Pregnant women with gestational diabetes who are treated with insulin and their daily insulin dose is 30 IU or more will be randomized into two groups. Active treatment group will recieve insulin-glucose-infusion during labour. In the observational group, blood glucose level during labour will be monitored and insulin-glucose-infusion is started only if needed. The hypothesis is that there will not be a difference in rate of hypoglycemia between the two groups and that the proportion of observational group participants that need infusion is low.