OGTT 0' 120' LIS Code: OGTT 0 120

The oral glucose tolerance test (OGTT) 0'–120' checks how your body handles glucose by measuring blood sugar at two points: once while fasting, and again two hours after drinking a glucose solution. Comparing the two readings shows whether your body is processing glucose normally, is on the way to developing diabetes, or is already in the diabetic range.

It's a useful test if you have symptoms that could point to blood sugar problems, such as unusual thirst, needing to urinate more than usual, or fatigue that doesn't have an obvious cause. It's also commonly used for people with a family history of diabetes, those who are overweight, and pregnant women being screened for gestational diabetes.

The fasting sample gives a baseline glucose level, and the sample taken two hours later shows how well your body has brought glucose levels back down after the drink. Together, these two results are one of the standard ways diabetes and pre-diabetes are diagnosed.

Fasting for 8–12 hours beforehand is required, and it's best to avoid smoking, alcohol, and strenuous exercise in the 24 hours before the test, as these can all affect the result. Only a blood sample is needed, with two draws taken during the same visit, and results are available in around 4 hours.