For people with diabetes who take insulin, the risk of losing consciousness from low blood sugar is a constant fear. Devices called continuous glucose monitors (CGMs) can alert wearers to dropping levels, but not everyone has access to them. And even among those who do, some prefer a furrier and friendlier alert option: a service dog with special training to alert owners when their blood sugar reaches dangerously low levels. These dogs are trained in a variety of ways, and although they receive certification, there is no universally accepted test to ensure their competence. Fully trained dogs can cost in the $20,000 range and typically aren't covered by insurance, although some nonprofit organizations can help offset the cost.