摘要Background:impaired glucose tolerance(IGT)is the early stage of diabetes and it would be deteriorated to type 2 diabetes mellitus(T2DM)easily if no intervention provided.In western medicine,drug ther-apy assisted with the intervention of lifestyle is predominated.However,drug therapy brings serious side effect and high prices,while lifestyle intervention is difficult to be insisted on by patients.Therefore,a green and effective intervention mode is urgently needed.Transcutaneous auricular vagus nerve stimu-lation(taVNS)is a noninvasive and green therapeutic method based on the theory of traditional Chinese medicine(TCM),which can regulate glucose metabolism and reduce blood glucose,but the clinical effect of it has not been clarified yet at present.Hence,this randomized controlled trial(RCT)aims at exploring the effectiveness and safety of taVNS in the treatment of IGT.Methods:a total of 158 patients with IGT will be randomized into a taVNS group and a transcutaneous non-auricular vagus nerve stimulation(tnVNS)group,79 cases in each one.In the taVNS group and the tnVNS group,electric stimulation would be applied to Yídǎn(胰胆 pancreas and gallbladder,CO11)and Pǐ(脾spleen,CO13)on auricular concha and Jiān(肩shoulder SF4.5)on auricular rim respectively.The electric stimulation parameters would be the same in the patients of two groups,for 30 min in each treatment,twice a day,6 weeks as one course and 2 courses of treatment required totally.In week 0,6 and 12 of intervention,the effectiveness indicators would be determined,i.e.fasting plasma glucose(FPG),2 h plasma glucose(2hPG)and glycosylated hemoglobin(HbA1c)successively.On week 0 and 12,body mass index(BMI)would be calculated,respiration,pulse and blood pressure would be recorded separately.Discussion:through observing the regulatory effect of taVNS on FPG,2hPG,HbA1c and BMI as well as the adverse reactions,the effectiveness and safety of taVNS in treatment of IGT would be evaluated.This study will provide a safe,effective,convenient and nontoxic side effect intervention for clinical treatment of IGT and prevention from the occurrence and development of T2DM.Trial registration:This trial has been registered on http://register.clinicaltrials.gov.Clinical Registra-tion Number:ClinicalTrials.gov NCT03343262.