The purpose of this clinical study is to learn about the safety and effects of the study medicine to help adults with obesity or overweight and type 2 diabetes lose weight. Being overweight or obese means carrying too much body weight. Type 2 diabetes is a condition where there is too much sugar in the blood. The study medicine is given by a shot under the skin in the belly area. The participants will be trained to do this at home once every week. About 660 out of 1000 adults will also receive the study medicine and about 330 out of 1000 adults will receive placebo. A placebo does not have any medicine in it but looks just like the medicine being studied. The investigators will compare the experiences of people receiving the study medicine to those of the people who do not. This will help us assess if the study medicine is safe and effective. People will take part in this study for about 21 months. During this time, they will have about 14 study visits at the site and 5 over the phone.