Insulin Requirements in Type 1 Diabetic Pregnancy: Do twin pregnant women require twice as much insulin as singleton pregnant women?

OBJECTIVE: To evaluate the insulin requirements in women with type 1 diabetes during twin pregnancy compared with singleton pregnancy. RESEARCH DESIGN AND METHODS: At 8, 14, 21, 27, and 33 gestational weeks, insulin requirements and HbA(1c) were compared between 15 twin pregnant women from 2000 to 2011 and 108 singleton pregnant women from 2004 to 2006. RESULTS: In twin pregnancies, the weekly increase in daily insulin dose between 14 and 27 weeks was higher than in singleton pregnancies (median 3.0 international units [IU] [range 0.9–4.9] versus 1.5 IU [−1.5 to 5.9]; P = 0.008) and remained stable from 27 to 33 weeks. The increment in total insulin requirement from before pregnancy until 33 weeks tended to be higher in twin pregnancies (103% [36–257%] versus 71% [−20 to 276%]; P = 0.07). Throughout pregnancy, HbA(1c) was similar in twin and singleton pregnancies. CONCLUSIONS: In twin pregnancies, the weekly increase in insulin dose between 14 and 27 weeks was doubled compared with singleton pregnancies.