WASHINGTON POST, PETULA DVORAK

When the White House called to invite Joshua Davis over, no one had to scramble to buy a suit. At 13, he’s already been at this for years.

“I was 4 and me and my parents were passing a law, a bill or whatever,” said Joshua, describing the first time he lobbied the Virginia legislature on behalf of thousands of kids like him who have Type 1 diabetes.

Dependent on insulin since he was diagnosed at 11 months old, he’s a kid who grew up explaining to his friends why he needed 10 shots a day, and why his fanny pack would beep. Then, he started explaining to lawmaking adults how the costs of his lifesaving medicine are tough on his middle-class family.

“I don’t actually remember it,” Joshua said, of his first appearance as an advocate. But he’ll never forget Tuesday.

He was serenaded by first lady Jill Biden for his 13th birthday (which was Monday), rode in the presidential motorcade and was introduced to the entire nation during the State of the Union address. His family dined in the White House (chicken for him and his big brother, crab cakes for parents Shannon and Brian).

At 4, at 7 and at 12 he asked lawmakers to fix rules that make life even harder for kids like him; explaining to adults that students who aren’t allowed to carry their insulin or snacks with them might have to make five, 10 or 12 trips a day to the school nurse.

“I usually miss math, which is one of my favorite subjects,” he said, in a public appearance in 2017, in a smaller version of this week’s boy suit, talking about a pump that acts as an artificial pancreas. Math is right after recess. After running around on the playground, his blood sugar always dropped and he’d have to go to the nurse, have a juice box or a snack, wait 15 minutes and test again.

He also helped explain why, during fire drills and the increasing amount of active shooter drills and school lockdowns, being separated from his medication could be life-threatening.

Last month, he introduced President Biden at an event on prescription drug costs at Germanna Community College in Culpeper, Va.

“My entire life, this is all I have known,” he said. “And, until there is a cure, all I will know.”

Of course, the White House invited him over after he delivered that gut-punch line.

“There were so many people,” Joshua said from the back seat of his parents’ car, as they drove back home to Midlothian, a suburb of Richmond that was originally settled as a coal town. “There were at least 10 cameras on me, and I was like, ‘Oh, my God! What am I going to do? I’m going to die!’ ”

But mom prepared him well.

“She told me to watch Dr. Biden and do everything that she does,” Joshua said. “To stand when she stands. To clap when she claps. It was overwhelming.”

Then on Wednesday, as they toured the sights of the nation’s capital, he kept getting stopped, like a major celebrity.

“They kept saying: ‘Hey! You’re that kid!’ ” Joshua said, without a hint of celebrity ennui. And his brother Jackson, 16, acted as his body man, organizing the fans for photos.

Being a goalie on his local lacrosse team also prepared him for the pressure.

“When you’re out in the spotlight, it’s just like if someone’s charging up at you on the field with the ball,” he said. “It’s energizing and terrifying. And if you pass the ball, it’s amazing. It’s like if you delivered the speech.”

Joshua’s appearance at the U.S. Capitol was part of the president’s campaign to lower prescription drug costs.

“We pay more for the same drug produced by the same company in America than any other country in the world. Just look at insulin. One in 10 Americans has diabetes. In Virginia, I met a 13-year-old boy, the handsome young man standing up there, Joshua Davis,” Biden said during his State of the Union address on Tuesday.

“He and his dad both have Type 1 diabetes, which means they need insulin every single day. Insulin costs about $10 a vial to make. That’s what it costs the pharmaceutical company.

“But drug companies charge families like Joshua and his dad up to 30 times that amount,” Biden said. The Davis family spends $5,000 to $7,000 a year on diabetes supplies, said Joshua’s mom, Shannon Davis.

“It’s life support. It’s not a choice,” she said. “It’s required to live.”

Managing it may be part of what’s made Joshua so mature and poised, said Rep. Abigail Spanberger (D-Va.), who has been working with the Davis family for years.

“He’s had to be more mature than his other friends,” Spanberger said, something she realized when Joshua explained to her everything that goes into monitoring his own body and responding to it.

So they told their representative about the decisions and sacrifices they have to make every time they buy their prescription drugs. Shannon is a substitute teacher and Brian is a speech pathologist — they’re hard-working Americans, but not part of the lawyer and lobbying crowd.

“We’re facing higher prices at the gas pumps, supply chain issues. It’s been a tough two years for families,” Spanberger said. “And this is one more added difficulty for families, one more pain point.”

After dinner at the White House, Shannon rode with Joshua in the motorcade while Brian and Jackson stayed behind. They wandered the East Wing and then watched the speech in the “plush, red velvet” White House movie room.

“They have presidential M&Ms!” Brian marveled.

Shannon said it was a “once-in-a-lifetime” experience. What if Joshua has a career in Congress, or the White House, even — I asked.

“I’m an advocate, not a politician,” Joshua corrected me. He’s interested in engineering or technology.

Jackson, however, may be the one to bring the Davises back to Capitol Hill. His plan is to serve in the military, then run for Congress.

The adventure was “a really great experience, really eye-opening,” Jackson said. “How someone as small as a family of four from Midlothian, Virginia, can really impact the lives of so many people across the country.”

Joshua returns to Swift Creek Middle School this week, where none of his seventh-grade friends or teachers knew he’d be a celebrity by the end of the week.

Too bad big brother won’t be around to manage the selfie-seeking fans.