Type 2 diabetes in youth: are there racial differences in β-cell responsiveness relative to insulin sensitivity?

Pediatr Diabetes. 2012 May;13(3):259-65. doi: 10.1111/j.1399-5448.2011.00820.x. Epub 2011 Sep 20.

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.

Research design and 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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • African Americans*
  • Diabetes Mellitus, Type 2 / ethnology*
  • Diabetes Mellitus, Type 2 / physiopathology*
  • European Continental Ancestry Group*
  • Female
  • Glucose Clamp Technique
  • Glycated Hemoglobin A / metabolism
  • Humans
  • Insulin / metabolism
  • Insulin Resistance / physiology*
  • Insulin Secretion
  • Insulin-Secreting Cells / physiology*
  • Male
  • Obesity / ethnology
  • Obesity / physiopathology*
  • United States

Substances

  • Glycated Hemoglobin A
  • Insulin
  • hemoglobin A1c protein, human