Proactive Insulin Escalation for Antenatal Betamethasone-Induced Hyperglycaemia in Women With Diabetes: A Prospective Cohort Study.

Background: In patients with diabetes, antenatal glucocorticoids can induce transient maternal hyperglycaemia for approximately 72 h. This may be associated with adverse outcomes, including neonatal hypoglycaemia, prompting recommendations for prophylactic increases in insulin by some expert groups; however, there are no validated protocols. A review of our institutional practice of empiric dose escalation (Day 1:25%, Day 2-3:40%, Day 4:20%, Day 5:10%) determined it was inadequate to prevent hyperglycaemia.

Aim: To investigate the efficacy of an intensified insulin escalation protocol in achieving time in target range (3.9-7.8 mmol/L) following antenatal betamethasone.

Materials and methods: Following implementation of the intensified insulin escalation protocol at Western Health (Day 1 and 2: 50% increase, Day 3:30% increase), a prospective cohort study was conducted for women with gestational diabetes or type 2 diabetes managed with insulin requiring betamethasone. Data was collected from the electronic medical record and expressed as mean ± SD or median (IQR).

Results: 29 women (82.8% GDM, 17.2% T2DM) were included with median gestation 33 + 2 (31-34⁺⁴) weeks and median BMI 30 kg/m² (27-38IQR). In the 72 h post first-dose betamethasone, the proportion of readings in target range (< 5.1 mmol/L fasting and < 6.8 mmol/L post prandial) was 35.3%. There was no maternal hypoglycaemia. Median increase in insulin requirement was 50% (22.6%-100% IQR) on Day 1, 106% on Day 2 (33%-297% IQR) and 133% on Day 3 (23%-543% IQR).

Conclusions: A significant increase in insulin requirement, exceeding current guideline recommendations, occurs following antenatal betamethasone in women with diabetes, and further prospective evaluation of optimal dosing is required.