For 27 years, Sarah Breidenbach had a foolproof way of knowing when her blood sugar level was dangerously low.

Diagnosed with Type 1 diabetes as a child, she could spot the early warning signs — feeling shaky and anxious.

Then one night, her internal detection system failed. While sleeping, her blood sugar level plummeted, causing a violent seizure that sent her to the hospital. Her body recovered, but her inner monitor did not.

Over the next 18 months, paramedics made 178 trips to her home.

That's when her doctor prescribed an unusual tool to help manage her diabetes: a dog.

Enter Moxie, a 5-year-old service dog who sits at her St. Paul owner's side around the clock. The black Labrador can tell when Breidenbach's blood sugar is too high or too low — just by smelling her breath.

While still rare, diabetes alert dogs are an emerging segment in the larger service dog industry, which for decades has helped people manage such health issues as blindness, hearing impairment and autism. Can Do Canines, a training organization in New Hope, estimates that there are 150 diabetes alert dogs nationwide. Earlier this summer, the group hosted a conference that drew dog trainers from around the world.

"We can't train as many dogs as we want or as many as are needed," said Alan Peters, founder of Can Do Canines. Other local trainers include Pawsitive Perspectives Assistance Dogs in Savage and Scent Angels in Eden Prairie.

Using her powerful sniffer, Moxie is able to detect a distinct odor brought on by changes in her owner's blood sugar. When she smells it, the dog goes into alert mode. She jumps, she whines loudly, she paces and stares directly into Breidenbach's eyes until her owner relents and checks her blood sugar.

"It's crazy what they can do," Breidenbach said of alert dogs like Moxie. "I lost that intuition when I had that insulin reaction, and somehow she's got it now."

Dogs show promise, limits

An estimated 23.6 million Americans, or 7.8 percent of the population, have diabetes. Of that number, 10 percent have Type 1 diabetes — the most severe kind. Those who have had the disease for decades can develop "hypoglycemia unawareness," or the inability to tell when their blood sugar is rapidly dropping, doctors say.

There are electronic monitors to help keep tabs on blood sugar levels. But many diabetics with hypoglycemia unawareness report that their monitors can be late in alerting them. The dogs, they say, let them know very early.

Peters was moved to train diabetes-detecting dogs after a conversation he had that still haunts him. In 1994, he was speaking with a deaf woman with Type 1 diabetes who asked him if her hearing dog could be trained to help her monitor her blood sugar. Peters told the Minneapolis woman he couldn't help her. He learned later that her blood sugar dropped suddenly one night, causing a grave insulin episode. She died in her sleep.

Dr. Melena Bellin, a pediatric endocrinologist at the University of Minnesota who studies diabetes, said that while the dogs show promise, there is no scientific evidence yet on their effectiveness. She cautioned against owners relying solely on the dogs as their monitoring tool.

"It is not a substitute for checking blood sugar," she said.

Bellin is currently working with Can Do Canines and diabetics with alert dogs to study the issue. So far, she said, the dogs appear to be alerting their diabetic owners when their blood sugar was low or dropping fast.

The making of an alert dog

Training a dog to do this kind of work takes time and the right animal.

"The whole process is a two-year process if we start with one of our own puppies," Peters said. "We start molding the dogs just shortly after they're born to tolerate different noises and distractions so they're used to being out in public. These dogs in particular have to be with the person all the time, because they have to alert the person right on time."

In training the dogs, Peters explained, instructors teach the animals to recognize a particular scent from the breath of a diabetic with low blood sugar. "We don't know exactly what that [smell] is," he said. "There's a chemical change — and a certain scent happens."

When diabetics' blood sugar level drops below 80, they enter the danger zone. Trainers capture that low blood sugar-scent in a piece of gauze. The gauze is then placed in a plastic bag and kept in a freezer. During training sessions, the gauze is presented to the dogs so they can begin to recognize the smell. The average dog's nose is tens of thousands of times more sensitive to odors than a human's.

Since 2003, Can Do Canines has trained 28 dogs to alert diabetic patients. Right now, there are 21 people on a waiting list for alert dogs.

One recent summer morning at Breidenbach's home, Moxie, ever vigilant, sniffed out a problem early.

Breidenbach was sitting on a couch, with Moxie lying quietly on the floor a few feet away. The dog suddenly raised her head, got up and jumped on the couch, placing her paws on Breidenbach's chest and staring. Then Moxie began to whimper loudly, prompting Breidenbach to get up and walk to the kitchen to check her blood sugar level. Turns out it was high. Moxie followed her, eyes fixed on Breidenbach the whole time.

Breidenbach needed insulin.

After giving herself an injection, she rewarded Moxie with a pat on the head.

Having the dog, she said, has given her and her family peace of mind.

"I don't think about it anymore," she said, "whereas before I was constantly worried."

Since Moxie's arrival, there have been no more paramedic visits to her home.