Hello,
Since your father is suffering from uncontrolled diabetes,the diabetic nephropathy seems to be the likely cause for ankle swelling however uncontrolled hypertension or congestive heart failure may also result in swelling of ankles.
There could be additional element of neuropathy as well as peripheral vascular disease which might have resulted in painless injury on ankles.
Shoes may cause blisters on ankles resulting in cellulitis of ankle.
There could be Charcot arthrpoathy which is very common with uncontrolled diabetes.
You must consult a diabetologist and get yourself evaluated and treated properly.
Thanks

hi,
just went through your query. you said he is not under proper control with his hyperglycemia... first and foremost pl consult his doctor and take necessary measures to bring it back to manageable levels.
his ankle edema may be .a possible fall out of his kidney complications as mentioned, but while giving him his drugs, pl take care there is no electrolyte imbalance... talk to a nephrologist

about the reddened spots, are they blotches or minute spots.... it may be anything from purpuric spots due to a type of blood disorder,often seen with compromised kidneys or traumatic bruises which go unfelt in people having peripheral neuropathy, another complication of diabetes

pl have a dopper study of the vascularity of the concerned leg done to rule out any arterial occlusions or angiopathy .. common in his age and disease

hope this will help