If you have diabetes then it's very important for you to take proper steps to control your blood sugar level. Diabetes may create a favorable environment for fungal to thrive in. Also, fungal infection on your fingernails and toenails may create severe damage and may cause permanent scars on your nails. Therefore, if you are suffering from any kind of infection on your finger or toe nails and if it is not properly treated and controlled then you may create permanent damage on your nail as well as finger nails.