You are a obese Diabetic.
As far as the black spots on you legs they may be due to varicose veins
Bulg and stagnation of venous blood
in the veins due to incompetence of the venous valves.
Avoid standing for a long time.
Keep your leg raised in sitting and lying position.
Stockings may help.
Lasix is a Diuretic
It excretes excess fluids through kidneys.
is very likely with Lasix.