What is a symptom that supports a potential diagnosis of diabetes in a child?

Blurred vision is a significant symptom that supports a potential diagnosis of diabetes in a child. This symptom arises due to changes in fluid levels in the body, which can affect the lenses of the eyes. High blood sugar levels can lead to the lenses becoming swollen or changing shape, making it difficult for the child to focus clearly. In pediatric patients, this can be an early indicator of diabetes, particularly when considered alongside other classic symptoms, such as excessive thirst or frequent urination.

While the other options may be associated with various conditions, they are not as directly tied to diabetes as blurred vision. For instance, frequent headaches could result from a range of causes, including stress or dehydration. Dry skin might indicate dehydration or eczema but isn't specific to diabetes. Unexplained mood swings could be linked to many different factors, such as hormonal changes or psychological factors, and are not unique indicators of diabetes. Thus, among the options provided, blurred vision is the most relevant symptom suggesting diabetes in children.