Pregnant women with diabetes are much more prone to diabetic ketoacidosis due to the combination of insulin resistance and accelerated catabolism of pregnancy. Initiating factors are the same as those for any person with diabetes and include vomiting, infections, failure of insulin administration or failure to meet increasing insulin requirements. Ketoacidosis in pregnancy must be treated with the utmost urgency as fetal loss occurs in almost 50% of cases. Patients are best managed on a medical intensive care unit along conventional lines but with close fetal monitoring. Adequate fluid and potassium replacement is essential in conjunction with intravenous insulin infusion, adjusted to achieve a smooth reduction of plasma glucose concentration. Initial rehydration should be with normal saline; this should be changed to 10% dextrose, once the blood glucose is less than 10 mmol/L and continued until the patient is free of ketones.
The use of corticosteroids in premature labour before 34 weeks of gestation to accelerate fetal lung maturation may dramatically increase insulin resistance. Similarly, the use of intravenous β sympathomimetic agents to treat premature uterine contractions will cause severe hyperglycaemia and ketoacidosis unless appropriately anticipated. Careful glucose monitoring should always accompany this form of treatment and aggressive intravenous insulin treatment must be started if necessary.