title: Importance of standardization of hemoglobin A1c in the analysis of factors that predict hemoglobin A1c levels in non-diabetic residents of three distinct areas of Japan.
abstract: We performed a statistical analysis to elucidate effects of standardized measurement of hemoglobin A1c (HbA1c) on analysis of factors that affect HbA1c values. Subjects were participants in the Japan Public Health Center-based Prospective Study on Cancer and Cardiovascular Diseases, and a total of 1789 men and 3150 women in three distinct areas who did not have overt diabetes (HbA1c> or =6.1% or prior diagnosis) were analyzed. A different method of HbA1c assay was used in each area: high-performance liquid chromatography in one area and a different immunochemical method in each of the other two areas. Then, calibration of HbA1c was performed using two HbA1c standards (5.5 and 10.5%) provided by the Japan Diabetes Society. Analysis of co-variance was performed separately in men and women. When raw HbA1c data were used as the outcome, 'area', which represents differences in assay systems, lifestyles, etc. had a significant effect on HbA1c levels. When calibrated HbA1c data were used, however, 'area' was no longer a significant factor. In the latter analysis, age and BMI were the principal contributors to HbA1c, and parental history of diabetes had a weak effect in women. Thus, standardization of HbA1c reduced the difference between assay systems, and uncovered two common factors to determine HbA1c levels.
authors.affiliation: Department of Metabolic Diseases, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8655, Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Takahashi
authors.forename: M
authors.initials: M
authors.lastname: Noda
authors.forename: S
authors.initials: S
authors.lastname: Tsugane
authors.forename: S
authors.initials: S
authors.lastname: Kimura
authors.forename: Y
authors.initials: Y
authors.lastname: Akanuma
authors.forename: T
authors.initials: T
authors.lastname: Kuzuya
authors.forename: Y
authors.initials: Y
authors.lastname: Ohashi
authors.forename: T
authors.initials: T
authors.lastname: Kadowaki
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000704:Analysis of Variance; D044466:Asian People; D015992:Body Mass Index; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003920:Diabetes Mellitus / Q000235:genetics; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007564:Japan; D008297:Male; D008875:Middle Aged; D009679:Nuclear Family; D012016:Reference Values; D012727:Sex Characteristics
chemical_list: D006442:Glycated Hemoglobin