Gestational Diabetes Mellitus (GDM) comprises different forms of glucose metabolism disturbances with first recognition during pregnancy. There are a number of publications that have suggested that diabetes with onset during pregnancy is not a monogeneous disease and apart from "classical" form of GDM, which precedes type 2 diabetes development, MODY 2 diabetes, caused by monogenic defect of glucokinase gene, is relatively frequent "subtype" of gestational diabetes. The aim of our study was to estimate the risk of diabetes mellitus development, including MODY 2 diabetes, between 6 months - 10 years after delivery in 225 women with gestational diabetes. Gucokinase gene mutations and polymorphisms were performed by direct sequencing of DNA. In the present study it was shown that the frequency of glucokinase gene mutation is 6.7% in the Polish population of gestational diabetic women and 17.8% of new onset or persistant diabetes recognised during 5 years after pregnancy could be a result of this mutation. We have also observed that risk of type 2 diabetes development is about 50% in the next 5 years after delivery in women with gestational diabetes and is associated with higher levels of BMI during or after delivery and with clinical and biochemical features of insulin resistance (high values of WHR abd HOMA-R). Moreover, our study suggests that c.1253+8 C-->T polymorphism in intron 9 of glucokinase gene could have a role in predisposition to type 2 diabetes in women with gestational diabetes. In summary, our results suggest that, because of high costs and time-consuming methods of genetic studies, the investigations of glucokinase gene mutations should be concentrated in women with gestational diabetes without clinical and biochemical features of insulin resistance, but with family history of diabetes in two generations.