Triglyceride and glucose index and the risk of gestational diabetes mellitus: A nationwide population-based cohort study

Aims Pre-pregnancy insulin resistance is one of the main pathophysiologies of gestational diabetes mellitus (GDM). Triglyceride-glucose (TyG) index is a marker of insulin resistance. We aimed to evaluate the association between pre-pregnancy TyG index and GDM in primipara women. Methods A total of 380,208 women who underwent a Korean national health screening exam within 2 years before their first delivery, between January 1, 2012 and December 31, 2015, were included. The TyG index was calculated as ln [triglyceride (mg/dL) × fasting plasma glucose (mg/dL)/2]. Results Among the 380,208 primipara women, 17,239 women were diagnosed with GDM (4.53%). Multivariate logistic regression analysis adjusted for risk factors showed a higher odds ratio of 1.73 for GDM (95% CI 1.65-1.81) in the highest quartile than that in the lowest quartile. A 1-SD increase in the TyG index increased the risk of GDM (31%) and GDM requiring insulin therapy (82%) in the fully adjusted model. A 1-unit increase in the TyG index significantly increased the risk of GDM and GDM requiring insulin treatment by 1.81 and 3.69 times, respectively.The impact of a high TyG index on the risk of GDM was more profound in the subjects aged ≥ 35 years, with obesity, with impaired fasting glucose, who are current smokers, and with a family history of diabetes mellitus. Conclusions Increased pre-pregnancy TyG index is associated with a risk of GDM. Elevation of the TyG index may be an early marker of GDM.