First decide which diabetic model you have to induce whether Type 1 or 2. It it is Type 1 then you can go through more reliable and specific STZ model and if it is Type 2 then you can go through diet induced or poloxamer-407 induced models. This link may be helpful to you for induction of Type 2 model:
I used Alloxan at 150 mg/kg bw by ip injection to rats. T2DM can also be induced by high fat diet to form insulin resistance with/without chemical help.