Antenatal corticosteroids (ACS) are recommended for mothers at risk of preterm delivery before 34 weeks gestation to improve foetal outcome and prevent respiratory distress. The antenatal corticosteroid of choice is betamethasone in two divided doses. The administration of steroids results in episodes of hyperglycaemia of up to 5 days duration which can be a problem for mothers with pre-existing diabetes or gestational diabetes mellitus. To counteract this, insulin is administered to reduce blood glucose levels, however there is no national protocol dictating the optimal mode of insulin delivery or dose escalation in these circumstances.
The aim of this study will be to identify the optimal dosing of insulin to gain the best control of blood glucose after administering the corticosteroid injection. In addition, different hospitals within the same hospital group (Saolta) administer the same dose of betamethasone at different time intervals (either 12 hours or 24 hours apart). We will also look at the effect of the 12 hour interval on glucose levels and if time allows compare it to the 24 hour interval dosing. This prospective cohort study will analyse the percentage of pre- and post-prandial readings above pregnancy targets in the 5 days post administration of the 2nd dose ACS in women with T1DM/T2DM and GDM. We will use an algorithm adopted by the Canadian Diabetes in Pregnancy guidelines which actively increases insulin doses to counteract the expected physiological glycaemic response to steroid administration. We will record the number of women who deliver prior to the administration of the second dose and look at neonatal outcomes, including respiratory distress syndrome and neonatal hypoglycaemia. A cost analysis will be conducted to determine the cost savings of using the algorithm versus the traditional use of variable rate insulin infusion.
