Impact of different hypertensive disorders of pregnancy on cardiovascular disease risk and all-cause mortality in women with type 1 diabetes.

Objectives: Our aim was to assess how pre-eclampsia, gestational hypertension, and chronic (pre-pregnancy) hypertension, compared to no hypertensive disorders during pregnancy, impact development of cardiovascular disease and all-cause mortality in type 1 diabetes (T1D).

Methods: We included 190 T1D women with median age of 29.4 (interquartile range 26.0-33.3) years at delivery between 1988 and 1994 at the Helsinki University Hospital, and who were later re-examined within the Finnish Diabetic Nephropathy Study. Of these, 43 (22.6%) had had pre-eclampsia, 32 (16.8%) gestational hypertension, 20 (10.5%) chronic hypertension, and 95 (50.0%) had remained normotensive during the index pregnancy. We retrieved follow-up data on cardiovascular events and mortality from national registries until the end of 2020.

Results: During a median 27.9 (25.4-30.7) years of follow-up, 46 (24.2%) experienced a composite cardiovascular event and 25 (13.2%) died from any cause. In Cox regression analysis, the risk of a cardiovascular event was increased for chronic hypertension [hazard ratio, HR 3.45 (95% CI 1.25-9.54)], gestational hypertension [HR 3.63 (1.55-8.51)], and pre-eclampsia [HR 5.07 (2.31-11.11)] compared with the non-hypertension group, after adjustment for delivery age and age at T1D onset. The corresponding risk of all-cause mortality was increased for chronic hypertension [HR 3.31 (1.06-10.35)] and pre-eclampsia [HR 2.92 (1.07-7.98)], but not for gestational hypertension [HR 1.26 (0.33-4.85)]. After further adjustment for diabetic kidney disease or diabetic retinopathy as a time-dependent covariate, the association with cardiovascular disease remained for pre-eclampsia and gestational hypertension, while for mortality, none of the associations were significant.

Conclusion: Hypertension during pregnancy is associated with increased risk of cardiovascular events during long-term follow-up in women with T1D, with pre-eclampsia conferring the highest risk. For all-cause mortality, chronic hypertension and pre-eclampsia, but not gestational hypertension, increases the risk of death, yet not independently of diabetic kidney disease.