Study on the risk values of glycated hemoglobin in diabetes mellitus and pre-diabetes

Abstract

Objective To study the risk values of glycosylated hemoglobin (HbA1c) screening patients with diabetes mellitus(DM) and pre-diabetes(PreD) in different age and sex. Methods HbA1c results from10 840 in Taizhou Hospital in 2012 were retrospectively collected, and CHAID analysis of decision tree was used in preliminary hierarchy. Age was further divided into five groups according to the preliminary results, then one-way ANOVA and linear regression were utilized to determine the differences between age groups and the prediction intervals(PI) of HbA1c,respectively. The upper limit value of 95%PI of HbA1c was set as diabetes risk values(DRVs).By comparison of the sensitivity of DM patients screening by DRVs in 1 889 cases whose HbA1c were between 6.0% to 6.5% and the upper limit value of traditional HbA1c reference intervals to verify the screening value ofDRVs. Then the DRVs of HbA1c were utilized to screen DM in the population whose HbA1c is were 6.0%-6.5% in 2008,and followed their re-examination records toverify the screening value of the DRVs toin PreD patients. Results (1)On the basis of the initially root of decisiontree by age,the populationwas divided into 9 groups (P= 0.000, F= 231.462). By calculatingthe 95% confidence interval(CI) of each group and merging reasonably,it was finally divided into 5 groups: 20-30years,31-40years,41-50years,51-60years and >60years (F= 434.342, P= 0.000). (2)Using the method of linear regression, the 95% PI of HbA1c of the 5 groups showed as following: 20-30 years, males 4.6%-5.9%, females 4.6%-5.9%. 31-40 years, males 4.8%-6.0%, females 4.7%-6.0%. 41-50 years, males 4.9%-6.2%, females 4.8%-6.1%. 51-60 years, males 5.0%-6.3%, females 4.9%-6.2%.>60 years, males 5.1%-6.4%, females 5.0%-6.3%.The traditional HbA1c reference interval was4.8%-6.3%.(3)The screening sensitivity of DM by the upper limit value of traditional HbA1c reference interval and DRVs in group which HbA1c was between 6.0%-6.5% were 34.5% and 48.1%,respectively.(4)Reviewing of the group with HbA1c between 6.0%-6.5% and not diagnosed as DM in 2008, 49 hadnegative DM screening results by using the upper limit value of traditional HbA1c reference interval but were positive in our setting DRVs, and 13 have developed to DM now, which accounted for 26.5%. Conclusion HbA1c DRVs need to be set hierarchically between different age and sex groups as a supplement to the traditional reference interval，which has a great significance for the diagnosis and treatment of DM and also forthe screening and intervention of PreD patients. （Chin J Lab Med,2014,37:701-704） Key words: Hemoglobin A, glycosylated; Prediabetic state; Diabetes, mellitus; Confidence intervals; Reference values; Decision trees