Have you looked into using very small amounts of carb throughout your workout, rather than a big slug of something every 30-45 minutes? As someone with Type 1 diabetes, I have the best results keeping my blood glucose stable by using small sips of sports drink every 5-10 minutes, rather than slurping down a gel and then dealing with ensuing spike. My drink preference is Vitalyte, as it's fairly low in carbs compared to many out there, but still provides some necessary carbs and is easy on the stomach.

Can you experiment a little between now and then?

Good luck!