title: Associations of β-cell function and insulin resistance with youth-onset type 2 diabetes and prediabetes among Asian Indians.
abstract: OBJECTIVE
  This study examined β-cell function and insulin resistance (homeostasis model assessment-insulin resistance [HOMA-IR]) in Asian Indian youth with type 2 diabetes mellitus (T2DM-Y) and prediabetes.
  
  
  METHODS
  Eighty-two subjects with non-insulin-requiring type 2 diabetes and age of onset below 25 years were recruited within 18 months of diagnosis and compared with age- and sex-matched subjects with prediabetes (n=31) and normal glucose tolerance (NGT) (n = 83). Body mass index (BMI) and waist circumference were measured, and blood samples were taken in the fasting state and after 30, 60, 90, and 120 min of an oral glucose load for assessment of plasma glucose and insulin levels. Insulin sensitivity/resistance measures was calculated by using the reciprocal of the fasting insulin, the HOMA-IR equation, and the composite whole body insulin sensitivity index (Matsuda Index), and β-cell function was calculated by the oral disposition index (DIo).
  
  
  RESULTS
  T2DM-Y and prediabetes subjects had higher BMI, waist circumference, and fasting insulin than NGT subjects (P<0.05 for each). The 30-min insulin levels were lower in T2DM-Y and higher in prediabetes subjects compared with NGT (57 and 140 vs. 129 μIU/mL, P<0.001). The T2DM-Y group had greater insulin resistance (HOMA-IR, 1.87 vs. 0.97; P<0.05) and lower β-cell function (DIo, 0.36 vs. 3.28; P<0.001) than NGT. In separate models, the Matsuda Index and DIo were independently associated with prediabetes and T2DM-Y (P<0.05). However, when both were included together, only DIo remained associated with T2DM-Y, whereas both DIo and Matsuda Index were associated with prediabetes (P<0.05). When controlled for adiposity (BMI and waist circumference), an association was observed but in opposite directions, with waist being positively associated with prediabetes (P = 0.016) and BMI negatively associated with T2DM-Y (P = 0.009).
  
  
  CONCLUSIONS
  Among Asian Indians, β-cell dysfunction appears to be more strongly associated with T2DM-Y than insulin resistance.
authors.affiliation: Madras Diabetes Research Foundation and Dr. Mohan's Diabetes Specialities Centre, WHO Collaborating Centre for Non-Communicable Diseases Prevention and Control and IDF Centre for Education, Gopalapuram, Chennai, India. drmohans@diabetes.ind.in
authors.forename: Viswanathan
authors.initials: V
authors.lastname: Mohan
authors.forename: Anandakumar
authors.initials: A
authors.lastname: Amutha
authors.forename: Harish
authors.initials: H
authors.lastname: Ranjani
authors.forename: Ranjit
authors.initials: R
authors.lastname: Unnikrishnan
authors.forename: Manjula
authors.initials: M
authors.lastname: Datta
authors.forename: Ranjit Mohan
authors.initials: RM
authors.lastname: Anjana
authors.forename: Lisa
authors.initials: L
authors.lastname: Staimez
authors.forename: Mohammed K
authors.initials: MK
authors.lastname: Ali
authors.forename: K M Venkat
authors.initials: KM
authors.lastname: Narayan
mesh_terms: D017668:Age of Onset; D001786:Blood Glucose / Q000378:metabolism*; D015992:Body Mass Index; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000453:epidemiology* / Q000208:ethnology; D005215:Fasting; D005260:Female; D005951:Glucose Tolerance Test; D006706:Homeostasis; D006801:Humans; D006943:Hyperglycemia / Q000097:blood / Q000453:epidemiology* / Q000208:ethnology / Q000378:metabolism*; D007194:India / Q000453:epidemiology; D007333:Insulin Resistance / Q000208:ethnology; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D008297:Male; D011236:Prediabetic State / Q000097:blood / Q000453:epidemiology* / Q000208:ethnology; D055105:Waist Circumference; D044465:White People; D055815:Young Adult
chemical_list: D001786:Blood Glucose