Abstract
BackgroundMany individuals with type 1 diabetes retain residual beta-cell function. Sustained endogenous insulin and C-peptide secretion is associated with reduced diabetes related complications, but underlying mechanisms remain unclear. Lower circulating numbers of endothelial and hematopoietic progenitor cells (EPCs and HPCs), and the inability to increase the count of these cells in response to exercise, are also associated with increased diabetes complications and cardiovascular disease. It is unknown whether residual beta-cell function influences HPCs and EPCs. Thus, this study examined the influence of residual beta-cell function in type 1 diabetes upon exercise-induced changes in haematopoietic (HPCs) and endothelial progenitor cells (EPCs).MethodsParticipants with undetectable stimulated C-peptide (n=11; Cpepund), 10 high C-peptide (Cpephigh; >200 pmol/L), and 11 non-diabetes controls took part in this observational exercise study, completing 45 minutes of intensive walking at 60% . Clinically significant HPCs (CD34+) and EPCs (CD34+VEGFR2+) phenotypes for predicting future adverse cardiovascular outcomes, and subsequent cell surface expression of chemokine receptor 4 (CXCR4) and 7 (CXCR7), were enumerated at rest and immediately post-exercise by flow cytometry.ResultsExercise increased HPCs and EPCs phenotypes similarly in the Cpephigh and control groups (+34-121% across phenotypes, p<0.04); but Cpepund group did not significantly increase from rest, even after controlling for diabetes duration. Strikingly, the post-exercise Cpepund counts were still lower than Cpephigh at rest.ConclusionsResidual beta-cell function is associated with an intact exercise-induced HPCs and EPCs mobilisation. As key characteristics (age, fitness, HbA1c) were similar between groups, the mechanisms underpinning the absent mobilisation within those with negative C-peptide, and the vascular implications, require further investigation.
Highlights
Residual beta-cell function can persist in individuals with established type 1 diabetes, with between 35% to 80% of participants estimated to have detectable function at >5 years post diagnosis [1, 2]
We show that a high residual beta-cell function in type 1 diabetes is associated with intact exercise-induced increases in circulating haematopoietic stem/ progenitor cells (HPC) and endothelial progenitor cells (EPCs) numbers, comparable to non-diabetes controls
In those with undetectable Cpeptide, rapid mobilisation in response to exercise appears to be lost. This is despite similar HbA1c, age, and fitness between type 1 diabetes groups, all clinical characteristics that previously have been demonstrated to influence circulating counts [22, 26, 36]
Summary
Residual beta-cell function can persist in individuals with established type 1 diabetes, with between 35% to 80% of participants estimated to have detectable function at >5 years post diagnosis [1, 2]. Compared to matched healthy controls, individuals with type 1 diabetes have reduced circulating counts of both HPCs and EPCs [19–24], with lower resting counts associated with increased occurrence of diabetes complications and cardiovascular disease (CVD) [19, 20, 25, 26]. Lower circulating numbers of endothelial and hematopoietic progenitor cells (EPCs and HPCs), and the inability to increase the count of these cells in response to exercise, are associated with increased diabetes complications and cardiovascular disease. It is unknown whether residual beta-cell function influences HPCs and EPCs. this study examined the influence of residual beta-cell function in type 1 diabetes upon exerciseinduced changes in haematopoietic (HPCs) and endothelial progenitor cells (EPCs)
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