You are being treated for nail fungal infection. Fluconazole does not work in many patients due to anti fungal resistance. Kindly request your dermatologist for a nail culture for fungus and sensitivity. Based on the report, appropriate anti fungal needs to be prescribed. It takes a few weeks for the report . Till then, detailed blood tests for diabetes need to be done. If treated properly, nail fungal infections heal well. However, since nail growth is slow- it takes 6 months for a healthy pink appearance of the affected nails. Kindly consult dermatologist and get investigated fully.