Now 49, the disease is catching up with him. His left leg was amputated below the knee in July 2013 after years of infections in his foot.
Shortly after the amputation, Johnston learned the health of his kidneys and pancreas was poor, and he may need transplants. Those transplants could occur at London Health Sciences Centre sometime in the next year.
If he receives the transplants, it will mean for the first time in his adult life, Johnston will no longer be insulin dependent.
To cover the roughly $7,000 it will cost him to stay in London after the operation — he'll need to remain there for about a month — his family and friends are organizing a Sept. 28 fundraiser.
Johnston, who worked for years at youth group homes before retiring because of health problems, said his illness has taken its toll on his finances.
The married father of an eight-year-old son admits the fundraiser will definitely help him cope.
“At the beginning, I was so-so, because I really don't like asking for help,” Johnston said, adding that he plans to pay forward any assistance he receives to other people.
Serving others is a way of life for Johnston, who has been a regular fixture at the Blue Door Soup Kitchen for the past four years, where he's been the kitchen manager and currently takes care of public relations.
“It's a rewarding situation,” he said.
“No matter what happens to yourself, it makes you stronger, because you always know there's a lot of people worse off out there then you are.
“It's nice at the end of the day you know you've served 220 or 250 people, and they've got a smile on their face, and you've just made their day, too.”
Although he has a hard road ahead, Johnston said he plans to face it head-on.
“You've only got two choices, right?” he said. “Fight it or roll up in the corner and quit. I'm not a quitter, so I've got no choice.”
The fundraiser — a dinner and live auction of donated items starting at 4 p.m. Sept. 28 at the Caruso Club's upper hall — is being organized by Johnston's sister, Erica Vaillancourt.
She said her brother works hard and cares about others. Now it's his turn to be on the receiving end of help.
Tickets to the “Dinner of Life” event, which cost $20 each, are available at Gloria's Restaurant, Laurentian Chrysler, the Ukrainian Credit Union and by phoning Vaillancourt at 705-918-1247.
Those who can't attend the dinner, but are still interested in making a donation, can make a deposit to account 625-822-100 at the Ukrainian Credit Union.