Gestational diabetes mellitus in twin pregnancies versus singleton pregnancies-A retrospective case-control study

To compare markers of glycaemic regulation in twin and singleton pregnancies in women with gestational diabetes mellitus (GDM).

A retrospective case-control study was performed. 53 twin and 212 matched singleton pregnant women with gestational diabetes were included. Data were obtained from patient files. Twin and singleton pregnant women were compared regarding clinical characteristics and parameters related to glucose metabolism.

Compared to singleton pregnant women, twin pregnant women were diagnosed with GDM earlier in pregnancy (gestational age (GA) (weeks + days) 24 + 5 ± 5 + 2 vs. GA 27 + 2 ± 5 + 2; p = 0.002). The proportion of women treated with insulin was similar (24.1% vs. 24.5%, p = 1.0), but in twin pregnancies, insulin treatment was commenced earlier (GA 25 + 2 ± 4 + 6 vs. GA 30 + 1 ± 5 + 0; p = 0.003). At diagnosis, the HbA1c value was significantly lower in twin pregnant women (34 (5.3) ± 4.8 (2.6) vs. 35.9 (5.4) ± 5.4 (2.6), p = 0.03), but mean HbA1c values were similar in 2nd (33.9 (5.3) ± 4.6 (2.6) vs. 35.7 (5.4) ± 5.3 (2.6), p = 0.16) and 3rd trimester (35.1 (5.5) ± 4.2 (2.5) vs. 36.0 (5.4) ± 5.1 (2.6), p = 0.25).

We have characterized the effect of twin pregnancy on parameters of glucose metabolism and glycaemic control in GDM in one of the largest studies of twin pregnant women with GDM to date. We conclude that twin pregnant women may have the GDM diagnosis earlier, but diurnal insulin requirements and HbA1c levels are comparable with singleton pregnant women.