Eh, this is really something you need to ask your doctor or the nurse at your clinic, okay? Blood sugar levels for GDM are very specific to each mum, yours might be different from someone else's, so don't compare. Your doctor will tell you exactly what your target numbers should be and how to check them, especially since you're on insulin already. Go see them soon if you haven't discussed your targets clearly yet, yeah? Take care of yourself and baby!