Falling Third Trimester Insulin Requirements and Adverse Pregnancy Outcomes in Individuals with Pre-Existing Diabetes: A Retrospective Cohort Study

Vainder, Marina; Natt, Navneet; Sayyar, Parastoo; Syeda, Ambreen; Ashraf, Rizwana; Mitsakakis, Nicholas; Feig, Denice S.; Kingdom, John; D’Souza, Rohan

doi:10.3390/jcm14217737

Open AccessArticle

Falling Third Trimester Insulin Requirements and Adverse Pregnancy Outcomes in Individuals with Pre-Existing Diabetes: A Retrospective Cohort Study

by

Marina Vainder

¹

,

Navneet Natt

¹,

Parastoo Sayyar

¹,

Ambreen Syeda

¹,

Rizwana Ashraf

^2,3,

Nicholas Mitsakakis

⁴,

Denice S. Feig

^5,6,

John Kingdom

¹ and

Rohan D’Souza

^1,2,3,*

¹

Department of Obstetrics and Gynaecology, Mount Sinai Hospital, University of Toronto, Toronto, ON M5G 1X5, Canada

²

Department of Obstetrics and Gynaecology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L8, Canada

³

Department of Health Research Methods Evidence and Impact, McMaster University, Hamilton, ON L8S 4L8, Canada

⁴

Clinical Research Unit, Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada

⁵

Department of Medicine, Division of Endocrinology, University of Toronto, Toronto, ON M5S 3H2, Canada

⁶

Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, ON M5T 3M6, Canada

^*

Author to whom correspondence should be addressed.

J. Clin. Med. 2025, 14(21), 7737; https://doi.org/10.3390/jcm14217737

Submission received: 25 July 2025 / Revised: 13 October 2025 / Accepted: 29 October 2025 / Published: 31 October 2025

(This article belongs to the Special Issue Clinical Updates on Maternal Fetal Medicine)

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Abstract

Objective: To determine whether a third-trimester drop in insulin requirements in pregnant people with pre-existing diabetes is associated with a subsequent occurrence of adverse pregnancy outcomes. Research Design and Methods: We conducted a retrospective cohort study of patients with type 1 and 2 diabetes who were followed at a tertiary referral center in Toronto, Canada. We collected data on insulin dosing in the third trimester (after 28 weeks of pregnancy) and compared outcomes in those with and without a third-trimester drop of 15% or more in their total insulin requirements. Our primary outcome was a composite of stillbirth, spontaneous preterm birth or preterm premature rupture of membranes, and iatrogenic preterm birth or cesarean birth for fetal wellbeing concerns, occurring following the drop in insulin requirements. We conducted regression analyses controlling for early pregnancy glycosylated hemoglobin, body mass index, and diabetes-related microvascular disease, and presented results as odds ratios (OR) with 95% confidence intervals (95%CI). Results: We included 350 pregnant people—146 with type 1 and 204 with type 2 diabetes. Of these, 54 (15.4%) had a third-trimester drop of 15% or more in their total insulin requirements. There was no difference in the primary outcome between groups (OR 0.97; 95% CI 0.41–2.10). Conclusions: Based on this single-center study, limited by sample size and analytic constraints, in people with pre-existing diabetes, a third-trimester drop of ≥15% in total insulin requirements was not associated with subsequent occurrence of adverse pregnancy outcomes. Larger prospective studies looking at associations between a drop in insulin requirements and subsequent occurrence of adverse pregnancy outcomes are necessary to inform meta-analyses and clinical decision making.

Keywords: type 1 diabetes; type 2 diabetes; diabetes in pregnancy; insulin requirement

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MDPI and ACS Style

Vainder, M.; Natt, N.; Sayyar, P.; Syeda, A.; Ashraf, R.; Mitsakakis, N.; Feig, D.S.; Kingdom, J.; D’Souza, R. Falling Third Trimester Insulin Requirements and Adverse Pregnancy Outcomes in Individuals with Pre-Existing Diabetes: A Retrospective Cohort Study. J. Clin. Med. 2025, 14, 7737. https://doi.org/10.3390/jcm14217737

AMA Style

Vainder M, Natt N, Sayyar P, Syeda A, Ashraf R, Mitsakakis N, Feig DS, Kingdom J, D’Souza R. Falling Third Trimester Insulin Requirements and Adverse Pregnancy Outcomes in Individuals with Pre-Existing Diabetes: A Retrospective Cohort Study. Journal of Clinical Medicine. 2025; 14(21):7737. https://doi.org/10.3390/jcm14217737

Chicago/Turabian Style

Vainder, Marina, Navneet Natt, Parastoo Sayyar, Ambreen Syeda, Rizwana Ashraf, Nicholas Mitsakakis, Denice S. Feig, John Kingdom, and Rohan D’Souza. 2025. "Falling Third Trimester Insulin Requirements and Adverse Pregnancy Outcomes in Individuals with Pre-Existing Diabetes: A Retrospective Cohort Study" Journal of Clinical Medicine 14, no. 21: 7737. https://doi.org/10.3390/jcm14217737

APA Style

Vainder, M., Natt, N., Sayyar, P., Syeda, A., Ashraf, R., Mitsakakis, N., Feig, D. S., Kingdom, J., & D’Souza, R. (2025). Falling Third Trimester Insulin Requirements and Adverse Pregnancy Outcomes in Individuals with Pre-Existing Diabetes: A Retrospective Cohort Study. Journal of Clinical Medicine, 14(21), 7737. https://doi.org/10.3390/jcm14217737

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Falling Third Trimester Insulin Requirements and Adverse Pregnancy Outcomes in Individuals with Pre-Existing Diabetes: A Retrospective Cohort Study

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