Impact of glycemic variability on the levels of endothelial progenitor cells in patients with type 1 diabetes.

ABSTRACT

OBJECTIVE: A reduction in endothelial progenitor cell (EPC) count is considered to correlate with cumulative cardiovascular risk factors including hyperglycemia. This study was conducted to elucidate the influence of glycemic variability on EPC count in patients with diabetes. METHODS: In study 1, we examined the number of EPCs in 57 patients with type 1 diabetes and 43 patients with type 2 diabetes. The number of EPCs (CD34+, CD34+CD133+, CD34+CD309+, and CD34+CD133+CD309+) was counted as the number of cells per 106 events. In study 2, we examined 37 outpatients with type 1 diabetes without macrovascular complications. We assessed associations between EPC count and seven parameters of glycemic variability (blood glucose standard deviation, mean amplitude of glycemic excursion, J index, M value, mean of daily differences, low blood glucose index, and high blood glucose index), as measured by continuous glucose monitoring. We further analyzed the correlation between EPC count and the carotid intima-media thickness (IMT) in 24 patients. RESULTS: In study 1, the number of circulating CD34+ and CD34+CD133+ cells was significantly decreased in patients with type 1 diabetes relative to that in patients with type 2 diabetes (p = 0.020 and 0.036, respectively). In study 2, a univariate analysis showed that the J index was negatively correlated with logCD34+ (r = -0.342, p = 0.039). LogCD34+ was significantly negatively associated with the max IMT (r = -0.486, p = 0.012) and the mean IMT (r = -0.503, p = 0.016). CONCLUSIONS: An increase in the J index, which reflects both hyperglycemia and glycemic variability, is associated with a reduction in the EPC count, which might result in the progression of diabetic vascular complications.