The aim of this graduate thesis was to explore the perinatal outcome of gestational diabetes mellitus in our referral center in Zagreb. All over the world, physicians are faced with many challenges when it comes to diabetes, metabolic syndromes or other endocrinological disturbances. Modern lifestyles, especially western diets create a favorable background for the emergence of this type of conditions. This environmental factor coupled with genetic predispositions results in an increased interest for GDM as it is a partially a preventable disease. In our study, we used a database of 2362 pregnant women suffering from this condition. We found that these women had a statistically higher prevalence of hypertension before and throughout the pregnancy. This risk factor led to a higher number of operative delivery (C-sections). Newborns also presented with a higher proportion of macrosomia than in the general population. This feature; in addition to the serious neonatal complications such as hyperbilirubinemia, hypoglycemia and respiratory disturbances, justifies the use of c-sections as a mode of delivery. Our results emphasize the importance of proper follow up of women in pregnancy; starting from early screening to appropriate management using modern imaging techniques and adequate nutritional approach.