Formerly, the investigators demonstrated in an uncontrolled proof-of principle study (NCT 01680926) that protein-rich meal replacement (PRMR) was successful in reducing daily insulin demand, HbA1c and weight in type 2 diabetes mellitus (T2DM) patients injecting >100 IE insulin/day. The aim of the present study was to investigate in a randomized-controlled trial if PRMR is also effective in T2DM patients treated with oral antidiabetic medication or insulin.