Metabolic Contrasts Between Youth and Adults With Impaired Glucose Tolerance or Recently Diagnosed Type 2 Diabetes: I. Observations Using the Hyperglycemic Clamp

Diabetes Care. 2018 Aug;41(8):1696-1706. doi: 10.2337/dc18-0244. Epub 2018 Jun 25.


Objective: To compare insulin sensitivity (M/I) and β-cell responses in youth versus adults with impaired glucose tolerance (IGT) or drug-naïve, recently diagnosed type 2 diabetes.

Research design and methods: In 66 youth (80.3% with IGT) and 355 adults (70.7% IGT), hyperglycemic clamps were used to measure 1) M/I, 2) acute (0-10 min [first phase]) C-peptide (ACPRg) and insulin (AIRg) responses to glucose, 3) steady-state C-peptide and insulin concentrations at plasma glucose of 11.1 mmol/L, and 4) arginine-stimulated maximum C-peptide (ACPRmax) and insulin (AIRmax) responses at plasma glucose >25 mmol/L. The fasting C-peptide-to-insulin ratio was used as an estimate of insulin clearance.

Results: Insulin sensitivity was 46% lower in youth compared with adults (P < 0.001), and youth had greater acute and steady-state C-peptide (2.3- and 1.3-fold, respectively; each P < 0.001) and insulin responses to glucose (AIRg 3.0-fold and steady state 2.2-fold; each P < 0.001). Arginine-stimulated C-peptide and insulin responses were also greater in youth (1.6- and 1.7-fold, respectively; each P < 0.001). After adjustment for insulin sensitivity, all β-cell responses remained significantly greater in youth. Insulin clearance was reduced in youth (P < 0.001). Participants with diabetes had greater insulin sensitivity (P = 0.026), with lesser C-peptide and insulin responses than those with IGT (all P < 0.001) but similar insulin clearance (P = 0.109).

Conclusions: In people with IGT or recently diagnosed diabetes, youth have lower insulin sensitivity, hyperresponsive β-cells, and reduced insulin clearance compared with adults. Whether these age-related differences contribute to declining β-cell function and/or impact responses to glucose-lowering interventions remains to be determined.

Trial registration: NCT01779362 NCT01779375 NCT01763346.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Blood Glucose / metabolism*
  • C-Peptide / blood
  • Child
  • Diabetes Mellitus, Type 2 / diagnosis
  • Diabetes Mellitus, Type 2 / metabolism*
  • Fasting / blood
  • Female
  • Glucose Clamp Technique* / methods
  • Glucose Intolerance / metabolism*
  • Glucose Tolerance Test
  • Humans
  • Insulin / blood
  • Insulin Resistance* / physiology
  • Insulin-Secreting Cells / metabolism
  • Male
  • Middle Aged
  • Young Adult


  • Blood Glucose
  • C-Peptide
  • Insulin

Associated data