**5.1 Gestational diabetes mellitus (GDM)**

GDM is transient glucose intolerance first detected during pregnancy. Manifestation usually occurs in the second and third trimesters. After delivery, the impaired glucose metabolism is corrected, and the glucose level moves within the normal range.

At the beginning of pregnancy, the main goal of the mother's metabolism is to build up sufficient reserves of energy to be used for foetal growth [121]. With the end of the first trimester, insulin resistance of muscle and adipose tissue gradually begins to develop, reaching its peak during the third trimester. The volume of adipose tissue decreases and the supply of free fatty acids increases, which newly become the main source of energy for the maternal organism. Glucose is redirected by the placenta to the foetus. Despite significant insulin resistance development of diabetes in pregnancy usually does not occur.

The HAPO study in 2008 demonstrated a strong association between glycaemia values and the perinatal complications which was almost linear and already evident at the level of glycaemia, which until then was considered completely physiological [122]. This study led to the development of a new guideline for screening and diagnosis of gestational diabetes [123]. Our centre, like others in the Czech Republic, adopted these criteria in 2015 (**Table 4**).

The primary treatment of GDM consists of dietary control, adequate physical activity and weight management remain the cornerstones of GDM treatment.


*FPG=fasting plasma glucose; PG=plasma glucose; 75g oGTT=oral glucose tolerance test with 75g of glucose. <sup>1</sup> At least 2 measurements on separate days.*

## **Table 4.**

*Diagnostic criteria for GDM (adopted from IADPSG).*

