Main idea: Pre-gestational BMI and weight gain may play a role in determining CHO/IR during pregnancy in women with type 1 diabetes under pump treatment.
The primary aim of this study was to assess insulin requirements and carbohydrate to insulin ratio (CHO/IR) in normal weight, overweight, and obese pregnant women with type 1 diabetes across the early, middle, and late pregnancy.
Results: We studied 45 normal weight, 31 overweight, and 10 obese women. Insulin requirements increased throughout pregnancy in normal and overweight women, while it remained unchanged in obese women. Insulin requirements were different between groups when expressed as an absolute value, but not when adjusted for body weight. Breakfast CHO/IR decreased progressively throughout pregnancy in the normal-weight women, from 13.3 (9.8-6.7) at the first stage of pregnancy to 6.2 (3.8-8.6) at the end stage, and in the overweight women from 8.5 (7.1-12.6) to 5.2 (4.0-8.1), while in the obese women it remained stable, moving from 6.0 (5.0-7.9) to 5.1 (4.1-7.4). Likewise, lunch and dinner CHO/IR decreased in the normal weight and overweight women (p < 0.03) in contrast to the obese women. The obese women gained less weight than the others, especially in early pregnancy when they even lost a median of 1.25 (-1 -1.1) kg. In early pregnancy, we found a correlation between pre-gestational BMI and insulin requirements (IU/day) or CHO/IR at each meal. In late pregnancy, a relationship between pre-gestational BMI and CHO/IR change was found, as well as between weight gain and CHO/IR change. The significance was lost when both variables were included in the multiple regression analysis. There was no difference in pregnancy outcomes except for a higher preterm delivery rate in obese women.