Insulin therapy is frequently needed to achieve adequate glycaemic control in type 2 diabetes mellitus (T2DM), but often at the expense of weight gain. Insulin-induced weight gain is obviously undesirable in an already overweight population and may negatively affect blood pressure, lipid levels, inflammatory and fibrinolytic parameters, adipocytokines and also deter further optimization of insulin therapy. It is unknown what determinants predict insulin-induced weight gain in type 2 diabetes mellitus.