title: Role of various indices derived from an oral glucose tolerance test in the prediction of conversion from prediabetes to type 2 diabetes.
abstract: OBJECTIVE
  The clinical implications of prediabetes for development of type 2 diabetes may differ for Asian ethnicity. We investigated various indices derived from a 2-h oral glucose tolerance test (OGTT) in people with prediabetes to predict their future risk of diabetes.
  
  
  METHODS
  We recruited 406 consecutive subjects with prediabetes from 2005 to 2006 and followed them up every 3-6 months for up to 9 years. Prediabetes was defined as isolated impaired fasting glucose (IFG), isolated impaired glucose tolerance (IGT), combined glucose intolerance (CGI), or isolated elevated HbA1c (5.7-6.4%, 39-46 mmol/mol) without IFG or IGT. The rate of diabetes conversion was compared between prediabetes categories. The association of glycemic indices with development of diabetes was also investigated.
  
  
  RESULTS
  Eighty-one patients were diagnosed with diabetes during the 9-year follow-up (median 46.0 months). The rate of diabetes conversion was higher in subjects with CGI (31.9%), or isolated IGT (18.5%) than in those with isolated IFG (15.2%) or isolated elevated HbA1c (10.9%). Surrogate markers reflecting β-cell dysfunction were more closely associated with diabetes conversion than insulin resistance indices. Subjects with a 30-min postload glucose ≥ 165 mg/dL and a 30-min C-peptide < 5 ng/mL had 8.83 times greater risk (95% confidence interval 2.98-26.16) of developing diabetes than other prediabetic subjects.
  
  
  CONCLUSIONS
  In Asians, at least Koreans, β-cell dysfunction seems to be the major determinant for diabetes conversion. A combination of high glucose and low C-peptide levels at 30 min after OGTT may be a good predictor for diabetes conversion in this population.
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea.
authors.forename: Ye An
authors.initials: YA
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea; Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea.
authors.forename: Eu Jeong
authors.initials: EJ
authors.lastname: Ku
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea; Department of Internal Medicine, Kyungpook National University College of Medicine and Kyungpook National University Chilgok Hospital, Daegu, South Korea.
authors.forename: Ah Reum
authors.initials: AR
authors.lastname: Khang
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea; Department of Internal Medicine, Konkuk University College of Medicine and Konkuk University Chungju Hospital, Chungju, South Korea.
authors.forename: Eun Shil
authors.initials: ES
authors.lastname: Hong
authors.affiliation: Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea.
authors.forename: Kyoung Min
authors.initials: KM
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea.
authors.forename: Jae Hoon
authors.initials: JH
authors.lastname: Moon
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea; Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea.
authors.forename: Sung Hee
authors.initials: SH
authors.lastname: Choi
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea.
authors.forename: Kyong Soo
authors.initials: KS
authors.lastname: Park
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea; Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea.
authors.forename: Hak Chul
authors.initials: HC
authors.lastname: Jang
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea; Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea. Electronic address: limsoo@snu.ac.kr.
authors.forename: Soo
authors.initials: S
authors.lastname: Lim
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000032:analysis* / Q000378:metabolism; D002096:C-Peptide / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D018149:Glucose Intolerance / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology; D005951:Glucose Tolerance Test; D006305:Health Status Indicators; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D008875:Middle Aged; D011236:Prediabetic State / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology*; D012306:Risk
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin
keywords: Insulin resistance; Oral glucose tolerance test; Prediabetes; Type 2 diabetes; β-Cell function