Glycemic and metabolic features in gestational diabetes: singleton versus twin pregnancies

A number of data on gestational diabetes mellitus (GDM) in singleton pregnancy is available, however, little is known about the glycemic characteristics of twin pregnancy with GDM. The aim of this study was to compare the severity of dysglycemia between twin and singleton pregnancies with GDM (T-GDM and S-GDM). We retrospectively analyzed pregnancies with GDM defined by the Japan Diabetes Society criteria (T-GDM, n = 20; S-GDM, n = 451) in our hospital. During the study period, women with GDM underwent self-monitoring of blood glucose measurements as well as dietary management. Insulin treatment was initiated when dietary treatment did not achieve the glycemic goal. The glycemic and metabolic characteristics were compared between T-GDM and S-GDM, as follows: gestational week at the diagnosis of GDM, 75 g oral glucose tolerance test (OGTT) results, HbA1c, insulin secretion (i.e. insulinogenic index [IGI] and Insulin Secretion-Sensitivity Index-2 [ISSI-2]), and insulin requirement before delivery. The rate of one abnormal OGTT value in T-GDM was similar to that in S-GDM (60% vs. 71%). There were no significant differences in gestational week and levels of HbA1c at diagnosis, levels of IGI and ISSI-2 between T-GDM and S-GDM (median, 20 weeks vs. 17 weeks, 5.0% vs. 5.2%, 0.58 vs. 0.71, 1.7 vs. 1.8, respectively). The rate of insulin treatment and a median dosage of insulin needed before delivery was comparable between the two groups (T-GDM vs. S-GDM: 45% vs. 32% and 14 vs. 13 unit/day). Our data suggested that the severity of dysglycemia in T-GDM was similar to that in S-GDM during pregnancy.