If i am only hyperglycemic should i move onto insulin or continue taking metformin?

Depends: Controlling blood sugars aggressively during pregnancy does have a positive impact on the baby. Generally the levels of blood glucose that we want in pregnancy are much lower than what is sought in nonpregnant individuals. Generally your fastings should be around 90 and your one hour post meal glucose should be under 140 at least but ideally lower. You need to move quickly to control your sugar.

It depends: There is no easy answer. Treating hyperglycemia is a complex process involving education, diet, exercise and medication. Most likely a combination of oral medications would be adequate for now -- but Insulin may be needed now or in the future. Consult with your physician.