Antenatal dexamethasone vs betamethasone on glycemic control in mild gestational diabetes: a randomized clinical trial

Abstract

BACKGROUND

Preterm birth and gestational diabetes mellitus are common complications of pregnancy. A widely known side effect of antenatal corticosteroids on fetal maturity in preterm births is maternal hyperglycemia. The choice of antenatal corticosteroid regimens between dexamethasone and betamethasone highly depends on local availability and cost, as current but inconclusive evidence shows similar neonatal outcomes for both regimes.

OBJECTIVE

This study aimed to compare four 6.0-mg doses of antenatal dexamethasone administered 12 hours apart vs two 11.4-mg doses of antenatal betamethasone administered 24 hours apart in medical nutrition therapy–controlled gestational diabetes mellitus cases on maternal glycemic response for up to 3 consecutive days after administration.

STUDY DESIGN

This was a randomized controlled clinical trial conducted between February 2021 and August 2023 at a tertiary university hospital in Malaysia. Pregnant participants with diet-controlled gestational diabetes mellitus and prescribed antenatal corticosteroid were randomized to either four 6.0-mg doses of dexamethasone administered 12 hours apart or two 11.4-mg doses of betamethasone administered 24 hours apart. Self-monitoring of capillary blood glucose level (6 points per 24 hours: 2 hours before and after a meal for the 3 main meals) was started after the first dose of allocated antenatal corticosteroid. Hyperglycemia was defined as a fasting or premeal glucose level of ≥5.3 mmol/L (≤95 mg/dL) or a 2-hour postmeal glucose level of ≥6.7 mmol/L (120 mg/dL). The primary outcomes were number of hyperglycemic episodes within the first and second 24 hours after antenatal corticosteroid administration. Analyses were performed using the t test, Mann-Whitney U test, and chi-square test, as appropriate.

RESULTS

The median hyperglycemic episodes were similar between the dexamethasone group and the betamethasone group: 4.0 (interquartile range, 2.3–5.0) vs 4.0 (interquartile range, 3.5–5.0), respectively, on day 1 (P=.168), 4.0 (interquartile range, 3.0–5.0) vs 5.0 (interquartile range, 4.0–5.0), respectively, on day 2 (P=.002), and 1.0 (interquartile range, 0.0–2.0) vs 2.0 (interquartile range, 1.0–3.0), respectively, on day 3 (P<.001). In addition, the median blood glucose levels were significantly lower in the dexamethasone group than in the betamethasone group on days 1, 2, and 3 (day 1: 6.3 [interquartile range, 5.8–7.0] vs 6.7 [interquartile range, 6.3–7.0], respectively; P=.016; day 2: 6.4 [interquartile range, 6.0–6.9] vs 6.7 [interquartile range, 6.3–7.2], respectively; P=.001; day 3: 5.2 [interquartile range, 4.8–5.5] vs 5.7 [interquartile range, 5.4–6.0], respectively; P<.001). The mean blood glucose levels were higher in the betamethasone group than in the dexamethasone group on day 1 to 3 (6.2 mmol/L [97.5% confidence interval, 6.0–6.4] vs 6.6 mmol/L [97.5% confidence interval, 6.4–6.7], respectively; mean difference, −0.374 [97.5% confidence interval, −0.521 to −0.226], respectively; P<.001). Other maternal and neonatal outcomes were not significantly different between the groups.

CONCLUSION

In gestational diabetes mellitus on medical nutrition therapy, dexamethasone antenatal corticosteroid therapy could be preferred over betamethasone, as hyperglycemic episodes on days 2 and 3 after treatments were fewer and the median blood glucose levels were lower on day 1 to day 3.