Background and Objectives: Individuals with type 2 diabetes mellitus (T2DM) have an increased risk of cardiovascular disease. Arterial stiffness is an independent prognostic marker for cardiovascular disease development. We aimed at determining the effect of two different sodium-glucose co-transporter-2 (SGLT-2) inhibitors on ambulatory arterial stiffness in individuals with T2DM. Materials and Methods: In this single-center, single-arm, prospective study performed from January 2020 to August 2021, we planned to enroll adult subjects with T2DM and stable antidiabetic and antihypertensive treatment, assigned either to empagliflozin or dapagliflozin for 6 months. All eligible subjects underwent ambulatory blood pressure monitoring. We set as the primary efficacy outcome the change in ambulatory pulse wave velocity (PWV) from baseline to week 24. Results: We finally enrolled 46 diabetic subjects, with a mean age of 62.89 (8.53) years and mean T2DM duration of 9.72 (6.37) years. Thirty patients received dapagliflozin, while sixteen patients received empagliflozin. Due to COVID-19 pandemic restrictive measures during the study, the mean follow-up period extended from 6 months to 9.98 (3.27) months. Regarding the prespecified primary efficacy outcome, we found that the SGLT-2 inhibitor treatment did not have a significant effect on PWV (p = 0.65). Prior history of cardiovascular disease did not significantly affect the observed effects. Other indices of arterial stiffness, such as augmentation index and central pulse pressure, were not significantly affected, neither by empagliflozin nor by dapagliflozin. Conclusions: SGLT-2 inhibitor treatment with empagliflozin or dapagliflozin in subjects with T2DM failed to improve ambulatory PWV over a mean follow-up of 10 months. Registration number: ISRCTN88851713.