Association Between Maternal Glucose Levels in Gestational Diabetes Screening and Subsequent Hypertension.

BACKGROUND

We assessed the association between maternal glucose levels in pregnancy and subsequent hypertension.

METHODS

This population-level, retrospective cohort study examined women aged 12 to 54 years with singleton pregnancies completed at ≥29 weeks of gestation from October 1, 2008 to December 1, 2018 followed until March 31, 2019 in Alberta, Canada. Women were stratified by results in the 50-gram glucose challenge test and by 75-gram oral glucose tolerance test subtypes (normal oral glucose tolerance test, elevated fasting plasma glucose only [elevated fasting], elevated postload glucose only, or both elevated fasting and postload glucose [combined]. Time to development of hypertension was modeled using Cox proportional hazards models.

RESULTS

Of 313 361 women, 231 008 (79.1%) underwent a glucose challenge test only while 60 909 (20.9%) underwent either an oral glucose tolerance test only or both. Nine thousand five hundred eighty (3.1%) developed hypertension, and 2824 (0.9%) developed cardiovascular disease over a median follow-up of 5.7 years. Every 1-mmol/L increase in glucose in the glucose challenge test increased the risk of subsequent hypertension by 15% (adjusted hazard ratio and 95% CI, 1.15 [1.14-1.16]). Among those who underwent the oral glucose tolerance test, the combined group conferred the highest risk of subsequent hypertension, followed by elevated fasting, then elevated postload glucose only (reference: glucose challenge test ≤7.1 mmol/L, adjusted hazard ratio [95% CI]: elevated postload glucose only, 1.83 [1.68-2.00]; elevated fasting 2.02 [1.70-2.40]; combined, 2.65 [2.33-3.01]). No significant associations between maternal glucose levels and cardiovascular disease were observed.

CONCLUSIONS

Increasing maternal glucose levels in pregnancy were associated with increasing risk of subsequent hypertension. These findings may help identify higher-risk women who should be targeted for earlier postpartum cardiovascular risk reduction.