680-P: Residual ß-Cell Function in Long-Term Type 1 Diabetes Is Associated with a Fivefold Greater Mobilization of Endothelial Progenitor Cells after Exercise

Aims: β-cells can function for years after diagnosis in people with type 1 diabetes (T1D). It is unknown how C-peptide secretion impacts upon rare blood vessel protecting Endothelial and Hematopoietic Progenitor Cells (EPCs and HPCs), particularly in response to cardiovascular stress, such as exercise. We compared EPC and HPC counts at rest and after acute exercise in clinically diagnosed people with T1D with undetectable and high C-peptide. Methods: After quantification of stimulated C-peptide, 11 participants with undetectable C-peptide (Cpepund 200 pmol/L) were recruited, with no differences in age, fitness or HbA1c, while the Cpephigh group had shorter diabetes duration (27±13 vs. 11±3 years, p=0.01). After a maximal exercise test, participants attended a third visit to complete 45mins of walking at 60%VO2peak. Blood samples were taken at rest, immediately and 1 hour post exercise. Two HPC and five EPC phenotypes were enumerated by flow cytometry. Data (mean±SD) were analysed by two-way ANOVA and t-test with significance accepted at p≤0.05. Results: The Cpephigh group displayed higher rest values of HPCs than the Cpepund group, and increased rest to post exercise mobilization (p Conclusion: People with T1D who maintained a high residual β-cell function had increased counts of HPCs and EPCs, and sustained a >5 fold exercise mobilization of EPCs compared to people with no C-peptide. Future research needs to understand if these differences are due to clinical characteristics or the potential direct impact of C-peptide upon vasculature. Disclosure K. Smith: None. J. Scragg: None. A. Bashir: None. A. Flatt: None. E.J. Stevenson: None. T.J. McDonald: None. R.A. Oram: None. J.A. Shaw: Advisory Panel; Self; Medtronic. Speaker’s Bureau; Self; Novo Nordisk A/S. M.D. Ross: None. D.J. West: None. Funding Diabetes Research & Wellness Foundation (to D.J.W.)