Thanks for your query.Your 73 years on\ld father who is known diabetic had swelling of the leg and is Hospitalized.Based on the facts it appears that he has developed Cellulitis
of the leg (An infection of a Subcutaneous tissue
) which is common in diabetic patients.Please check his blood sugar levels to see whether his diabetes
is under control or not. Depending upon the finding consult some Diabetologist
foe proper monitoring of blood sugar levels.It is vital important for him to have his diabetes to be under control to prevent the cellulitis to spread further..Since he is hospitalized and under supervision and care of a surgeon he should recover completely within 2 to 3 weeks .