Tatovic, D., Luzio, S., Dunseath, G., Liu, Y., Alhadj Ali, M., Peakman, M., Dayan, C. M., O'Keefe, A., Stenson, R., Pell, J., Howell, A., Arif, S., Bayly, G., Thorogood, N., Green, K., Andrews, R. C., McLintock, N., Leech, N., Kyne, D., and Joseph, F.
Aims To determine if urine C-peptide/creatinine ratio is a useful tool for monitoring β-cell function in new-onset Type 1 diabetes. Methods Data were obtained from a prospective immunomodulation study in people with Type 1 diabetes ≤ 3 months from diagnosis, with a standard mixed-meal tolerance test and measurement of urine C-peptide/creatinine ratio carried out at 0, 3, 6, 9 and 12 months. The change in the insulin-dose-adjusted HbA1c level was also correlated with the change in serum/urine C-peptide level during the 12-month follow-up period. Results A significant reduction in urine C-peptide/creatinine ratio, measured after a mixed-meal, was reached at 9 months (−45.4%), whilst the reduction in stimulated serum C-peptide level reached significance after 3 months (−54.7%) in placebo-treated participants. Neither change in stimulated serum C-peptide nor change in urine C-peptide level correlated with each other, and nor did change in insulin-dose-adjusted HbA1c level in the first 6 months, but all measures correlated significantly in the second half of the 12-month follow-up period. Conclusion Mixed-meal-stimulated urine C-peptide/creatinine ratio was similar to, although less sensitive than, stimulated serum C-peptide level in monitoring β-cell function during the first year after diagnosis. Because the former is significantly less invasive, it warrants inclusion in further studies in Type 1 diabetes and may represent an attractive alternative outcome measure in cohort studies and in children. [ABSTRACT FROM AUTHOR]