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oGTT is used to screen for diabetes in asymptomatic individuals and also to screen for gestational diabetes mellitus (GDM) in pregnant women.


According to the WHO, gestational diabetes mellitus is considered to be a disorder of glucose metabolism of various degrees, which occurs during pregnancy and in most cases resolves spontaneously during the six-week period. (WHO, 2013). Screening  in all pregnant women, it is performed between the 24th and 28th TG using the standard oGTT. In pregnant women with present risk factors, the test is performed earlier, at the first visit to the antenatal clinic



The test is done on an empty stomach (do not eat for at least 8 hours), the examinee may drink clean water. Three days before the test, he should have normal eating habits, the day before the test, increased physical exertion should be ruled out. Medicines with anti-insulin effect (corticoids, thyroxine, betamimetics, progesterone) will be used by the patient on the day after the end of the test. Throughout the test, the examinee must maintain physical peace.



Venous sampling is recommended for oGTT testing, the criteria for test evaluation apply to venous plasma!  drinks 75 g of glucose dissolved in 250 ml of water  for 3-5 minutes.

Exercise glycemia is taken as standard  after 2 hours of glucose administration. For pregnant women, a three-point curve is recommended -  collection after 1 and 2 hours after glucose administration. Venous blood is drawn  into a tube with the antiglycolytic agent NaF  (on request - Sarstedt or Vacutainer tube), glucose must be determined no later than 24 hours after collection. When collected in a standard biochemical gel tube, it is required  centrifugation within 30 minutes of collection.

The test is not performed in acute illness (virosis, hyperemesis of pregnant women, etc.) and in fasting blood glucose ≥ 7.0 mmol / l.

Table 1 shows the evaluation of the oGTT test depending on the type of collection (venous plasma / capillary plasma). When evaluating oGTT in pregnant women,  at least one elevated blood glucose value is evaluated as GDM.

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