Insulin resistance (IR) is defined clinically as the inability of a known quantity of exogenous or endogenous insulin to increase glucose uptake and utilization. In recent years the increasing role of IR in the pathogenesis of type 1 diabetes mellitus (T1DM) related complications has been taken into account. The aim of this article is to discuss the possible role of IR in pregnancy complicated by T1DM. At the moment, there is no doubt that IR is not only frequently observed in T1DM patients, but also is a separate risk factor of several complications in nonpregnant patients. The role of IR in pregnancy complicated by T1DM has not been widely studied yet. However, data from the studies on different populations showed that IR may predispose to such conditions as miscarriage, preeclampsia and macrosomia. Interestingly all of these are more frequently diagnosed in women with T1DM in comparison to healthy subjects. The literature on the role of IR in human pregnancy is relatively rich. However despite its significance in pathophysiology of T1DM and its complications in general population, there is a lack of understanding of how it affects maternal and fetal health in pregnancy complicated by this disease. Nonetheless, based on the available literature, IR may be proposed as an additional factor modifying pregnancy outcome in woman with T1DM. Therefore, measures that might reduce IR such as good glycemic control and control of weight gain should be recommended for every woman with T1DM, optimally when planning but also throughout the pregnancy