OBJECTIVE: The effect of glycemic variability (GV) on cardiovascular risk has not been fully clarified in type 2 diabetes. We evaluated the effect of GV, blood pressure (BP), and oxidative stress on intima-media thickness (IMT), left ventricular mass index (LVMI), flow-mediated dilation (FMD), and sympathovagal balance (low frequency [LF]/high frequency [HF] ratio) in 26 type 2 diabetic patients (diabetes duration 4.41±4.81 years; HbA1c 6.70±1.25%) receiving diet and/or metformin treatment, with no hypotensive treatment or complications. RESEARCH DESIGN AND METHODS: Continuous glucose monitoring (CGM) data were used to calculate mean amplitude of glycemic excursion (MAGE), continuous overall net glycemic action (CONGA)-2, mean blood glucose (MBG), mean postprandial glucose excursion (MPPGE), and incremental area under the curve (IAUC). Blood pressure (BP), circadian rhythm, and urinary 15-F2t-isoprostane (8-iso-prostaglandin F2α [PGF2α]) were also evaluated. Subjects were divided into dipper (D) and nondipper (ND) groups according to ΔBP. RESULTS: IMT and LVMI were increased in ND versus D (0.77±0.08 vs. 0.68±0.13 [P=0.04] and 67±14 vs. 55±11 [P=0.03], respectively). MBG, MAGE, and IAUC were significantly associated with LF/HF ratio at night (r=0.50, P=0.01; r=0.40, P=0.04; r=0.41, P=0.04, respectively), MPPGE was negatively associated with FMD (r=-0.45, P=0.02), and CONGA-2 was positively associated with LVMI (r=0.55, P=0.006). The Δsystolic BP was negatively associated with IMT (r=-0.43, P=0.03) and with LVMI (r=-0.52, P=0.01). Urinary 8-iso-PGF2α was positively associated with LVMI (r=0.68 P<0.001). CONCLUSIONS: An impaired GV and BP variability is associated with endothelial and cardiovascular damage in short-term diabetic patients with optimal metabolic control. Oxidative stress is the only independent predictor of increased LV mass and correlates with glucose and BP variability.