Thrush is a fungal infection that is known as an oral yeast infection, and along with the symptoms there are the white patches in the mouth and on the tongue. The white patches should not be scrubbed or wiped from the mouth and tongue as these can cause soreness and open the diabetic up for other types of oral infections.

There can be burning in the mouth and on the tongue as a result of thrush in some diabetics, there can  be pain and difficulty swallowing. There can be raised lesions in the mouth on the tongue or inner cheeks, the gums might bleed and in severe cases of thrush the lesions can spread to the esophagus.