Pregestational diabetes (type 1 and type 2) in pregnancy

She is 27, has had type 1 diabetes since she was nine, and she is 11 weeks pregnant. She stopped her ramipril last week because a pharmacist told her to. Her HbA1c is 9.2 percent. Everything that will determine whether this baby has a heart defect has already happened. That uncomfortable sentence is why this topic is really a preconception topic wearing antenatal clothes.^[3][5]

Overview and definition

Pregestational diabetes means diabetes that existed before the pregnancy — type 1, type 2, monogenic or secondary. In practice you also manage overt diabetes in pregnancy the same way: hyperglycaemia found antenatally that reaches diabetes-level thresholds, which almost always turns out to be undiagnosed type 2 disease.^[1][2]

The distinction that changes your plan is not the label on the chart. It is these three questions: ^[1][18]

• Is she insulin-deficient? Type 1 diabetes brings ketosis risk, hypoglycaemia unawareness and an absolute requirement for basal insulin.
• How much microvascular disease is there already? Retinopathy and nephropathy determine surveillance, preeclampsia risk and timing of birth far more than the diabetes type does.
• What technology is she on? Injections, pump, continuous glucose monitoring or a closed-loop system each carry different evidence and different failure modes in pregnancy.^[1][19]

References20ShowHide

1. [1]Rudland VL, Price SAL, Callaway L ADIPS position paper on pre-existing diabetes and pregnancy. Aust N Z J Obstet Gynaecol, 2020.PMID 33135798
2. [2]Rudland VL, Price SAL, Hughes R, et al. ADIPS 2020 guideline for pre-existing diabetes and pregnancy. Aust N Z J Obstet Gynaecol, 2020.PMID 33200400
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20. [20]Donovan LE, Lemieux P, Dunlop AD, et al. Closed-Loop Insulin Delivery in Type 1 Diabetes in Pregnancy: The CIRCUIT Randomized Clinical Trial. JAMA, 2025.PMID 41134589