The potential of weight gain and the risk of diabetes occurs with all atypical (current generation) antipsychotics, some more than others. However each person responds differently to each medication. With some antipsychotics I was prescribed I didn't encounter any concerns as regards weight gain. The potential risk of diabetes can be treated with Metformin.
However only a psychiatrist would understand the clinical specifics
so it would be worth discussing this with them. Be sure to inform them
of any physical health conditions you have and have the physical doctor who is treating them speak to your psychiatrist. Many people have been helped by that medication and your psychiatrist would be able
to explain to you how it works. Also the medication website
should have further information you can discuss with your psychiatrist.
If they note any concerns you can discuss potential alternative options as well.