title: Evidence of reduced β-cell function in Asian Indians with mild dysglycemia.
abstract: OBJECTIVE
  To examine β-cell function across a spectrum of glycemia among Asian Indians, a population experiencing type 2 diabetes development at young ages despite low BMI.
  
  
  METHODS
  One-thousand two-hundred sixty-four individuals without known diabetes in the Diabetes Community Lifestyle Improvement Program in Chennai, India, had a 75-g oral glucose tolerance test, with glucose and insulin measured at 0, 30, and 120 min. Type 2 diabetes, isolated impaired fasting glucose (iIFG), isolated impaired glucose tolerance (iIGT), combined impaired fasting glucose and impaired glucose tolerance, and normal glucose tolerance (NGT) were defined by American Diabetes Association guidelines. Measures included insulin resistance and sensitivity (homeostasis model assessment of insulin resistance [HOMA-IR], modified Matsuda Index, 1/fasting insulin) and β-cell function (oral disposition index = [Δ insulin0-30/Δ glucose 0-30] × [1/fasting insulin]).
  
  
  RESULTS
  Mean age was 44.2 years (SD, 9.3) and BMI 27.4 kg/m(2) (SD, 3.8); 341 individuals had NGT, 672 had iIFG, IGT, or IFG plus IGT, and 251 had diabetes. Patterns of insulin resistance or sensitivity were similar across glycemic categories. With mild dysglycemia, the absolute differences in age- and sex-adjusted oral disposition index (NGT vs. iIFG, 38%; NGT vs. iIGT, 32%) were greater than the differences in HOMA-IR (NGT vs. iIFG, 25%; NGT vs. iIGT, 23%; each P < 0.0001). Compared with NGT and adjusted for age, sex, BMI, waist circumference, and family history, the odds of mild dysglycemia were more significant per SD of oral disposition index (iIFG: odds ratio [OR], 0.36; 95% CI, 0.23-0.55; iIGT: OR, 0.37; 95% CI, 0.24-0.56) than per SD of HOMA-IR (iIFG: OR, 1.69; 95% CI, 1.23-2.33; iIGT: OR, 1.53; 95% CI, 1.11-2.11).
  
  
  CONCLUSIONS
  Asian Indians with mild dysglycemia have reduced β-cell function, regardless of age, adiposity, insulin sensitivity, or family history. Strategies in diabetes prevention should minimize loss of β-cell function.
authors.affiliation: Nutrition and Health Sciences Program, Graduate Division of Biomedical and Biological Sciences, Laney Graduate School, Emory University, Atlanta, Georgia, USA. lisa.staimez@emory.edu
authors.forename: Lisa R
authors.initials: LR
authors.lastname: Staimez
authors.forename: Mary Beth
authors.initials: MB
authors.lastname: Weber
authors.forename: Harish
authors.initials: H
authors.lastname: Ranjani
authors.forename: Mohammed K
authors.initials: MK
authors.lastname: Ali
authors.forename: Justin B
authors.initials: JB
authors.lastname: Echouffo-Tcheugui
authors.forename: Lawrence S
authors.initials: LS
authors.lastname: Phillips
authors.forename: Viswanathan
authors.initials: V
authors.lastname: Mohan
authors.forename: K M Venkat
authors.initials: KM
authors.lastname: Narayan
mesh_terms: D050154:Adiposity / Q000502:physiology; D000328:Adult; D044466:Asian People; D001786:Blood Glucose / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000503:physiopathology; D005260:Female; D018149:Glucose Intolerance / Q000097:blood / Q000503:physiopathology; D005951:Glucose Tolerance Test; D006801:Humans; D007194:India; D050417:Insulin-Secreting Cells / Q000502:physiology*; D008297:Male
chemical_list: D001786:Blood Glucose