Welcome to HCM
I am glad that you are taking care of health really well,as long standing diseases like Diabetes
,what you have described it is hyperthyroid state detected by routine investigation or clinical finding?
If it is mild and non malignant it will be controlled by taking antithyroid drugs
and keep your diabetes and BP under control.
For over active Throid other treatment option are dose of radio active Iodine
and surgery,which will be decided by your treating Physician if you need any.
Diet has little role some times drugs which are used to treat heart condition may cause thyroid abnormality.