Preparation for the glucose tolerance test
The glucose tolerance test is usually performed in the morning. It is important that you appear sober for the test. On the one hand, this means that you should avoid nicotine, alcohol, coffee and tea twelve hours before the test begins.
It also means that you should not eat or drink anything except water for about ten hours before the test. In order to have reliable results, the German Diabetes Society recommends that you keep your eating habits as usual at least three days before the start of the test, i.e. not to change them: So do not follow any diets in order to positively influence the test result. This will only falsify the test result! At best, consume more than 150g carbohydrates per day.
Procedure of the glucose tolerance test
First, blood is taken from the vein, fingertip or earlobe to determine your fasting blood glucose. You will then be given a sweet liquid, which you must drink in less than 5 minutes. This liquid contains 75 g glucose in 250 to 300 ml of water. After two hours, blood is taken again and your blood sugar level is determined.
Evaluation and standard values
During the evaluation of the glucose tolerance test, the own blood sugar value after two hours is compared with the standard values after two hours. If the own blood sugar value is too high, it indicates that the body could not sufficiently use the blood sugar (glucose) and/or glucose was not sufficiently taken up into the cells. A cause for this can be a disturbed insulin metabolism – as with diabetes mellitus.
Insulin is responsible for lowering the blood sugar level or for the absorption of blood sugar into the cells. The standard values are listed below: Fasting blood sugar: blood sugar after 120 minutes: With the glucose tolerance test is to be examined particularly on a blood sugar utilization disturbance in the sense of a diabetes. Increased blood sugar values indicate the sugar disease. But what is diabetes and how can you recognize it?
- Healthy: < 100 mgdl (< 5.6 mmol/l)
- Disturbed blood sugar metabolism: 100 – 125 mg/dl (5.6 to 6.9 mmol/l)
- Diabetes Mellitus: From >125 mg/dl (>6.9 mmol/l)
- Healthy: < 140 mgdl (< 7.8 mmol/l)
- Disturbed blood sugar metabolism: 140 to 199 mgdl (7.8 to 11 mmol/l)
- Diabetes mellitus: > 199 mgdl (> 11 mmol/l)
