Welcome to HCM,
After going through your history if you have history and Gestational Diabetes
you must take care to control with insulin
according to blood sugar level and your diet.
In full term pregnancy
your doctor gives steroids
injection for maturity of lungs,but that will not harm your baby but your blood sugar must be in desirable range an dcan be managed by proper insulin injection and repeated measurement of your blood sugar level.
Some time in diabetes size of baby is big and a pre planned surgery may be reason for giving steroid injection.
You can discuss with your treating physician for control of diabetes.
You should also take care of your blood sugar level even after delivery that you do not develop diabetes.