April 30, 2006
Question from Wilmington, North Carolina, USA:
My mother was given a glucose tolerance test by a neurologist. It came back positive. She lives in a nursing home. The facilities doctor did a strip test and said "No, she is not diabetic." Now, weeks later, her feet and lower legs are swollen with slight discoloration around the toes. She cannot walk due to degenerative disk disease. Are glucose tolerance tests more accurate at diagnosing diabetes than strips or regular blood work?
Yes, the most sensitive test for diagnosing diabetes is the oral glucose tolerance test. However, knowing the numbers and how the test were done are crucial. The test should be carried out with three days of carbohydrate intake of 100 grams per day. After an overnight fast, the patient is given a glucose load of 75 grams with fasting and two hour post glucose load samples for glucose are taken. If patients do not have adequate carbohydrate intake prior to the test, it can be a cause of a false positive test. Glucose determinations using strips for glucose determinations are not as sensitive as using laboratory determinations. The foot changes you are describing may not be unique to diabetes and could be caused by other conditions.