn. A few days just won't kill you. (Blood sugar of 12. 12! Oh, my!) Maybe try something like 1/2 your normal basal rates, and take 1-2 carbs per unit off your bolus ratio. That's what I did this time around, and it worked out OK.
Err on the side of underestimating carbs while you're in the hospital. And don't even bother counting carbs for vegetables or fruit or ketchup while you're in the hospital. Keep your Gatorade or juice of choice close by.
Keep checking your blood sugar as frequently as you did during pregnancy, at least for the first week. You may not be able to tell if you're about to pass out because you were awake for four out of eight sleeping hours last night or because your blood sugar is low. Extra information will also help you figure out how to adjust your insulin rates.
You might spend a lot of the first month tweaking your basal rates and bolus ratios. I find I am adjusting my basal rates and bolus ratios almost every day, or every other day. Mostly down. I'm actually below pre-pregnancy bolus ratios by this point (6 weeks), and still tweaking down. I only wait two days before making a move to correct a trend (say, lows after lunch two days in a row). That's how I do it during pregnancy, too.
You may notice a correlation between weight loss of 5 pounds or more and a decreased need for insulin, particularly bolus ratios. After Braveheart was born, I was still adjusting my insulin rates downwards until I bottomed out on my weight loss around 8 months out.
You won't need to eat as much to raise the same low blood sugar you had during pregnancy. If it took 20 grams of carb to raise a blood sugar of 60 during pregnancy, it will only take 10 postpartum. Or something like that. I don't know what your numbers are, but I found it took a whole bottle of Gatorade during pregnancy, and now it only takes a half.
There are lows during the early weeks of breastfeeding, but it does get better. Now that I'm six weeks out, I love not chasing the lows like I did during pregnancy. If my 2-hour postprandial is 105, I won't be protecting a bottle of Gatorade from two toddlers until my next meal, because, happily, I will be drinking water instead! And that means I spend less time plotting my next encounter with food and more time with my babies. Awesome.
UPDATE: I forgot that I wrote about this when Braveheart was three months old. Oh well. Fortunately, it's pretty similar stuff.