Diastolic blood pressure is a potentially modifiable risk factor for preeclampsia in women with pre-existing diabetes.

Aims: To identify early clinical, modifiable risk factors for preeclampsia present at first antenatal visit and assess the prevalence of pregnancy-related hypertensive disorders in women with pre-existing diabetes treated with tight glycemic and blood pressure (BP) control.
Methods: A population-based cohort study of 494 women with pre-existing diabetes (307 and 187 women with type 1 and type 2 diabetes, respectively), included at their first antenatal visit from 2012 to 2016. The prevalence of chronic hypertension (without diabetic nephropathy or microalbuminuria), gestational hypertension and preeclampsia was recorded. Diabetic microangiopathy included presence of nephropathy, microalbuminuria and/or retinopathy. Treatment target was BP <135/85 mmHg.
Results: HbA1c was 6.9 ± 2.4% (50 ± 12 mmol/mol) at first antenatal visit and 6.0 ± 0.6% (43 ± 6 mmol/mol) before delivery with no differences between women with type 1 and type 2 diabetes. At the first antenatal visit, the prevalence of microalbuminuria was 6% (6% vs. 6%), nephropathy 2% (1% vs. 2%) and chronic hypertension 6% (3% vs. 10%, p = 0.03). Gestational hypertension developed in 8% (9% vs. 6%) and preeclampsia developed in 8% (9% vs. 7%). Presence of diabetic microangiopathy (adjusted odds ratio (OR) 4.35 (confidence interval 2.12-8.93)) and diastolic BP (adjusted OR 1.72 per 10 mmHg (1.05-2.82)) at the first antenatal visit were independent risk factors for preeclampsia.
Conclusions: At the first antenatal visit, diastolic BP was the only independent, potentially modifiable risk factor for preeclampsia in women with pre-existing diabetes in the context of tight glycemic and BP control. One out of four women had hypertensive disorders during pregnancy.
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