Analysis of risk factors for adverse pregnancy outcomes in women with gestational diabetes mellitus

Abstract

Objective To evaluate clinical features,insulin sensitivity and β-cell function of pregnant women with different glucose tolerance status,so as to identify the possible risk factors for adverse pregnancy outcomes in women with gestational diabetes mellitus (GDM).Methods We retrospectively analyzed the clinical data of 360 pregnant women with positive results of 50 g glucose challenge test who received antenatal care and admitted for delivery in the period from January 2009 to June 2012 in Peking Union Medical College Hospital.According to the result of 100 g oral glucose tolerance test (OGTT),the 360 women were divided into GDM group (n =83),impaired glucose tolerance (IGT) group (n =75),and normal glucose tolerance (NGT) group (n =202).The blood glucose level in all those women was controlled in normal range for gestational period.We compared the general clinical data,biochemical indexes,insulin resistance index,insulin sensitivity index,function index of islet β-cell,first-and second-phase insulin secretion,insulin secretion-sensitivity index as well as the pregnancy outcomes of the 3 groups,analyzing the possible risk factors for adverse pregnancy outcomes in women with GDM.Results Compared with the NGT group,the pregnant women in GDM group were older [(33.1 ± 3.7) years vs.(31.7 ± 3.4) years,P =0.008],had higher systolic blood pressure [(115.8 ± 9.7) mmHg vs.(111.4 ± 13.5) mmHg (1 mmHg =0.133 kPa),P =0.031] and diastolic blood pressure in first trimester [(75.4 ±9.0) mmHg vs.(71.8 ±8.8) mmHg,P =0.010],higher positive rate of family history of diabetes in first-degree relatives (37.3％ vs.22.3％,P =0.012),positive rate of insulin therapy (10.8％ vs.0％,P =0.001),serum triglyceride level [(2.8 ±0.9) mmol/L vs.(2.3 ±0.9) mmol/L,P =0.001],free fatty acid level [(486.7 ± 137.6) μmol/L vs.(438.1 ± 140.7) μmol/L,P =0.033],and C-reactive protein level [(5.7 ± 4.3) mg/L vs.(3.6 ± 3.0) mg/L,P =0.001].The GDM group had a larger pre-pregnancy body mass index [(22.6 ± 2.9) kg/m2] than that in IGT group [(21.3 ± 2.7) kg/m2] (P =0.049) and NGT group [(21.2 ±2.8) kg/m2] (P =0.003).In the order from NGT to IGT to GDM group,the hemoglobin A1c [(5.2 ± 0.3) ％ vs.(5.3 ± 0.3) ％ vs.(5.4 ± 0.3) ％,P =0.001,P =0.007],the areas under curve of glucose [(20.4±2.0) mmol · h/L vs.(22.9 ± 1.5) mmol · h/L vs.(26.9 ±2.1) mmol · h/L,both P=0.001] and the areas under curve of insulin [(1.7 ±0.9) × 103 pmol · h/L vs.(2.1 ± 1.1) × 103 pmol · h/L vs.(2.7±1.3) ×103 pmol · h/L,P=0.001,P=0.007] increased gradually,while insulin sensitivity index (88.1 ± 52.1 vs.80.0 ± 30.6 vs.50.0 ± 24.1,P =0.001,P =0.014) and insulin secretion-sensitivity index (134 507.0 ± 43 291.0 vs.102 542.0 ± 15 291.0 vs.77 582.0 ± 20 764.0,both P =0.001) decreased gradually.The insulin resistance index in the GDM group (3.3 ± 2.2) was significantly higher than that in IGT (2.2 ± 1.0) and NGT groups (3.0 ± 1.1) (both P =0.001).The function of β-cell,first-and second-phase insulin secretion were not significantly different among the 3 groups.Compared with the NGT group,pregnant women with GDM had shorter gestational age [(38.8 ± 1.1) weeks vs.(39.4 ± 1.1) weeks,P=0.004] and higher incidence of adverse pregnancy outcomes (44.6％ vs.21.8％,P =0.001).Seven risk factors predicting adverse pregnancy outcomes in women with GDM were identified,including pre-pregnancy body mass index (P=0.017),0-,1-,and 2-hour blood glucose in 100 g OGTT (P=0.036,P=0.009,P=0.004),3-hour insulin (P =0.014),and hemoglobin A1 c (P =0.002) and C-reactive protein (P =0.005) in second trimester,among which 1-hour blood glucose displayed the highest coefficient (OR =2.767).Conclusions Pregnant women with GDM have elevated blood pressure,dyslipidemia and increased inflammatory cytokine C-reactive protein.Women with GDM and IGT both show insulin resistance and β-cell dysfunction,and these impairments are more severe in women with GDM.Higher pre-pregnancy body mass index and blood glucose levels during pregnancy are associated with adverse pregnancy outcomes in women with GDM. Key words: Gestational diabetes mellitus ; Insulin sensitivity ; Islet β-cell function ; Adverse pregnancy outcomes