Lots of people have T2D without being obese.  And a lot of people are obese who do not have T2D.  T2D and obesity are both caused by eating too many calories, especially the type of calories that come from refined carbs, which the body is not designed/evolved to handle.  Too much refined carbs spikes insulin.  If this happens too much, the background level of insulin goes high, and you have T2D and/or obesity.  If you don't want too much sugar in your bloodstream, don't eat too much sugar and foods that are converted into sugar (glucose), like carbs.  This is not rocket science.  A ketogenic diet and intermittent fasting will break up the logjam of too much sugar in the blood.