This patient support community is for questions related to juvenile diabetes including celiac disease, depression, diabetic complications, hyperglycemia / diabetic keto-acidosis, hypoglycemia, islet cell transplantation, nutritional issues, parenting a diabetic child, pregnancy, pump therapy, school issues, and teens with diabetes.
I wouldn't allow any coach to put his rules of discipline over my loved one's health needs.
I'd encourage you to insist that she be able to test/ be tested AND have her drinks nearby. Remind him that it is not a DRINK she needs; it's "medicine" if she's low.
IMO, with a pool full o' kids, he is incapable of monitoring her as diligently as she might need.
In light of the recent dangerous hypo experience with her, he might wll interpret her "non-response" as defiance and the potential risk is unthinkable to consider.
Perhaps you can talk with him privately to convince him that she needs her medical supplies with her. Period. If he's unwilling to bend, move up the chain of command or find another place for her training, one that IS safe for her.
Best wishes and good luck on this.