A model-based approach to sample size estimation in recent onset type 1 diabetes

Diabetes Metab Res Rev. 2016 Nov;32(8):827-834. doi: 10.1002/dmrr.2800. Epub 2016 Apr 21.


Background: The area under the curve C-peptide following a 2-h mixed meal tolerance test from 498 individuals enrolled on five prior TrialNet studies of recent onset type 1 diabetes from baseline to 12 months after enrolment were modelled to produce estimates of its rate of loss and variance.

Results: Age at diagnosis and baseline C-peptide were found to be significant predictors, and adjusting for these in an ANCOVA resulted in estimates with lower variance.

Conclusions: Using these results as planning parameters for new studies results in a nearly 50% reduction in the target sample size. The modelling also produces an expected C-peptide that can be used in observed versus expected calculations to estimate the presumption of benefit in ongoing trials. Copyright © 2016 John Wiley & Sons, Ltd.

Keywords: C-peptide; clinical trial; type 1 diabetes.

Publication types

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

MeSH terms

  • Adolescent
  • Adult
  • Age of Onset
  • Area Under Curve
  • Biomarkers / blood*
  • C-Peptide / blood
  • Child
  • Child, Preschool
  • Diabetes Mellitus, Type 1 / physiopathology*
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Middle Aged
  • Models, Statistical*
  • Prognosis
  • Sample Size
  • Young Adult


  • Biomarkers
  • C-Peptide