Appropriate management of hyperglycemia is crucial for patients with type 2 diabetes. Aim of the FADOI-DIAMOND study was to evaluate real-world management of type 2 diabetic patients hospitalized in Internal Medicine wards (IMW) and the effects of a standardized educational intervention for IMW staff. DIAMOND has been carried out in 53 Italian IMW, with two cross-sectional surveys interspersed with an educational program (PRE phase and POST phase). In PRE phase, each center reviewed the charts of the last 30 hospitalized patients with known type 2 diabetes. An educational program was conducted in each center by means of the "outreach visit," a face-to-face meeting between IMW staff and a trained external expert. Six months after, each center repeated the data collection (POST phase), specular to the PRE. A total of 3,167 patients were enrolled (1,588 PRE and 1,579 POST). From PRE phase to POST, patients with registered anthropometric data (54.1 vs. 74.9 %, p < 0.001) and in-hospital/recent measurement of glycated hemoglobin (48.2 vs. 61.4 %, p < 0.005) increased significantly. After educational program, more patients received insulin during hospitalization (68.3 vs. 63.6 %, p = 0.005). A more relevant variation in glycemia during hospitalization was observed in POST phase than PRE (-22.2 vs. -15.5 mg/dL, p < 0.001), without differences as for occurrence of hypoglycemia (12.3 vs. 11.9 %). A one-shot educational intervention led to persistent improvement in the management of hospitalized patients with type 2 diabetes and to significant better glycemic control. Further studies might evaluate the effectiveness of a more aggressive educational program, on both management and outcomes.