title: Predictive value of HbA1c for incident diabetes among subjects with impaired glucose tolerance--analysis of the Indian Diabetes Prevention Programmes.
abstract: OBJECTIVE
  The objectives of the study were to assess the predictive value of baseline HbA(1c) for incident diabetes among the participants with impaired glucose tolerance in the Indian Diabetes Prevention Programmes 1 and 2.
  
  
  METHODS
  Data at baseline and at 3-year follow-up were analysed in combined cohorts of the Indian Diabetes Prevention Programmes 1 and 2. Within the 3 years, 324 of the 845 participants developed diabetes (World Health Organization criteria). The predictive value of baseline HbA(1c) for incident diabetes was determined by logistic regression analysis.
  
  
  RESULTS
  Baseline HbA(1c) values had heterogenous distribution. The distribution was similar in isolated impaired glucose tolerance or in impaired glucose tolerance in combination with impaired fasting glucose. A progressive increase in diabetes occurred with increasing HbA(1c). HbA(1c) showed the strongest association with incident diabetes in the multiple logistic regression analysis (odds ratio 3.548, P < 0.0001). The cut-off HbA(1c) of 43 mmol/mol (6.05%) had 67% sensitivity and 60% specificity to predict future diabetes. The diagnostic sensitivity of HbA(1c) of ≥ 48 mmol/mol (≥ 6.5%) was only 51%, with a specificity of 87%, when compared with the oral glucose tolerance glucose values.
  
  
  CONCLUSIONS
  Baseline HbA(1c) was highly predictive of future diabetes in Asian Indian subjects with impaired glucose tolerance and nearly 60% of the incidence occurred with values ≥ 42 mmol/mol (≥ 6.0). Diagnostic sensitivity of HbA(1c) ≥ 48 mmol/mol (≥ 6.5%) for new diabetes was only 51% using the oral glucose tolerance test as the standard for comparison.
authors.affiliation: India Diabetes Research Foundation and Dr A. Ramachandran's Diabetes Hospitals, Chennai, India. ramachandran@vsnl.com
authors.forename: A
authors.initials: A
authors.lastname: Ramachandran
authors.forename: C
authors.initials: C
authors.lastname: Snehalatha
authors.forename: A
authors.initials: A
authors.lastname: Samith Shetty
authors.forename: A
authors.initials: A
authors.lastname: Nanditha
mesh_terms: D001786:Blood Glucose / Q000378:metabolism; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis* / Q000453:epidemiology / Q000517:prevention & control; D005215:Fasting; D005260:Female; D018149:Glucose Intolerance / Q000175:diagnosis* / Q000453:epidemiology / Q000517:prevention & control; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D015994:Incidence; D007194:India; D016015:Logistic Models; D008297:Male; D008687:Metformin / Q000627:therapeutic use*; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012307:Risk Factors; D040242:Risk Reduction Behavior; D044465:White People
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; D008687:Metformin