Obtain a urinalysis with culture, complete blood count (CBC), and an abdominal/pelvic CT scan with contrast to evaluate for pyelonephritis.

Administer antiemetic medication immediately to control vomiting and delay diagnostic testing until symptoms resolve.

Recommend oral antibiotics empirically without laboratory confirmation since the patient has typical urinary symptoms and a history of diabetes.

Schedule an ultrasound of the lower abdomen only to check for bladder abnormalities before any laboratory testing.