Reference Intervals And Cut-off Points Of 1,5-anhydroglucitol In Jiangsu Province

Objective:Serum 1,5-anhydroglucitol(1,5-AG)is a new glycemic marker which can reflect glucose fluctuation over 3-7 days,and is now increasingly used to monitor glucose control and to screen for diabetes.However 1,5-AG has not been extensively used in China because short of epidemiological support.Our study aimed to establish the reference intervals for a population with normal glucose tolerance in Jiangsu province and explore the determinants of these intervals.Also we established the cut-off point to screen for diabetes.Method:Participants:2239 participants from Jiangsu province were enrolled in the research in 2018,among whom participants with history of diabetes or usage of diabetic drugs,history of hypertension,liver/renal disease and abnormal blood lipid were excluded,leaving 1516 participants for cut-off point research.Oral glucose tolerance test(OGTT)was then conducted to exclude participants with abnormal blood glucose,leaving 646 for reference intervals.Clinical measurements:height,weight,waist and hip circumstance,blood pressure and heart rate were measured.Waist-to-height ratio,waist-to-hip ratio and body mass index were calculated.OGTT was conducted after 8-hour fasting,fast blood glucose(FPG)and 2-hour postprandial blood glucose were tested.Also,other biochemical index were measured including:blood lipid:high density lipoprotein(HDL),low density lipoprotein(LDL),total cholesterol(TC),triglyceride(TG);liver function:glutamic-pyruvic transaminase(ALT),glutamic-oxalacetic transaminase(AST);renal function:blood urea nitrogen(BUN),creatinine(Cr),uric acid(UA),glucose biomarker:glycated hemoglobin(HbAlc),1,5-anhydroglucitol(1,5-AG).Estimated glomerular filtration rate(eGFR)was calculated by Cockgroft-Gault formula.An questionnaire was collected from each participant concerning on age,smoking habit,family history of diabetes,and concomitant use of medication.Statistical analysis:The reference intervals were calculated using parametric method:RI=mean±2 × SD,confidence intervals(CI)=RI±2.81 × SD/√N.Cut-off point was calculated using ROC curve using WHO criteria as the golden standard.Youden index was calculated for the best cut-off point.SPSS Software(version 20,SPSS Inc,Chicago,IL,USA)was used for the statistical analyses.P<0.05 was considered statistically significant.Results:1.reference intervals:The average age of the participants was 50.5±9.0 years and 69.5%of them were females.The reference intervals were 15.8-52.6ug/mL for males and 14.3-48.0 ug/mL for females.Among females,the reference intervals were 13.9-45.3ug/mL and 14.6-49.6ug/mL for menopausal and post-menopausal females respectively.Males showed higher 1,5-AG concentrations than females,and post-menopausal females’ 1,5-AG level is higher than those who are menopausal.There was a positive correlation between uric acid and 1,5-AG in both genders.Positive correlation between 1,5-AG and age was only observed in females.2.cut-off point:101 participants were newly-diagnosed diabetes,the morbidity of diabetes was 6.7%.The average of 1,5-AG was 27.88±10.46ug/ml.There was no difference of 1,5-AG between genders.The 1,5-AG concentration of diabetic patients was significantly lower than non-diabetic participants.1,5AG had a negative correlation with FPG,2hPG and HbAlc in all participants and the correlations were much more obvious in diabetic patients.The best cut-off point for 1,5-AG to screen for diabetes was 23ug/ml with AUC 0.776,sensibility 72.28%,specificity 71.87%.When combining 1,5-AG with FPG,the AUC can be improved to 0.964,with sensibility 88.12%,specificity 71.87%.When 1,5-AG combined with HbAlc the AUC was 0.909,sensibility was 80.20%,specificity 66.92%.Conclusion:We established reference intervals for 1,5-AG in Jiangsu province,and the level of 1,5-AG is affected by sex,uric acid and age.The best cut-off point for 1,5-AG is 23 ug/mL.Combining 1,5-AG with fast blood glucose to screen for diabetes can avoid 72.4%population for OGTT.