Insulin requirements in insulin-dependent and insulin-requiring GDM women during final month of pregnancy.

OBJECTIVE: To determine the significance of falling insulin requirements after the 36th wk of gestation in insulin-requiring pregnant women. RESEARCH DESIGN AND METHODS: Insulin requirements of women with IDDM and IRGDM were assessed from the 36th wk of pregnancy, with evaluation of maternal characteristics and fetal outcomes.
RESULTS: In 32 pregnancies of women with IDDM, there was a 5 +/- 2% decrease in insulin requirements, and in 19 pregnancies of women with IRGDM, there was a 28 +/- 10% increase. Of the 62% of women whose insulin requirements declined, the decrement was 12 +/- 2% and was associated with longer duration of diabetes (12 +/- 2 vs. 6 +/- 1 yr, P less than 0.05) but not with age, prepregnancy BMI, weight gain, or maternal or fetal complications. Only 3 pregnancies in IRGDM women were associated with a decrease in insulin requirements. Although maternal parameters were no different from those with IDDM, infants born to women with IRGDM were smaller (3531 +/- 123 vs. 3874 +/- 94 g, P less than 0.005).
CONCLUSIONS: Insulin requirements from the 36th wk of gestation commonly decreased in women with IDDM, associated with longer duration of diabetes but did not carry any adverse prognostic indication for the infants. Women with IRGDM experienced a continual increase in insulin requirements over the final weeks of pregnancy.