The patient’s fasting plasma glucose level is high (above 126 mg/dL) and the oral glucose tolerance test is normal (below 200 mg/dL). Therefore, the test with the abnormally high result (the fasting plasma glucose) needs to be repeated. The oral glucose tolerance test was normal and does not need to be repeated. The diagnosis of diabetes mellitus is not excluded because one of the tests was abnormal. If, upon repeat testing, the FPG is normal, then the diagnosis is excluded. If the repeat FPG is abnormal again, then the diagnosis of diabetes mellitus would be confirmed.