Alright, I know I’m going to get a lot of rolly-eyes for this one, but it was what happened to my Goddaughter at 11 going on 12, so I have to share just to make myself feel like I said it.
Laurie was exactly like you describe in your OP. She was argumentative, whiney, generally all around bratty and just unpleasant. She was a screamer and a thrower of things. Mostly around her mother. Who really didn’t know how to handle her except alternately give in or scream back at her. She was fine around me or other people if mom wasn’t around. (Homeschooled, so didn’t have an outside school environment to compare it to.) We were all certain her behavior was because her mother didn’t give her consistent limits.
She was also a very tall, thin girl, with a lifelong love of carbohydrates. She’d eat an entire loaf of bread for dinner and nothing else, if you didn’t watch her plate closely.
One dreadful weekend, after attending no less than 3 birthday parties, Laurie got the flu. She was the type to curl up and get very, very quiet when she was sick. Mom (an ER nurse) made sure she was getting fluids and pretty much left her alone for the first two days. By the third day, I was getting panicked phone calls from mom. Laurie was even less responsive than usual, and was drinking all the root beer she could get her hands on, but wouldn’t eat or drink anything else and was, in mom’s words “suddenly looking as thin as a concentration camp photograph”.
That night, they admitted Laurie into the ER in a diabetic coma. Her blood sugar was 785.
Three days later, she came out of it, and the long learning-to-live-with-diabetes process began. She is a completely different person. She is charming and polite and when she has an issue she can talk about it without screeching, and it’s just simply amazing. The doctors told us her behavior problems were probably linked to inconsisted blood sugar levels she’d been having for years.
And, once in a while, the “Old Laurie” returns. Sure enough, it’s when her blood sugar dips below 60 or above 200.
So, while the odds are overwhelmingly against it, I do think of Laurie’s story when I read your OP. So I’m just putting it out there. Do with it what you will.