Pre-ride fuel

I mountain bike 3-4 times per week, usually for 2-3 hours at a time (medium plus pace). I have been noticing that my Dexcom alarm goes off often after about 40 minutes into the ride.

I am thinking that I can minimize this, or reduce the chances of this with a pre-ride snack that will provide both a short term boost, and a sustained delivery of carbs…


If you ride early in the day you should replenish glycogen stores. Not critical, but useful if you go long.

For any ride over 90 minutes you can do the following, assuming T1 and pump.

Eat 3 hours before the ride. Bolus for the carbs with the intent of a 130 to 160 BG level at ride start. At least three hours so the insulin clears your system.

Reduce basal 25-50%.

Consume 30-45 grams carbs (gels with maltodextrin or drink is best) every 45 minutes. Don’t bolus.

Immediately post ride eat 30 45 grams and 50 protein. Bolus at 2/3 to 3/4 regular rate.

This will work for aerobic exercise 90 minutes to 9 hours or more.

Proven for diabetic endurance athletes. The 90 minute threshold is important.

I should have added that I don’t use a pump. I do use a CGM. I take novalog and lantus.

Sorry - I shouldn’t assume everyone uses a pump. A pump SERIOUSLY helps manage insulin and carb during exercise. And cycling over 90 minutes takes some careful management if you are putting out…

Try the Book “The Diabetic Athlete” if you want more insight. There are examples of how different types of sports/athletes manage their insulin/carb game - including mountain bikers.