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]

References20Show ledgerHide ledger

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
3. [3]Jensen DM, Korsholm L, Ovesen P, et al. Peri-conceptional A1C and risk of serious adverse pregnancy outcome in 933 women with type 1 diabetes. Diabetes Care, 2009.PMID 19265024
4. [4]Macintosh MC, Fleming KM, Bailey JA, et al. Perinatal mortality and congenital anomalies in babies of women with type 1 or type 2 diabetes in England, Wales, and Northern Ireland: population based study. BMJ, 2006.PMID 16782722
5. [5]Wahabi HA, Alzeidan RA, Bawazeer GA, et al. Preconception care for diabetic women for improving maternal and fetal outcomes: a systematic review and meta-analysis. BMC Pregnancy Childbirth, 2010.PMID 20946676
6. [6]Feig DS, Donovan LE, Corcoy R, et al. Continuous glucose monitoring in pregnant women with type 1 diabetes (CONCEPTT): a multicentre international randomised controlled trial. Lancet, 2017.PMID 28923465
7. [7]Feig DS, Donovan LE, Zinman B, et al. Metformin in women with type 2 diabetes in pregnancy (MiTy): a multicentre, international, randomised, placebo-controlled trial. Lancet Diabetes Endocrinol, 2020.PMID 32946820
8. [8]Feig DS, Sanchez JJ, Murphy KE, et al. Outcomes in children of women with type 2 diabetes exposed to metformin versus placebo during pregnancy (MiTy Kids): a 24-month follow-up of the MiTy randomised controlled trial. Lancet Diabetes Endocrinol, 2023.PMID 36746160
9. [9]Mathiesen ER, Hod M, Ivanisevic M, et al. Maternal efficacy and safety outcomes in a randomized, controlled trial comparing insulin detemir with NPH insulin in 310 pregnant women with type 1 diabetes. Diabetes Care, 2012.PMID 22851598
10. [10]Mathiesen ER, Alibegovic AC, Corcoy R, et al. Insulin degludec versus insulin detemir, both in combination with insulin aspart, in the treatment of pregnant women with type 1 diabetes (EXPECT): an open-label, multinational, randomised, controlled, non-inferiority trial. Lancet Diabetes Endocrinol, 2023.PMID 36623517
11. [11]Widyaputri F, Khong EWC, Rogers SL, et al. Progression of diabetic retinopathy in women with pregestational diabetes during pregnancy and postpartum. Clin Exp Ophthalmol, 2024.PMID 38895754
12. [12]Bourry J, Courteville H, Ramdane N, et al. Progression of Diabetic Retinopathy and Predictors of Its Development and Progression During Pregnancy in Patients With Type 1 Diabetes: A Report of 499 Pregnancies. Diabetes Care, 2021.PMID 33177172
13. [13]Ringholm L, Damm JA, Vestgaard M, et al. Diabetic Nephropathy in Women With Preexisting Diabetes: From Pregnancy Planning to Breastfeeding. Curr Diab Rep, 2016.PMID 26803648
14. [14]Rolnik DL, Wright D, Poon LC, et al. Aspirin versus Placebo in Pregnancies at High Risk for Preterm Preeclampsia. N Engl J Med, 2017.PMID 28657417
15. [15]Biesty LM, Egan AM, Dunne F, et al. Planned birth at or near term for improving health outcomes for pregnant women with pre-existing diabetes and their infants. Cochrane Database Syst Rev, 2018.PMID 29423911
16. [16]Gordon HG, Shub A, Walker SP, et al. Maternal Diabetes, Fetal Growth, and Stillbirth Risk: A Population-Wide Retrospective Cohort Study From Victoria, Australia. Diabetes Care, 2025.PMID 40902109
17. [17]Jones A, Gong JY, Lee IL, et al. Proactive Insulin Escalation for Antenatal Betamethasone-Induced Hyperglycaemia in Women With Diabetes: A Prospective Cohort Study. Aust N Z J Obstet Gynaecol, 2025.PMID 40242934
18. [18]ElSayed NA, Aleppo G, Aroda VR, et al. 15. Management of Diabetes in Pregnancy: Standards of Care in Diabetes-2023. Diabetes Care, 2023.PMID 36507645
19. [19]Benhalima K, Durnwald C, Sweeting A, et al. Application of continuous glucose monitoring and automated insulin delivery technologies for pregnant women with type 1, type 2, or gestational diabetes: an international consensus statement. Lancet Diabetes Endocrinol, 2026.PMID 41421368
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