People with insulin-dependent diabetes can suffer from dramatic swings in their levels of blood glucose. Often, they can't tell when they're about to have a severe drop in blood sugar that could cause them to collapse and even die. Sometimes, they aren't aware when their blood sugar has dropped to dangerous lows. Not knowing when or where they might experience dangerous drops in blood sugar can make it difficult for diabetic people to live full, active lives.
Over the years, some diabetic people and those who work with them have noticed that dogs seem to be able to sense when blood-sugar levels are low, and sometimes even when those levels are about to drop dangerously.
The answer seems to be that a dog's super-sensitive nose can smell chemical changes in a person's breath and skin that are caused by rapid changes in blood sugar levels. The dog's sense of smell acts much like the breath detector used to check drivers for alcohol in the blood, only it's more sensitive.
It takes training to take advantage of this canine ability. Since 2004, an organization called Dogs for Diabetics (D4D) has been training medical assistance dogs specifically to detect dangerous blood-sugar changes. The dogs learn signals to alert their human companions, or the parents of children with diabetes. The training is expensive, and so are the assistance dogs.
Not everyone with diabetes needs an assistance dog. They are most useful for people who have frequent and unpredictable drops in blood sugar. They can be a great help for parents monitoring young children, and for young adults leaving home for the first time [source: D4D].