Bjornstad P, et al. - As lean and obese adolescents with type 1 diabetes mellitus (T1DM) have marked insulin resistance (IR) and metformin improves surrogate markers of IR in T1DM, researchers investigated the effects of metformin on directly measured IR and vascular health in youth with T1DM. Forty-eight adolescents (12 to 21 years of age; 40% body mass index [BMI] ≥90th percentile; 56% female) with T1DM and 24 nondiabetic control participants were analyzed performing magnetic resonance imaging of the ascending (AA) and descending aorta to assess pulse wave velocity, relative area change, and maximal (WSSMAX) and time-averaged (WSSTA) wall shear stress. Compared with control participants, adolescents with T1DM displayed IR and impaired vascular health. Further, IR improved on reception of metformin in the adolescents with T1DM, regardless of baseline BMI, and BMI, weight, fat mass, insulin dose, and aortic and carotid health. Metformin thus seems to be a promising cardioprotective intervention in T1DM.