Glycaemic Control in Women With Type 1 Diabetes and Preeclampsia Risk: A Nationwide Cohort Study

Natalie Holowko; Nathalie Roos; Björn Pasternak; Jonas Söderling; Martin Neovius; Soffia Gudbjörnsdottir; Anna Sandström; Jonas F Ludvigsson; Olof Stephansson

doi:10.1111/1471-0528.18339

Glycaemic Control in Women With Type 1 Diabetes and Preeclampsia Risk: A Nationwide Cohort Study

BJOG. 2025 Aug 26. doi: 10.1111/1471-0528.18339. Online ahead of print.

Authors

Natalie Holowko^{1

2

3}, Nathalie Roos¹, Björn Pasternak^{1

4}, Jonas Söderling¹, Martin Neovius^{1

5}, Soffia Gudbjörnsdottir⁶, Anna Sandström^{1

2}, Jonas F Ludvigsson^{5

7}, Olof Stephansson^{1

2}

Affiliations

¹ Clinical Epidemiology Division, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden.
² Division of Obstetrics and Gynaecology, Karolinska University Hospital, Stockholm, Sweden.
³ The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Victoria, Australia.
⁴ Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark.
⁵ Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
⁶ Department of Molecular and Clinical Medicine, Sahlgrenska Academy, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden.
⁷ Department of Paediatrics, Örebro University Hospital, Örebro, Sweden.

PMID: 40856153
DOI: 10.1111/1471-0528.18339

Abstract

Objective: No large-scale studies exist investigating glycaemic control around conception and preeclampsia risk.

Design: Population-based nationwide cohort study using the National Diabetes Register and other health registers.

Setting: Sweden.

Population: Singleton pregnancies between 2003 and 2019 (N = 1 689 301); 4429 with type 1 diabetes (T1DM) and 1 684 872 without.

Methods: The main exposure was having a pre-gestational diagnosis of T1DM (first diagnosis anytime ≤ 91 days after conception and ≥ 1value of glycated haemoglobin (HbA1c) within ±90 days from conception). Peri-conceptional glycaemic control was categorised using the most recent HbA1c measurement (mmol/mol: < 48; 48-61; 62-75; ≥ 76). Unexposed were women without any diabetes diagnosis (≤ 91 days after conception).

Main outcome measures: Preeclampsia was defined using ICD codes and further categorised according to completed gestational weeks at delivery with preeclampsia diagnosis: early preterm preeclampsia (< 34 + 0), late preterm preeclampsia (34 + 0 to 36 + 6), or term preeclampsia (≥ 37 + 0).

Results: 16.8% of women with T1DM developed preeclampsia, compared to 2.9% of women without diabetes (adjusted RR [aRR] 4.7, 95% CI 4.4-5.0). Preeclampsia risk increased with peri-conceptional HbA1c, from 11.6% in women with HbA1c < 48 mmol/mol to 23.3% in women with HbA1c ≥ 76 mmol/mol. Compared to unexposed women, there was a dose-response relationship between HbA1c and preeclampsia in women with T1DM (HbA1c < 48 mmol/mol aRR 3.4 (2.9-4.0); HbA1c 48-61 mmol/mol aRR 4.6 (4.2-5.1); HbA1c 62-75 mmol/mol aRR 5.7 (5.0-6.5): HbA1c ≥ 76 mmol/mol aRR 6.3 (CI 5.3-7.7)). Compared to unexposed women, the aRR of term preeclampsia was 3.5 times higher (3.1-3.9) in women with T1DM, while the aRR was much higher for early preterm preeclampsia (aRR 7.2: 6.1-8.5) and late preterm preeclampsia (aRR 9.9: 8.8-11.1).

Conclusions: Women with T1DM had a higher risk of preeclampsia, which increased in a dose-response manner with poorer peri-conceptional glycaemic control.

Keywords: diabetes mellitus; hypertension; preeclampsia; pregnancy; pregnancy complications; pregnancy‐induced; type 1.

Abstract

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