A protocol for improved glycaemic control following corticosteroid therapy in diabetic pregnancies

Diabetic pregnancies have an increased risk of respiratory distress syndrome (RDS) and preterm delivery. Antenatal corticosteroids can prevent RDS but induce acute severe hyperglycaemia. We have developed a protocol which prevents hyperglycaemia and can be used easily by ward staff.

Intramuscular dexamethasone is given in two doses 12 h apart. Subcutaneous insulin and diet are continued but from the first dexamethasone dose until 12 h after the second, supplementary intravenous insulin is infused according to hourly blood glucose measurements. The protocol incorporates four graded sliding scales. The initial scale is selected according to the patient's current subcutaneous insulin dose and advanced if the blood glucose is > or = 10.1 mmol/l for 2 consecutive hours.

In a 10-month period eight (three gestational, five pre-gestational) women received antenatal corticosteroids from a total of 37 diabetic pregnancies. The median amount of supplementary intravenous insulin required was 74 U (range 32-88 U); the median glucose values achieved were 5.8-8.9 mmol/l. Seventy-five percent of glucose measurements were within an acceptable range of 4-10 mmol/l. Only one baby developed RDS.

Large amounts of supplementary intravenous insulin are needed to achieve even moderate glycaemic control. This protocol enables routine ward staff to manage this successfully.