Gestational Glucose Intolerance and the Risk of Hypertensive Disorders of Pregnancy

BACKGROUND: We evaluated associations between untreated mild hyperglycemia and hypertensive disorders of pregnancy. METHODS: In this retrospective study at a US academic medical center practicing universal 2-step gestational diabetes (GD) testing, we defined normal glucose tolerance as a normal screening 50-g, 1-hour glucose load test (<140 mg/dL). If the glucose loading test was abnormal, a diagnostic 100-g, 3-hour oral glucose tolerance test was performed. We defined GD as ≥2 abnormal oral glucose tolerance test values (Carpenter-Coustan criteria) and gestational glucose intolerance (GGI, untreated subclinical hyperglycemia) as 0 (GGI-0) or 1 (GGI-1) abnormal oral glucose tolerance test value. We divided GD into treated and untreated (given use of older diagnostic criteria in the study period). We examined associations between GGI or GD and hypertensive disorders of pregnancy (primary outcome) or its subtypes (gestational hypertension, preeclampsia) using generalized estimating equations with confounder adjustment. RESULTS: Among 41 484 pregnancies, 84% had normal glucose tolerance, 12% had GGI (GGI-0: 9.0%, GGI-1: 3.0%) and 3.5% had GD. There was greater risk of hypertensive disorders of pregnancy in GGI compared with normal glucose tolerance (adjusted odds ratio [aOR], 1.24 [95% CI, 1.11-1.38]). This was attributable to increased risk in GGI-1 (aOR, 1.53 [95% CI, 1.27-1.85]), similar to untreated GD (aOR, 1.76 [95% CI, 1.37-2.26]). The risk of gestational hypertension was increased in GGI-1 (aOR, 1.66 [95% CI, 1.30-2.12]) and untreated GD (aOR, 1.89 [95% CI, 1.36-2.63]) but not in treated GD (aOR, 0.84 [95% CI, 0.58-1.23). The risk of preeclampsia was similarly increased in GGI-1, treated GD, and untreated GD (aOR, 1.46-1.75). CONCLUSIONS: Mild untreated hyperglycemia in pregnancy is associated with hypertensive disorders of pregnancy; hyperglycemia treatment is associated with reduced gestational hypertension risk.