As exercise mobilised HPCs and EPCs negative for CXCR4 and CXCR7 in the controls, but not the type 1 diabetes group, this suggests pathways other than stromal cell–derived factor-1α (SDF-1α)/CXCR4 are also impaired by deregulated glucose control seen in diabetes. Here, CXCR4 is linked to diabetes mellitus.