Aih, don't worry, insulin for GDM doesn't automatically mean c-section, okay! A few of my mum friends were on insulin jugak and managed normal delivery fine. Really depends on how your blood sugar control goes and what your doctor sees closer to your due date, they'll monitor you closely lah. Best to chat with your doc about your birth plan and what they're seeing; every pregnancy is different. You're doing great by taking care of it now!