July 5, 2006
Gestational Diabetes, Insulin
Question from Atlanta, Georgia, USA:
I am in my third pregnancy with gestational diabetes. When I am not pregnant, I do have some insulin resistance. I was diagnosed with gestational diabetes at 18 weeks pregnant (barely passed my 12 week screening) and started insulin injections in my 20th week.
Last week, at 35 weeks pregnant, I was taking 22 units of NPH in the morning and 18 units of NPH at bedtime. I was also using a 2:1 carbohydrate to Humalog ratio at breakfast, 10:1 at lunch and 15:1 at dinner. I was taking nearly 100 units of insulin a day.
In the past week, I have gone from needing a lot of insulin just to keep my blood sugar under 150 mg/dl [8.3 mmol/L] postprandial and under 100 mg/dl [5.6 mmol/L] fasting, to having to stop taking ALL INSULIN. I kept having hypoglycemic reactions and I was constantly having to eat to keep my sugars up above 70 mg/dl [3.9 mmol/L]. Even now, with no insulin, I have gone to the low 60s mg/dl [3.3 to 3.5 mmol/L] with snacks and my fastings are between 60 and 70 mg/dl [3.3 and 3.9 mmol/L[ in the mornings. While I was on insulin, they were usually 90 to 115 mg/dl [5.0 to 6.4 mmol/L].
The doctors seem concerned that my placenta is starting to deteriorate but, so far, have decided that as long as the baby is active and the tests are reactive, I can and should remain pregnant. I have had every other day non-stress tests and a biophysical profile this week. All the tests were good.
I am very worried that if we continue to wait, something bad will happen. I was looking for some advice on this type of situation. Is it common? Does it usually have a good outcome?
The sudden decrease in insulin requirement is unusual, but I have seen this in previous patients. I do not have a good explanation. However, the concern would be that the placenta is producing less of the hormones that cause insulin resistance implying that the placenta is losing some function. As long as the fetal testing remains reassuring, then there is not an immediate need for delivery. I would recommend an amniocentesis for lung maturity at 36 to 37 weeks. If the baby’s lungs are mature, then early delivery is worth considering.