Diabetic ketoacidosis develops at lower glucose concentrations in pregnancy, sometimes with glucose only modestly raised, because pregnancy increases insulin resistance and ketogenesis while lowering bicarbonate buffering. Fetal loss in maternal ketoacidosis remains substantial.
A woman with type 1 or type 2 diabetes in pregnancy who has vomiting, abdominal pain or an intercurrent infection needs blood ketones and a venous gas, whatever her glucose meter reads. The same applies to anyone who recently stopped an SGLT2 inhibitor on learning of a pregnancy.
- Measure blood ketones in any pregnant woman with diabetes who is vomiting or unwell, even with near-normal glucose.
- Check a venous gas and bicarbonate when ketones are raised.
- Do not use a normal glucose reading to rule out ketoacidosis in pregnancy.
- Give sick-day rules, including when to test ketones, at the first antenatal diabetes visit.
Why it matters
A reassuring glucose is the commonest reason maternal ketoacidosis is recognised late.
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