A sure sign of how insensitive and inappropriate a person is: when they begin to criticize a pregnant woman's weight. I'm sorry anyone is making you feel bad about your weight gain. What matters is what your doctor, a medical expert, says about your weight. If he says your weight gain is not alarming and within the healthy range, then that's that.
If you have gd, it's how your body processes the sugar - not a single thing to do with who you are or how you're taking care of your baby.