Objective:
Introduction of insulin therapy in gestational diabetes mellitus (GDM) is determined by whether or not target blood glucose levels are achieved by using self-monitoring of blood glucose (SMBG) under nutritional therapy. However, in women who achieved the target glucose under nutritional therapy, there are no certain consensus on how long SMBG should be maintained during pregnancy. In this study, we examined the timing of the introduction of insulin therapy in women with GDM diagnosed during the second trimester and estimated the gestational age when SMBG could be discontinued.
Methods:
In a single-center, retrospective study, singleton pregnancies diagnosed with GDM at 24-32 weeks' gestation were included. We examined the week of gestation when insulin therapy was initiated by using SMBG assessment under nutritional therapy after GDM diagnosis. Insulin therapy was indicated if the SMBG value did not reach approximately ≥80% of the fasting and postprandial target glucose values, respectively.
Results:
Among 311 GDM patients included in the study, 179 (58%) and 132 (42%) were treated with diet alone throughout pregnancy (diet group) and with insulin therapy (insulin group), respectively. The insulin therapy was begun at 29±2 (range 24-36) weeks’ gestation, the time from diagnosis to introduction of insulin therapy was 1.8±1.6 (0-10) weeks, and the maximum insulin dose was 32±23 (4-148) units/day. The introduction after 33 and 34 weeks’ gestation was observed in 13 patients (10% of the insulin group) and only one patient (0.8%), respectively. In the diet group, 30% of patients continued SMBG until delivery, and the gestational age at discontinuation of SMBG was 31±3 (25-39) weeks’ gestation.
Conclusion:
In most of the patients with GDM diagnosed during the second trimester, insulin therapy was initiated by 33 weeks’ gestation. It was suggested that SMBG for the decision of insulin induction may be discontinued after 34 weeks of gestation.