First of all, let me preface that I am not a medical professional and can not give medical advice. I just tell you what I do and what works for me may or may not work for someone else as we are all different. Also, what works for me a lot of the time can be drastically different and not work sometimes. Diabetes care varies all the time, so expect that how you manage your diabetes will vary considerably and will be different than how someone else manages their care. It is important to work closely with your endo, nutritionalist and check your blood sugar frequently, Your cgm, while not the one time perfect solution, will help tremendously with your blood sugar trends and alerts and adjustments.
I generally snack while exercising to keep me from dropping too low during the exercise. My cgm is a big help as I can set the alarm to go off at a higher number and during rapid decreases, which helps me manage eating. During strenous exercise, I can easily burn up 150-180g of carbs and still go low during exercise and in the night. Through trial and error, I have discovered baby food in pouches which have a screw top and I can easily squirt them in my mouth on the run. They have fruit smoothies that are made of real fruit and taste great. I much prefer real fruit nutrients and electrolights to dextrose cubes. Also, I found some individually wrapped prunes that are easy to pull out of my pocket during a run. Be sure to always carry snacks with you and more than you think you will need. I rarely use them, but always have the dextrose cubes in my pack as a backup.
I also suggest exercising with friends who can recognize low symptoms, listen for your cgm alerts and help you treat the lows. There have been a few times where I have dropped very rapidly to the point of not being able to recognize that I needed to eat something and my friends has been there to make me eat and get me home. I have a GlucaGen pen and my friends know how and when to use it for emergencies. Fortunately, I haven’t had to use it.
After excercise, I can and do go low. As I have had several episodes of severe lows where it has been difficult to get to the kitchen for a snack, I keep snacks on my bedside table. Again, the fruit baby foods are easy to eat and fast acting. I look at my cgm trend before going to bed and if I am on the lower end of my range eat an additional snack before going to bed.
Again, check your blood sugar frequently and expect that exercise will be something that you will need to account for. I generally, cut my fast acting insulin doses significantly before and after exercise. Also, I may reduce my long acting insulin. It can be distressing as it changes all the time. Diabetes management is certainly not an exact science.
Discuss with your doctor and nutritionalist for your specific needs and their recommendations. I wish you the best.