Gestational diabetes: how can I lower fasting blood sugar?

I was diagnosed with GD and I've been monitoring my blood sugar for a week now and my day time ones are all normal for the most part unless I ate really bad or didn't do any physical activity after my meal. But I consistently have high fasting blood sugar and I can't figure out a way to lower that.

I'm looking for suggestions on what I can do.

My average fasting blood sugar is between 97-100. I was told it needs to be less than 90. Right now we're trying to figure out if I can manage with just diet and exercise. If I can't get it figured out my doctor will put me on medicine or insulin.

Any and all help is welcomed.

Thank you in advance