What does a load test reveal?
A routine fasting glucose test remains normal for a long time even when the body's ability to absorb sugar is already impaired. A load test reveals this problem: the patient drinks a solution with 75 g of glucose, and after 2 hours its level is measured. If it is elevated, but does not reach diabetic values, impaired glucose tolerance is established - a condition in which lifestyle changes can still prevent diabetes. A separate mandatory indication is screening for gestational diabetes in pregnant women at 24–28 weeks. The preparation requirements are strict: 3 days of normal eating without limiting carbohydrates, then 8–14 hours of fasting, during the test you cannot eat, smoke or walk.
Why preparation is so important
The laboratory result is a number, but the correct number can only be obtained if the rules are followed. Eating changes the levels of glucose, lipids and a number of enzymes significantly; physical activity the day before increases CK and AST; smoking affects hormones; time of day is critical for cortisol and testosterone.
Therefore, a “bad analysis” often turns out to be a consequence of impaired preparation, and not an illness, and leads to unnecessary examinations and prescriptions.
General rules for donating blood
- on an empty stomach 8–12 hours, you can drink water
- Eliminate alcohol and intense exercise per day
- no smoking in an hour
- donate blood before physiotherapy, x-rays and massage
- Take medications in advance by agreeing with your doctor
- for hormones in women, take into account the day of the cycle
How to read the result
Reference values depend on the method and equipment of the laboratory, so it is correct to compare results only within the same laboratory. A deviation of a few percent from the normal limit in itself rarely matters - the overall picture and dynamics are important. It is up to the physician to interpret the analysis: an isolated indicator without a clinical context is often misleading.