Welcome to HCM.
From your statement it is not clear whether he is unable to move his leg or he doesn't feel sensation in the leg, whether one leg is affected or both legs are affected.
Since he is Diabetic and has heart problem also, both these conditions are possible.
In case he is having high blood pressure
, there could be intracranial bleeding (Stroke
) leading to weakness in the limbs
In case of uncontrolled Diabetes
he may have peripheral Neuropathy
with altered or lack of sensation to touch and pain.
He needs detailed investigation to find out the cause and only then proper treatment can be started.