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Background & aims: To date, the prevalence of Gestational diabetes mellitus (GDM) in China was 17.5%. Given the substantial relevance of GDM for medium-and long-term health of both mother and offspring and the paucity of existing data on the link between maternal diet and glucose homeostasis during pregnancy in Asian population, additional studies are needed. To examine the relevance of dietary glycemic index (GI), glycemic load (GL) and fiber intake before and during pregnancy for the development of GDM and glucose homeostasis over the course of pregnancy. Methods: Cox proportional hazards analysis and linear mixed effects regressions were performed on data from 9317 women for whom three food frequency questionnaires (pre-pregnancy, 1 st and 2 nd trimesters) and biochemical measures during pregnancy were available. Investigated outcome variables included GDM risk, fasting plasma glucose (FPG), glycated hemoglobin (HbA 1C ), and homeostasis model assessment insulin resistance (HOMA-IR) in the 1st, 2nd and 3rd trimesters. Results: Women in the highest tertile of dietary GI (or GL) before pregnancy, in the 1 st , or the 2 nd trimester respectively had a 12% (15%), 25% (23%) or 29% (25%) higher risk of developing GDM than those in the lowest tertile (all p for trend 0.02). Women with the highest dietary fiber intake before pregnancy, in the 1st or 2nd trimester had a 11%, 17% or 18% lower GDM risk (all p for trend 0.03). Moreover, increases in GI or GL and decreases in fiber intake over the course of pregnancy (1 st to 3 rd trimesters) were independently associated with adverse concurrent developments in FPG, HbA 1C and HOMA-IR (p 0.03). Conclusions: Our study indicates that dietary GI, GL and fiber intake before and during pregnancy affects glucose homeostasis of pregnant Chinese women.

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Purpose Studies regarding the association between dietary fat intake and gestational diabetes mellitus (GDM) are limited and provide conflicting findings. Thus, the study aims to examine the association of dietary fat intake in the year preceding pregnancy and during pregnancy with the risk of GDM, taking the relevance of dietary protein intake on GDM into consideration. Methods A prospective study was conducted in 6299 singleton pregnancies, using the data from the Nutrition in Pregnancy and Growth in Southwest China (NPGSC). A validated food frequency questionnaire was used to assess dietary fat intake in the year preceding pregnancy and during the first and second trimesters of pregnancy. Logistic regression analysis was used to assess the prospective associations of dietary fat intake and the type and source of dietary fats in different time windows with GDM risk. Results Higher intake of total fat [OR (95% CI): 2.21 (1.19–4.20), P = 0.02] during 12–22 weeks of gestation was associated with higher GDM risk. However, adjustment for animal protein intake greatly attenuated this association [OR (95% CI): 1.81 (0.93, 3.64), P = 0.11]. Total fat intake neither in the year preceding pregnancy nor during the early pregnancy was associated with GDM risk. Moreover, insignificant associations were observed between intakes of vegetable fat, animal fat, cholesterol, saturated fatty acid, monounsaturated fatty acid and polyunsaturated fatty acid one year before pregnancy and during the first and second trimesters and GDM risk. Conclusion Our study indicated that dietary fat intake one year before pregnancy and across the two pregnancy trimesters preceding the diagnosis of GDM has no relevance on GDM risk among Chinese women, particularly those with normal BMI, low, or normal calorie intake.