Ah ok I didn't realise you were newly diagnosed.
Your body is adjusting after the massive shock to it developing diabetes. You will gain back the weight you lost whilst this is happening.
Once you are sorted and stable then start to lose weight if you need to.
Losing weight can only be done by limiting calories/carbs and exercise.
But do not do this until you are stable with your diabetes otherwise you will never sort yourself out
Once you have good numbers you can work out your carb/insulin ratio and eat what you want.