Relationship between fluctuations in glucose levels measured by continuous glucose monitoring and vascular endothelial dysfunction in type 2 diabetes mellitus

BACKGROUND: Fluctuations in blood glucose level cause endothelial dysfunction and play a critical role in onset and/or progression of atherosclerosis. We hypothesized that fluctuation in blood glucose levels correlate with vascular endothelial dysfunction and that this relationship can be assessed using common bedside medical devices. METHODS: Fluctuations in blood glucose levels were measured over 24 hours by continuous glucose monitoring (CGM) on admission day 2 in 57 patients with type 2 diabetes mellitus. The reactive hyperemia index (RHI), an index of vascular endothelial function, was measured using peripheral arterial tonometry (EndoPAT) on admission day 3. RESULTS: The natural logarithmic-scaled RHI (L_RHI) correlated with SD (r=-0.504; P<0.001), the mean amplitude of glycemic excursions (MAGE) (r=-0.571; P<0.001), mean postprandial glucose excursion (MPPGE) (r=-0.411; P=0.001) and percentage of time ≥ 200 mg/dl (r=-0.292; P=0.028). In 12 patients with hypoglycemia, L_RHI also correlated with the percentage of time at hypoglycemia (r=-0.589; P=0.044). L_RHI did not correlate with HbA1c or fasting plasma glucose levels. Furthermore, L_RHI did not correlate with LDL cholesterol, HDL cholesterol, and triglyceride levels or with systolic and diastolic blood pressures. Finally, multivariate analysis identified MAGE as the only significant determinant of L_RHI. CONCLUSIONS: Fluctuations in blood glucose levels play a significant role in vascular endothelial dysfunction in type 2 diabetes.