Higher Type 1 Diabetes Glycemia Links to More Preeclampsia

Miriam E. Tucker

December 27, 2022

Researchers published the study covered in this summary on Preprints with The Lancet as a preprint that has not yet been peer reviewed.

Key Takeaways

  • Women with type 1 diabetes (T1D) have a higher risk of developing preeclampsia compared with women without any form of diabetes.

  • The relative risk for preeclampsia in women with type 1 diabetes increases in a dose-dependent manner as A1c levels increase.

  • There is a significant health benefit in maintaining periconceptional normoglycemia.

Why This Matters

  • The relationship between type 1 diabetes, glycemia, and preeclampsia has not been well-studied. No large-scale studies have assessed the impact of glycemic control at the time of conception on preeclampsia risk.

Study Design

  • This was a population-based cohort study using nationwide diabetes and birth registries in Sweden during 2003-2014, including data for 2481 (0.21%) singleton pregnancies to 2035 women with T1D and 1,167,540 singleton pregnancies to 747,305 women without T1D (99.79%).

  • The authors defined pregestational diagnosis of type 1 diabetes as diagnosis at any time before the start of the included singleton pregnancy and up to 91 days after pregnancy start, with at least one registered A1c value anytime within the period of 90 days before pregnancy to 91 days after conception.

Key Results

  • Preeclampsia occurred in 15.7% of the pregnancies in women with type 1 diabetes and in 2.9% of women without diabetes.

  • The incidence of preeclampsia increased in women with type 1 diabetes in a dose-dependent pattern as periconceptional A1c increased. The incidence of preeclampsia was 10.3% in women with type 1 diabetes and an A1c no greater than 6.4%, and 21.5% among those with an A1c of 9.1% or higher.

  • The adjusted risk ratio (RR) for developing preeclampsia overall anytime during pregnancy among women with type 1 diabetes compared with women without diabetes was a significant 4.47.

  • The adjusted RR of preeclampsia compared with women without diabetes also increased in a dose-dependent manner across increasing strata of A1c, ranging from 3.11 for those with an A1c no greater than 6.4% to 5.76 for those with an A1c of at least 9.1%.


  • The authors did not have access to A1c data for all women with type 1 diabetes just prior to their pregnancy, a possible selection bias.

  • Women with type 1 diabetes and poor glycemic control may not have been included because their poor control may have led to miscarriage, another possible bias in the study population.

  • The findings may not be generalizable to non-Swedish populations.


  • The study received no commercial funding.

  • None of the authors had disclosures.

This is a summary of the preprint research study "Maternal Glycaemic Control in Pre-Gestational Type 1 Diabetes and Pre-Eclampsia Risk: A Population-Based Cohort Study in Sweden,” written by researchers primarily at the Karolinska Institute in Stockholm, Sweden, on Preprints with The Lancet provided to you by Medscape. The study has not yet been peer-reviewed. The full text of the study can be found on ssrn.com.

For more news, follow Medscape on  Facebook,   Twitter,   Instagram, and  YouTube.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.