Administration of antenatal corticosteroids (ACS) between 24 and 36 weeks of gestation is recommended to pregnant women at risk of preterm delivery to decrease the risk of respiratory distress syndrome, intra-ventricular hemorrhage and neonatal death. However, it may worsen glycemic profile primarily in those with gestational diabetes mellitus (GDM).

To determine the effects of ACS on maternal glycemia in Filipino women with GDM and to analyze the factors associated with insulin use or increased insulin requirement.

A retrospective study of the medical records of Filipino women with GDM who were admitted and received ACS treatment (betamethasone) between 24- and 36-weeks age of gestation (AOG) for fetal lung maturity from 2017-2019. Clinical characteristics (age, parity, completed ACS dose, AOG at ACS administration and mode of delivery) and glycemic control were retrieved and compared before and after ACS treatment. Data collection began the day or on the day before steroids were given and continued until discharge or delivery.

Included were 42 pregnant women with GDM. Of these, 28 women with GDM were treated by diet alone (Group A) while 14 women with GDM were started on insulin in addition to diet (Group B). After betamethasone therapy was initiated, only three (Group A1; n=3/28) patients had good glycemic control with diet alone and the rest were given insulin treatment (Group A2; n=25/28). In this subpopulation of Group A2, insulin requirement within 24 hours after ACS was at 0.3 units per kg of body weight. There was a steady increase with maximum requirement observed on day 4 and decreased thereafter to 0.33 units per kg of body weight on day 5. For GDM women in Group B, only three maintained their insulin dose (Group B1; n=3/14) while 11 (Group B2; n=11/14) women with GDM previously on insulin, required further increase in insulin from day 1-2 reaching 140% increase in insulin dose on day 2. Thereafter, there was a gradual decrease of insulin dose almost returning to initial dose on day 5.

Insulin initiation was observed among GDM diet-controlled mothers (Group A) who were given ACS therapy at ≥31 weeks age of gestation. Age, parity, family history of diabetes and mode of delivery did not have significant effects on insulin use nor increased insulin requirement. Fasting capillary glucose (FCG) and one-hour post-prandial capillary glucose (PPCG) were elevated within 24 hours after administration of corticosteroid (betamethasone) in 60%-70% of our population. The FCG values remained elevated on day 2-3 in about 70% of patients. While the first hour PPCG was elevated in 85% of patients on day 2 and remained elevated in 70% of women on day 3-4, it reached 53% on day 5. Insulin requirement among Group B2 reached to 140% increase in insulin dose on day 2 followed by a gradual decrease of insulin dose almost returning to initial dose on day 5.

ACS administration caused maternal hyperglycemia in Filipino women with GDM during the first 24 hours and lasting up to five days. Both fasting glucose and post-prandial glucose were elevated, hence intensified monitoring of maternal glucose levels and temporary addition or increase of insulin doses may be necessary. The timing (≥31 weeks AOG) of administration of ACS on GDM women was associated with subsequent insulin initiation but only on patients initially controlled on diet alone.