〔Abstract〕 Objective To explore the association between serum γ-aminobutyric acid(GABA) levels and the risk of developing type 2 diabetes(T2DM). Methods 187 cases of T2DM patients attending the hospital were selected as the T2DM group, and 187 cases of non-T2DM population attending the same period of time were selected as the control group according to age(±3 years) and gender 1 ∶1. On-site questionnaires and physical examination were conducted for the study subjects, and serum levels of GABA, Malondialdehyde(MDA) and activities of superoxide dismutase(SOD) and Glutathione peroxidase(GSH-Px) were detected by using ELISA kits. The differences in the levels of GABA and oxidative stress indicators(SOD, GSH-Px, MDA) between the two groups were compared, and the correlation between GABA and oxidative stress indicators was analyzed by Spearman′s method; GABA and oxidative stress indicators were divided into three groups according to their control quartiles, respectively [low level group(Q1:P75)], and conditional logistic regression was applied to analyze the relationship between GABA, oxidative stress indicators and the risk of developing T2DM; the dose-response relationship between GABA, oxidative stress indicators and the risk of developing T2DM was analyzed by using restricted cubic spline(RCS). Results Compared with the control group, GABA level and GSH-Px activity decreased and MDA level increased in the T2DM group(P<0.05). Spearman′s correlation analysis showed that GABA level was positively correlated with SOD and GSH-Px activities and negatively correlated with MDA level(P<0.001). Conditional logistic regression analysis showed that medium levels of SOD and GSH-Px as well as medium and high levels of GABA were protective factors for T2DM compared with low levels in each group(P<0.05). RCS results showed that a negative dose-response relationship between GABA, GSH-Px and the risk of developing T2DM, and SOD showed a trend of decreasing and then increasing the risk of developing T2DM(P<0.05). Conclusion Serum GABA levels have been associated with the risk of developing T2DM. As serum GABA levels increase, the risk of developing T2DM may decrease.