although metoprolol is a weak hypertensive and is usally insufficient to control high blood pressure.
but since your BP is now controlled you dont need to change drug. Infact it is good for your heart. because long standing diabetic patients do have some negative effects on heart.
secondly start taking statin( cholesterol lowering drug) , no matter even if you have a normal cholesterol level, you require this medication
Next Steps
add atorvastatin 20 mg night time daily.