your mom's swollen legs and blisters on her toes are concerning. i'm assuming your mom has diabetes since you said she has high sugar levels. people with diabetes are prone to getting serious foot infections and it would be good for a healthcare professional to examine her feet. also there are several conditions that can cause swelling in the legs. it would be helpful for your doctor to check to see if her swelling could be related to a heart problem or kidney problem.
my 82 yr old mother has swollen legs and has developed blisters on her big toes. she is not overweight. she has copd. she has had high sugar levels. her blood pressure flecuates - sometimes high sometimes low. she has received steroid shots for her back and legs. her doctor has assured her that the batch of steroids were not bought from the recent outbreak of menengitis.