Adapted from March 2008 issue of Diabetes Forecast published by the American Diabetes Association ©2008.

Devin Grayson’s world was shrinking. The 36-year-old California comic-book author and video game writer had been diagnosed with type 1 diabetes when she was 15, and like many people with insulin-dependent diabetes, she suffered wild swings in her blood glucose. Over time, she’d also developed hypoglycemia unawareness, the inability to recognize symptoms of severe glucose lows. “One night I woke up and my blood sugar was 17,” she recalls. “It’s amazing I woke up at all and didn’t die in my sleep.”

By the summer of 2005, Grayson was restricting her activities because of her fear of hypoglycemic episodes. She gave up many of her favorite pursuits, like hiking in the redwoods north of San Francisco, and became reluctant to go out alone. She even moved into a house with friends because she worried that her diabetes made it dangerous to live alone any longer. And still she felt trapped. “There’s a real psychic burden attached to diabetes,” she says. “You never get a break. Every meal, every day, you have to monitor. It’s lonely. There are days when you would do anything just to have a weekend off.”

Then Grayson met Cody, and everything changed. It was an Internet hook-up, of sorts: Online, Grayson had discovered Dogs for Diabetics, a Concord, Calif.–based organization that trains dogs to respond to serious blood glucose drops in humans. She registered for classes in the summer of 2005, and in six months she was teamed up with Cody, a male Golden Retriever. Not only has Cody saved Grayson’s life, he’s given her a life to enjoy, she says: “For the first time since I was diagnosed, I feel this enormous burden has been lifted. I’m not alone with it anymore.”

Assistance dogs, such as guide dogs for blind people, dogs that “hear” for the hearing impaired, or dogs that retrieve items for the wheelchair-bound, have been helping humans for decades. But Cody is part of a new trend in which dogs are trained to identify the onset of hypoglycemia in people with insulin-dependent diabetes.For the dogs, it’s a game. Once they alert, they receive their treat, plus lots of positive inforcement from their owners. But for the humans they live with, the results are nothing short of miraculous.

And yet science tells us nothing about whether dogs can really do this. Or how: “We believe the dogs are picking up on scents that are created by chemical changes going on in the person’s body before we humans see the actual symptoms of the illness,” says Darlene Sullivan, executive director of Canine Partners for Life. But the scent has not been identified. In fact, the first academic study to evaluate how well dogs detect hypoglycemia is being done by Deborah Wells, MD, at Queens University in Belfast, Northern Ireland. If she verifies that dogs can alert to blood glucose drops, her next project will be to identify the sensory cue the dogs are reacting to.

Part of what is so uncanny about these dogs is their reliability: Trainers say they are right 90 percent of the time. They also seem to have a skill that no test kit or piece of machinery offers: the ability to sense a dangerous drop in blood glucose before the drop occurs. Some dogs become so good at sensing low and high blood glucose that they “diagnose” people around them. At Grayson’s office, for example, a coworker mentioned that Cody had been anxiously pawing the woman’s knee. “Wait a minute,” Grayson said, and went to get her glucose monitor. When she checked the woman, her blood glucose was 180. She was later diagnosed with type 2 diabetes.

To read the rest of the article, see the March issue of Diabetes Forecast.