Severe uncontrolled diabetes
for a long time damages almost all the systems of body which include heart,kidneys,eyes,blood vessels etc.
Heart diseases and blood vessel diseases are the biggest complication of uncontrolled diabetes.
Adults with uncontrolled diabetes have two to four fold chances of developing heart related death rates as compared to non diabetics.
Your mother must definitely be having some cardiac complications like chest pain
or breathlessness which has prompted the doctors to order for angigraphy.
Let the doctors decide about the mode of investigations and treatment of your mother.
They act in the best interest of the patient and should not be seen with doubt.