Insulin resistance and pregnancy outcomes in gestational diabetes mellitus gravida complicated by chronic hypertension

Objective To analyze insulin resistance (IR) level and pregnancy outcomes in women with gestational diabetes mellitus (GDM) complicated by chronic hypertension (CHT). Methods This is a retrospective case-control study involving 2 457 singleton pregnant women complicated by GDM who received regular prenatal examinations and participated in the one-day-care clinic of GDM in Peking University First Hospital from January 1, 2014 to December 31, 2016. Clinical data were collected and homeostasis model assessment insulin resistance (HOMA-IR) was calculated. All subjects were divided into two groups: GDM with CHT group (CHT group, n=47) and GDM without CHT group (non-CHT group, n=2 410). Based on their pre-pregnancy body mass index (BMI), they were also grouped into normal pre-pregnancy BMI group (n=1 590) and overweight and obese group (n=863). Two-sample independent t test and Chi-square test were used to compared the age, HOMA-IR, pre-pregnancy BMI, weight gain during pregnancy and glucose levels between groups, and logistic regression model was used to analyze the effects of HOMA-IR on pregnancy outcomes. Results HOMA-IR (3.5±1.8 vs 2.6±1.5, t=-3.290), fasting plasma glucose [(5.4±0.5) vs (5.2±0.5) mmol/L, t=-3.005], pre-pregnancy BMI [(26.7±4.7) vs (23.3±3.4) kg/m2, t=-4.842] and the incidence of preeclampsia [14.9% (7/47) vs 2.5% (61/2 410), χ2=21.790] were significantly higher in GDM women with CHT than those without (all P 0.05). For pregnant women with normal pre-pregnancy BMI, HOMA-IR (3.0±1.5 vs 2.3±1.2, t=-2.217), fasting plasma glucose [(5.4±0.5) vs (5.1±0.5) mmol/L, t=-2.299] and the incidence of preeclampsia [2/14 vs 1.6% (26/1 576), χ2=6.545] were higher in the CHT group than the non-CHT group (all P 0.05). After adjusting for age, fasting plasma glucose, pre-pregnancy BMI and weight gain during pregnancy, the elevated HOMA-IR level increased the risk of preterm birth (OR=1.223, 95%CI: 1.093-1.369, P<0.001) in GDM women without CHT. Conclusions GDM gravida complicated by CHT have severe insulin resistance and a higher incidence of preeclampsia, but the risk of other pregnancy outcomes are not increased. Key words: Diabetes, gestational; Hypertension; Insulin resistance; Pregnancy outcome