Adjusted mean difference over 7 years of DCCT follow-up between intensively treated stimulated C-peptide responders vs. nonresponders with up to a 5-year duration (<60 months) and the change per 50% increase in C-peptide obtained using log(C-peptide) in a linear model* for HbA_1c (as % and mmol/mol) and total insulin dose units/kg/day