title: Glucose patterns during the OGTT and risk of future diabetes in an urban Indian population: The CARRS study.
abstract: OBJECTIVE
  Traditionally, fasting and 2-hour post challenge plasma glucose have been used to diagnose diabetes. However, evidence indicates that clinically relevant pathophysiological information can be obtained by adding intermediate time-points to a standard oral glucose tolerance test (OGTT).
  
  
  METHODS
  We studied a population-based sample of 3666 Asian Indians without diabetes from the CARRS-Chennai Study, India. Participants underwent a three-point (fasting, 30-min, and 2-h) OGTT at baseline. Patterns of glycemic response during OGTT were identified using latent class mixed-effects models. After a median follow-up of two years, participants had a second OGTT. Logistic regression adjusted for diabetes risk factors was used to compare risk of incident diabetes among participants in different latent classes.
  
  
  RESULTS
  We identified four latent classes with different glucose patterns (Classes 1-4). Glucose values for Classes 1, 2, and 4 ranked consistently at all three time-points, but at gradually higher levels. However, Class 3 represented a distinct pattern, characterized by high 30-min (30minPG), normal fasting (FPG) and 2-h (2hPG) plasma glucose, moderately high insulin sensitivity, and low acute insulin response. Approximately 22% of participants were categorized as Class 3, and had a 10-fold risk of diabetes compared to the group with the most favorable glucose response, despite 92.5% of Class 3 participants having normal glucose tolerance (NGT) at baseline.
  
  
  CONCLUSIONS
  Elevated 30minPG is associated with high risk of incident diabetes, even in individuals classified as NGT by a traditional OGTT. Assessing 30minPG may identify a subgroup of high-risk individuals who remained unidentified by traditional measures.
authors.affiliation: Department of Public Health, Aarhus University, Bartholins Allé 2, Building 1260, DK-8000, Aarhus C, Denmark; Danish Diabetes Academy, Odense University Hospital, Sdr Boulevard 29, DK-5000 Odense C, Denmark; Department of Medical Physics and Informatics, University of Szeged, Korányi fasor 9, H-6720 Szeged, Szeged, Hungary. Electronic address: adam.hulman@ph.au.dk.
authors.forename: Adam
authors.initials: A
authors.lastname: Hulman
authors.affiliation: Emory Global Diabetes Research Center, Hubert Department of Global Health, Rollins School of Public Health, 1518 Clifton Road NE. Room 7040 N Emory University, Atlanta, GA, USA. Electronic address: ugujral@emory.edu.
authors.forename: Unjali P
authors.initials: UP
authors.lastname: Gujral
authors.affiliation: Nutrition and Health Sciences Program, Emory University, 1518 Clifton Road, Room 7000, Atlanta, GA, USA; Department of Medicine, School of Medicine, 201 Dowman Drive Emory University, Atlanta, GA, USA. Electronic address: knaraya@emory.edu.
authors.forename: K M Venkat
authors.initials: KMV
authors.lastname: Narayan
authors.affiliation: Madras Diabetes Research Foundation & Dr. Mohan's Diabetes Specialties Centre, WHO Collaborating Centre for Non-communicable Diseases, Prevention & Control, IDF Centre of Education, Chennai, India. Electronic address: guhapradeepa@gmail.com.
authors.forename: Rajendra
authors.initials: R
authors.lastname: Pradeepa
authors.affiliation: Madras Diabetes Research Foundation & Dr. Mohan's Diabetes Specialties Centre, WHO Collaborating Centre for Non-communicable Diseases, Prevention & Control, IDF Centre of Education, Chennai, India. Electronic address: deepa.mohan1@gmail.com.
authors.forename: Deepa
authors.initials: D
authors.lastname: Mohan
authors.affiliation: Madras Diabetes Research Foundation & Dr. Mohan's Diabetes Specialties Centre, WHO Collaborating Centre for Non-communicable Diseases, Prevention & Control, IDF Centre of Education, Chennai, India. Electronic address: dranjana@drmohans.com.
authors.forename: Ranjit Mohan
authors.initials: RM
authors.lastname: Anjana
authors.affiliation: Madras Diabetes Research Foundation & Dr. Mohan's Diabetes Specialties Centre, WHO Collaborating Centre for Non-communicable Diseases, Prevention & Control, IDF Centre of Education, Chennai, India. Electronic address: drmohans@diabetes.ind.in.
authors.forename: Viswanathan
authors.initials: V
authors.lastname: Mohan
authors.affiliation: Steno Diabetes Center Copenhagen, Niels Steensens Vej 2, DK-2820, Gentofte, Denmark. Electronic address: kristine.faerch@regionh.dk.
authors.forename: Kristine
authors.initials: K
authors.lastname: Færch
authors.affiliation: Department of Public Health, Aarhus University, Bartholins Allé 2, Building 1260, DK-8000, Aarhus C, Denmark; Danish Diabetes Academy, Odense University Hospital, Sdr Boulevard 29, DK-5000 Odense C, Denmark. Electronic address: daniel.witte@ph.au.dk.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Witte
mesh_terms: D000328:Adult; D044466:Asian People; D001786:Blood Glucose / Q000032:analysis / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000175:diagnosis* / Q000453:epidemiology; D005215:Fasting / Q000097:blood; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007194:India / Q000453:epidemiology; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D011236:Prediabetic State / Q000097:blood* / Q000453:epidemiology; D011379:Prognosis; D012307:Risk Factors; D014505:Urban Population
chemical_list: D001786:Blood Glucose; D007328:Insulin
keywords: Asian Indian; Diabetes physiology; Oral glucose tolerance test; Type 2 diabetes