A woman with type 1 diabetes can give birth to a healthy baby.
Most babies born to people with type 1 or type 2 diabetes do not have birth defects.
However there is some risk for people who are pregnant and have poor control of their diabetes. In this case, the chance of a baby to be born with birth defects is about 6% (1 in 16) to 10% (1 in 10). There is also an increased chance for stillbirth in women who have extremely poor control of their BGLs (particularly in the first trimester).
Reference: https://www.ncbi.nlm.nih.gov/books/NBK583003/