A small pink device tethered to her waist does what her pancreas quit doing: It makes insulin.
"It's my magic juice," said the 10-year-old Marysville girl.
On her wrist, a pink silicone bracelet with a metal emblem functions as a medical alert ID.
Mary has Type 1 diabetes.
The pager-shaped insulin pump is by her side even more than her fraternal twin sister, Esther, who doesn't have the disease.
Mary and the pump have a symbiotic relationship. She inputs meal data, and it measures and dispenses insulin.
The $7,000 machine is an alternative to multiple daily shots. Mary sizes up the cost this way: "I wear a used car on my waist."
Type 1 diabetes, an autoimmune disorder, is also known as juvenile diabetes because the onset is typically in childhood. Unlike Type 2 diabetes, it is not linked to obesity. There is no cure for the disease, and in Mary's case, as with many, there is no family history.
Mary, who is home-schooled with her siblings, does finger pokes before meals to get accurate glucose readings.
Diabetes care is 24/7. At night, while Mary sleeps, a machine monitors her levels and alarms her parents of dangerously lows or highs.
"She can go from sleep to coma," said her mom, Janette.
"I don't let it hold me back," Mary said.
Janette Key is trying to connect with other Snohomish County families with Type 1 diabetes for informal meet-ups at places like the YMCA, where she's a Zumba instructor.
The disease is a family effort that also involves Mary's dad, Chad, a Virginia Mason systems administrator, her sister Eleanor, 12, and brother Thomas, 14.
It all started on a family trip to Disneyland in November 2011.
Mary felt sluggish, not fired up by the wonder of it all. She guzzled water. She had to get out of line every 5 to 10 minutes to run to the bathroom.
Her parents chalked it up to the decadence of an L.A. vacation.
"You're eating ice cream for breakfast," Mary explained. "There's all this smog."
Her condition was manageable, so rather than seek medical care there they decided to brave the plane ride home. The last leg of the journey was the worst.
"Even when she walked a foot she'd get tired," Esther said. "It kind of looked like she was 90."
"My arms felt like sausages," Mary said.
They rushed from the Seattle airport to the Everett emergency room.
"A lady with a clipboard said, 'It looks like your daughter has Type 1 diabetes and will be insulin-dependent the rest of her life,'" Janette Key said.
Mary spent five days in Seattle Children's Hospital, where she and family members were trained about every aspect of diabetes.
"It gets easier as you go along," Mary said. "There's some learning curves, but that doesn't make it impossible. It can get frustrating. I get these days where it's, 'Why did it happen to me? Why did I get this?'"
It has its perks.
"When I'm low I get candy, and I don't have to share," Mary said. "I am happy and yet I'm not happy."
One time, a low level got her out of chores. "It happened while I was cleaning, so I got a break."
It hasn't cramped her style much. Mary takes off the pump when she swims and dances with it during her mom's Zumba classes. The worry factor limits sleep-overs with friends, but sharing a bedroom with a twin makes every night a slumber party anyway.
The home-school curriculum devised by the parents requires the children to write a book by the time they are 15.
Mary's already started writing hers about diabetes. "It's my story of how we got it," she said.
"We all got it," her dad agreed. "Absolutely. It changes every aspect of what we do. Simple things like going to dinner as a family, now we have to have nutritional information."
But, said her mom: "It doesn't define who she is. She isn't 'a diabetic.' She isn't 'a girl with diabetes.' She is Mary, a girl who has to deal with it."
Mary's twin also deals with it.
"I wish there was some way I could make a magical headband and put it on her and she wouldn't have diabetes anymore," Esther said.
Andrea Brown; 425-339-3443; firstname.lastname@example.org
Type 1 diabetes
Warning signs of Type 1 diabetes include: extreme thirst; frequent urination; drowsiness or lethargy; sugar in urine; sudden vision changes; increased appetite; sudden weight loss; fruity, sweet or winelike odor on breath; heavy, labored breathing; stupor; and unconsciousness.
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