Hi, thanks for the query to H.C.M.
In this type of cases weights of patient matters, since from the last 12 yrs your's mother is a known case diabetes
and she is on both type of treatment as fro type 1 and fro type 2.
Blisters ( brown patches over legs with eruptions are formed) are a common complaint of diabetic patient .
Due to presence of sugar in excess amount underneath the skin the root cause of these skin problems.
are two main bacteria which are responsible for these patches.
Treatment is very simple.
Cleans the wound some anti septic solution.
Regular control of blood sugar level at any cost.
Once they erupted ( blisters) , diabetic patient have to take regular course of antibiotics after consultation of a doctor.
Regards . Dr. HET