Insulin?

I just officially got diagnosed with gestational diabetes last week, 28 weeks. We’re doing a “test” week and I’m writing down all my numbers for fasting and 2 hours after eating a meal. My question is how do you know if you’ll be diet controlled or be put on insulin? So far my numbers have been pretty good but I’ve gone over 3-4 times with my 2 hour. Just wondering if this is good enough or if there’s a possibility of me needing to use insulin in the future or not.