Alyssa, you cannot depend on "free" feeding to manage a hypoglycemic pet. You must monitor the amount they eat throughout the day. If you want to sit out food for "free" feeding, you need to weigh the food on an accurate gram scale and then weigh it frequently throughout the day to determine if she is eating anything. If she is not eating, then you need to make her eat by giving her something you know she will not refuse to eat. The best managment technique is to feed small but scheduled meals at least three times a day and observe your dog actually eating them. With my cat, I fed him after I got home at 9am, after I got up from sleeping at 5 PM, and left him precisely weighed dry food overnight (which I again weighed in the morning after I got home.) I also left him with a wet meal in a feeding dish which had a timer on it, set to open at 1am while I was at work. If I was off, I fed him his meal myself before I went to bed for a nap at between one and three in the morning (I worked night shift).
You need to see the dog eat, know they have adequate intake of calories and, if they do not eat, then entice them to take in calories. If your dog is anything like my cat, Whip, she will take advantage of your concern and usually dupe you into giving her wet food as a bribe for good eating!
When I was at home, I had to check on Whip every two hours to assess if he was showing any signs of hypoglycemia. Whip was diabetic and got insulin injections every morning. I also kept sweetened condensed milk available for him, as I could always get him to lick up an ounce or two of it to ward off low blood sugar if I felt he wasn't eating well. Once I found him when I got home from work, passed out on the floor and I gave him ten cc of 50% glucose IV, and rushed him to the vet. Old age did not go well with Whip and his insulin stopped working well. I found him dead on the floor at age 12; whether it was from hypo- or hyper-glycemia I will never know.
A hypoglycemic pet is very difficult to manage unless you are extremely dedicated to making sure they eat on a regular basis.