title: Type 2 diabetes in youth: are there racial differences in β-cell responsiveness relative to insulin sensitivity?
abstract: OBJECTIVE
  Non-diabetic African American (AA) youth have an upregulated insulin secretion relative to insulin sensitivity (IS) compared with their American White (AW) peers. We investigated if similar racial differences exist in youth with T2DM.
  
  
  METHODS
  Fourteen AAs and 14 AWs T2DM adolescents underwent evaluation of IS and clearance (hyperinsulinemic-euglycemic clamp), first- and second-phase insulin and C-peptide secretion (hyperglycemic clamp); body composition (DEXA); and abdominal adiposity (CT).
  
  
  RESULTS
  AA and AW T2DM had similar HbA1c, diabetes duration, BMI, and % body fat, with lower visceral fat in AAs (p = 0.013). While insulin-stimulated glucose disposal was similar in AA and AW (7.5 ± 1.0 vs. 7.3 ± 0.9 mg/kg FFM/min), IS tended to be lower (2.5 ± 0.4 vs. 3.8 ± 0.6 mg/kg FFM/min per µU/mL, p = 0.081). First-phase insulin (175.7 ± 52.9 vs. 66.6 ± 10.8 µU/mL, p = 0.01) and second-phase insulin (236.2 ± 40.7 vs. 105.1 ± 17.9 µU/mL, p = 0.008), and first-phase C-peptide (8.2 ± 1.2 vs. 5.0 ± 0.3 ng/mL, p = 0.02) and second-phase C-peptide (10.8 ± 0.9 vs. 7.6 ± 0.6 ng/mL, p = 0.012) were higher in AA. β-Cell function relative to IS was higher in AA vs. AW (259.5 ± 35.3 vs. 168.8 ± 25.1 mg/kg FFM/min, p = 0.043).
  
  
  CONCLUSIONS
  Racial differences in insulin secretion can be demonstrated with the clamp technique in obese adolescents with T2DM. Similar to non-diabetic youth, AA adolescents with T2DM compared with their AW counterparts have an upregulated β-cell function relative to IS, the reasons for which remain to be investigated.
authors.affiliation: Division of Weight Management and Wellness, Children's Hospital of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Fida
authors.initials: F
authors.lastname: Bacha
authors.forename: Neslihan
authors.initials: N
authors.lastname: Gungor
authors.forename: Sojung
authors.initials: S
authors.lastname: Lee
authors.forename: Silva A
authors.initials: SA
authors.lastname: Arslanian
mesh_terms: D000293:Adolescent; D001741:Black or African American; D003924:Diabetes Mellitus, Type 2 / Q000208:ethnology* / Q000503:physiopathology*; D005260:Female; D015309:Glucose Clamp Technique; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance / Q000502:physiology*; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000502:physiology*; D008297:Male; D009765:Obesity / Q000208:ethnology / Q000503:physiopathology*; D014481:United States; D044465:White People
chemical_list: D006442:Glycated Hemoglobin; D007328:Insulin; C517652:hemoglobin A1c protein, human