The issue could be from ankle instability or due to ankle arthritis. Also with background of
Diabetes it is possible that there are other things that could be contributing to it.
The best option will be to see a Physician to start with and then take it from there.
With having diabetes, I would advice you to take very good care of your health and also get any new issues looked into at the earliest.
Hope this helps.
Dr Vinu Raj
Consultant Orthopaedic Surgeon
MBBS MRCS FRCS(Trauma&Orth)