[Association between dietary glycemic load during first trimester and the risk of gestational diabetes mellitus: a...

Objective: To explore the effects of dietary glycemic load (GL) during first trimester on the risk of gestational diabetes mellitus (GDM). Methods: A prospective study was conducted among healthy women with singleton pregnancy at 8-14 weeks of gestation in a maternity out-patient clinic of maternal-and-child health care institution in Chengdu, Sichuan province. Information on dietary intake during the first trimester was collected through a 3-day 24-hour dietary recall. Glycemic index (GI) values were obtained from China Food Composition Tables (Standard Edition) and International Tables of Glycemic Index and Glycemic Load Values (2008). Dietary GL and GLs of staple foods were calculated based on GI values and the amount of carbohydrate consumed per day. Diagnostic criteria of GDM was followed the Guidelines for Diagnosis and Treatment of Pregnancy Diabetes in China (2014), and used on participants who underwent an oral glucose tolerant test during 24-28 weeks of gestation. Log-binomial regression models were used to explore the associations between both quartiles of dietary GL, GLs of staple foods and the risks of GDM,respectively. Results: The medians of dietary GL and GL of staple foods were 145.70 (113.23-180.85) and 121.05 (89.08-155.70), respectively. The median GL of both rice and tubers were 73.14 (43.89-107.50) and 3.43 (0.00-9.84), respectively. After adjusting for the age at pregnancy, pre-pregnancy body mass index and other confounding factors, results of log-binomial regressions analysis showed that when compared with the lowest quartile of dietary GL group, the third and highest quartiles of dietary GL groups increased the risk of GDM (RR=1.47, 95%CI: 1.20-1.80; RR=1.31, 95%CI: 1.04-1.64), respectively. Compared with the lowest quartile of GL of staple foods, the third and highest quartiles of GL of staple foods groups also increased the risk of GDM (RR=1.28, 95%CI: 1.04-1.58; RR=1.27, 95%CI: 1.02-1.60), respectively. The third and highest quartiles of GL of rice groups increased the risk of GDM (RR=1.30, 95%CI: 1.06-1.59; RR=1.28, 95%CI: 1.03-1.59), respectively, than the lowest quartile of GL of rice group. When compared with the lowest quartile of GL of tubers group, the highest quartile of GL of tubers group increased the risk of GDM (RR=1.30, 95%CI: 1.09-1.54). However, we did not notice the effects of wheat GL and coarse grain GL on the risk of GDM. Conclusions: A positive association was found between dietary glycemic load and the risk of GDM. Higher dietary glycemic load, especially in rice and tubers during first trimester, seemed to have increased the risk of GDM.