So invested was the single mother of two that when Denise was laid off in 2012 after 20-plus years working at a shipyard, she refused to take another job that would cause her to work Friday nights during football season.
"I cannot tell him, 'Mama's got to work tonight, so I can't see you play,' " she told The Salt Lake Tribune by phone Thursday.
She most likely won't miss much this season. Isom is one of six quarterbacks vying for reps, and most of those have so far gone to the top two, Travis Wilson and Kendal Thompson. But the 6-foot-3, 235-pound Isom says he only has to look to the example of his mom, who now works at a middle school and part-time at CVS, to stay motivated.
"I've always wanted to be like my mom," Isom said. "My mom is my idol. She raised us and everything, and watching that was incredible."
Coaches say the freshman has done everything they've asked, including losing more than 20 pounds since leading Destrehan High School to the 5A state semifinals as a 255-pound senior.
"He's a really humble kid," said Utah quarterbacks coach Aaron Roderick. "He just really is an awesome guy. You can't say enough about how hard he's worked to get here in the first place."
As a high school senior he passed for more than 2,600 yards and 33 touchdowns, rushed for more than 500 yards and nine more scores, and was named homecoming king. Destrehan quarterbacks coach Daniel Luquet told the Times-Picayune in February that Donovan would have had his pick of colleges had he wanted to play tight end. He didn't, though. He wanted to be a quarterback, and Utah offered him that opportunity.
Mom's initial response was "Ooookaay," she says, but on a visit to Utah she witnessed a family atmosphere reminiscent of the one at Destrehan High. Even if she'd have to miss a few games, she felt her son would be taken care of.
Donovan has nice things to say about every quarterback on Utah's roster, and he's just trying to soak up knowledge from each of them, he said.
"He fits right in with the group," Roderick said. "He's a good athlete. He's got a good arm really good arm and we're trying to work on his touch passes."
Like Wilson, he's tall and mobile. And he's always had a cannon, Denise says. She knew he was unique when, as a freshman on JV, he threw a ball to midfield from his own end zone.
"The people in the stands were talking, not realizing who Donovan Isom's mom was, and I was listening to their comments. ... 'This boy's going to be something special.' "
Denise said strangers approach her and compliment her on the manners of Donovan and his younger sister, who always say "No, ma'am" and "Yes, sir." He called her at the stroke of midnight Wednesday to wish her a happy birthday.
"That makes me feel good, because doing this as a single parent ... it's not an easy job," she said.
She's thankful that his full scholarship will make things much easier.
There is one hardship caused by Isom's move to Utah, however.
Donovan, who is "always hungry," was her "food-taster."
"No matter what I was cooking, he'd tell me, 'Ma, it's good the way it is,' or 'Ma, it needs a little bit more seasoning.' "
Now, she says with a laugh, she's going to have to ship her meals to Utah for him to test.