The aim of the present study was to evaluate the add-on effect of acarbose therapy in oxidative stress, and the lipid and inflammatory profiles of patients with type 2 diabetes mellitus (T2DM) treated with insulin. This was an open and unblended study. Patients (n=134) with T2DM (haemoglobin A1c range, 9.0-12.0%) were recruited. After continuous subcutaneous insulin infusion for 7 days for initial rapid correction of hyperglycaemia, a premixed insulin titration period (duration, 4-6 days) subsequently followed. Patients were then randomized (1:1) into two groups as follows: An acarbose plus pre-mixed 30/70 insulin group or a pre-mixed 30/70 insulin only group; each group received treatment for 2 weeks. Plasma high-sensitivity C-reactive protein (Hs-CRP), 8-iso-prostaglandin F2α (8-iso PGF2α), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6 levels were measured before and after therapy. Patients that received acarbose plus insulin demonstrated greater reduction in 8-iso PGF2α, Hs-CRP, TNF-α, IL-1β and IL-6 levels when compared with the insulin only patients. Thus, acarbose add-on insulin therapy was identified to be associated with greater improvements in oxidative stress and inflammation in patients with T2DM when compared with those that received insulin only therapy.