Final answer:
An EMT would most likely encounter weight loss and polyuria in a patient with new-onset type 1 diabetes, due to the lack of insulin leading to the breakdown of body fats and proteins as well as increased urine production caused by excess blood glucose.
Step-by-step explanation:
The most likely signs or symptoms an EMT would encounter in a patient with new-onset type 1 diabetes are weight loss and polyuria. This is because the absence of insulin in type 1 diabetes leads to the breakdown of body fats and proteins, which can result in significant weight loss. Moreover, the excess glucose in the bloodstream will lead to increased urine production, a condition known as polyuria. However, low blood glucose levels are typically not a feature of new-onset type 1 diabetes unless the patient has taken insulin and has not eaten adequately.