Gestational diabetes mellitus (GDM) is defined as impaired glucose tolerance of various degrees first manifested during pregnancy. The primary aim of treating GDM is to optimize glycaemic control and improve pregnancy outcomes. Also, as part of treatment, it is recommended to continue or initiate exercising with moderate intensity. However, available data on the effects of physical activity on GDM are based on a small number of trials. The aim of the trial is to examine and add new scientific evidence on possible health-related effects of application of structured programme consisting of aerobic and resistance exercises on the course and outcomes of GDM. Primary goal of research is to determine how proposed exercise programme effects glycaemic control, rate of complications during pregnancy, labour, delivery, immediate after delivery and health status of newborn. Main hypothesis is that parameters of glycaemic control, course of GDM, complications during delivery and birth outcomes directly and significantly correlate with participation in structured programme of exercise. Research will be conducted as experimentally designed randomized controlled trial. Participants will be pregnant women diagnosed with GDM, age between 20 and 40, without comorbidities. Women in the experimental group will be included in exercise programme two times per week with duration of 50 minutes. Training sessions will start right after the diagnosis and will be performed until the end of the pregnancy. The training protocol will follow international guidelines (ACOG, 2001; ACOG, 2002; ADA, 2008; NICE, 2008; ADA 2011). Women in the control group will receive standard medical care.