title: A1C cut points to define various glucose intolerance groups in Asian Indians.
abstract: OBJECTIVE To determine A1C cut points for glucose intolerance in Asian Indians. RESEARCH DESIGN AND METHODS A total of 2,188 participants without known diabetes were randomly selected from the Chennai Urban Rural Epidemiology Study. All had fasting plasma glucose (FPG) and 2-h postload plasma glucose measurements after a 75-g load and were classified as having impaired fasting glucose (IFG) (American Diabetes Association [ADA] criteria, FPG > or =5.5 and <7 mmol/l, and World Health Organization [WHO] criteria, FPG > or =6.1 and <7 mmol/l), impaired glucose tolerance (IGT) (2-h postload plasma glucose > or =7.8 and <11.1 mmol/l), or diabetes (FPG > or =7 mmol/l and/or 2-h postload plasma glucose > or =11.1 mmol/l). A1C was measured using the Bio-Rad Variant machine. Based on receiver operating characteristic curves, optimum sensitivity and specificity were derived for defining A1C cut points for diabetes, IGT, and IFG. RESULTS Mean +/- SD values of A1C among subjects with normal glucose tolerance, IGT, and diabetes were 5.5 +/- 0.4, 5.9 +/- 0.6, and 8.3 +/- 2.0%, respectively (P(trend) < 0.001) with considerable overlap. To identify diabetes based on 2-h postload plasma glucose, the A1C cut point of 6.1% had an area under the curve (AUC) of 0.941 with 88.0% sensitivity and 87.9% specificity. When diabetes was defined as FPG > or =7.0 mmol/l, the A1C cut point was 6.4% (AUC = 0.966, sensitivity 93.3%, and specificity 92.3%). For IGT, AUC = 0.708; for IFG, AUC = 0.632 (WHO criteria) and 0.708 (ADA criteria), and the A1C cut point was 5.6%. CONCLUSIONS In Asian Indians, A1C cut points of 6.1 and 6.4% defined diabetes by 2-h postload plasma glucose or FPG criteria, respectively. A value of 5.6% optimally identified IGT or IFG but was <70% accurate.
authors.affiliation: Madras Diabetes Research Foundation and Dr. Mohan's Diabetes Specialities Centre, World Health Organization Collaborating Centre for Non-Communicable Diseases Prevention and Control, and International Diabetes Federation Centre for Education, Chennai, India. drmohans@vsnl.net
authors.forename: Viswanathan
authors.initials: V
authors.lastname: Mohan
authors.forename: Venkataraman
authors.initials: V
authors.lastname: Vijayachandrika
authors.forename: Kuppan
authors.initials: K
authors.lastname: Gokulakrishnan
authors.forename: Ranjit Mohan
authors.initials: RM
authors.lastname: Anjana
authors.forename: Anbazhagan
authors.initials: A
authors.lastname: Ganesan
authors.forename: Mary Beth
authors.initials: MB
authors.lastname: Weber
authors.forename: K M Venkat
authors.initials: KM
authors.lastname: Narayan
mesh_terms: D000328:Adult; D000465:Algorithms; D019540:Area Under Curve; D044466:Asian People / Q000706:statistics & numerical data; D001786:Blood Glucose / Q000032:analysis; D003430:Cross-Sectional Studies; D003940:Diagnostic Techniques, Endocrine / Q000592:standards*; D018149:Glucose Intolerance / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology; D006442:Glycated Hemoglobin / Q000032:analysis* / Q000592:standards; D006801:Humans; D007194:India / Q000453:epidemiology; D008875:Middle Aged; D011153:Population; D015995:Prevalence; D012016:Reference Values; D012680:Sensitivity and Specificity
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human