text: RESEARCH DESIGN AND METHODS
  For this study, 20 individuals (mean age 39.5 +/- 11.1 years) with long-standing type 1 diabetes (21.3 +/- 10.7 years) were enrolled in this prospective open-label crossover trial. After achieving optimal blood glucose control, 16 subjects were randomized to exenatide with or without daclizumab. Endogenous insulin production was determined by repeatedly measuring serum C-peptide.
  
entities.text: ['blood']
entities.type: Organism_substance
entities.entity_id: PMC-2782986-sec-02_T1
entities.text: ['serum']
entities.type: Organism_substance
entities.entity_id: PMC-2782986-sec-02_T2