Nested case-control study on the trend of blood lipid change during pregnancy and risk factors of gestational diabetes mellitus

Objective To explore the trend of blood lipid change during pregnancy and to analyze the risk factors of the gestational diabetes mellitus(GDM). Methods Based on the principle of nested case-control study,382 GDM patients with complete clinical records were selected as the case group from the reserch cohort,then they were divided into two groups after diet control: group A1(56 patients treated with insulin) and group A2(treated without insulin). Meanwhile,we selected 382 pregnant women with normal glucose tolerance test as the control group with the age of the GDM patients as the matching factor. Pregnant women's general information,blood lipid at various periods and other clinical data were collected. Chi-square test,two sample T-test,ANOVA Of repeated measure and logstic regression were used for statitical analysis. Results (1)Indicators of blood lipid level increased with gestational week in both 2 groups. The level of the low density lipoprotein(LDL) in the GDM group was higher than that in the control group in early and second trimester of pregnancy(P< 0. 05). However,the level of the LDL was similar in 2 groups in the third trimester of pregnancy.Meanwhile,the level of the high density lipoprotein(HDL) in GDM group was lower than that in normal group during the whole pregnancy(P< 0. 05).(2)The results of the logistic regression analysis showed that HDL over 1. 6 mmol/L was protective factor of GDM(OR = 0. 533,OR 95% CI: 0. 334-0. 849,P = 0. 008). Body weight gain before 24^th week being over 10 kg(OR = 1. 575,OR 95% CI: 1. 060-2. 340,P = 0. 024),fasting plasma glucose before 13 thweek being over 5. 1 mmol/L(OR = 2. 380,95% CI: 1. 657-3. 419,P = 0. 001),having history of GDM(OR = 2. 949,95% CI: 1. 179-7. 373,P = 0. 021),and LDL before 13^th week being over2. 5 mmol/L(OR = 2. 544,95% CI: 1. 470-4. 401,P = 0. 001) were risk factors of the GDM,but with history of GDM was the most important among these risk factors. Conclusion (1) Indicators of blood lipid level increased with gestational week. Higher level of HDL might be protective factor of GDM.(2) Pregnant women who has history of GDM,whose LDL before 13^th week being over 2. 5 mmol/L,or whose fasting plasma glucose before 13^th week being over 5. 1 mmol/L should be closely monitored. Meanwhile,pregnant women should be recommended to keep body weight gain below 10 kg before 24^th week in order to decrease the probability of developing GDM in secondary and third trimesters of pregnancy.