February 2012 Inside research file
Mapping the link between blood sugar and location By Mallory O’Brien Sean Doherty holds up his BlackBerry for display. “Everyone has one of these nowadays,” he says, referring to the proliferation of smartphones in the wireless market. The professor of Geography and Environmental Studies is interested in harnessing the power and ubiquity of smartphones to make the lives of diabetes patients a little easier. Currently, he’s using the technology to research the relationship between a patient’s location and his or her blood glucose level. Diabetes, a group of diseases that cause dangerously high levels of blood glucose (sugar), affects nearly 200 million people around the world. Type 2 Diabetes, especially prevalent in North America, is often associated with lifestyle factors such as sedentary behaviour and poor nutrition. Therefore, management of the disease relies heavily on dietary and lifestyle management in addition to blood glucose monitoring. “However, the day-to-day human–environment interactions and real-life activities that cause an individual’s blood glucose to fluctuate remain relatively unexplored because of data collection challenges,” says Doherty. Traditionally, blood-glucose variation is monitored over time. Glucose levels go up and down depending on the time of day and the daily activities that coincide with it, such as when a patient eats or exercises. Rehab doctors will discuss with patients how to manage their glucose levels by recommending when they eat, exercise and prick their finger to ensure their levels are within a safe range. They also use this
information to make general recommendations for broader populations of diabetes patients. “One of the biggest complaints from the medical field that I read about is getting individual information from people about their daily lifestyle and what they’re doing,” says Doherty. “It’s expensive to get. And it’s difficult for patients to tell rehab doctors ‘this is how much exercise I’m getting.’ It’s difficult for someone to reveal that he or she isn’t walking enough or is eating too much.” Doherty, whose previous research involved using Global Positioning System (GPS) software to analyze the flow of urban traffic, discovered he could explore glucose variation over space in addition to time. But he had to overcome a few obstacles first. Asking patients to record or recall their own data is inconvenient and inaccurate. Asking them to prick their finger every hour or more is not only problematic, but also painful. To overcome those challenges, Doherty designed a collection system using the GPS software on BlackBerries and a blood-glucose monitor that takes readings every five minutes — without the need to prick fingers. During a pilot study of 40 diabetes patients, Doherty, who partnered with the Toronto Rehabilitation Institute for the study, used the devices to monitor patients for a 72-hour period. The GPS continually gathered information about a patient’s daily travels while the blood glucose monitor measured the patient’s glucose levels. Doherty also monitored a number of other health-related factors through food diaries and interviews. “Sometimes you have to fill in the gaps when the GPS goes out,” he says. “If I see a patient
Photo: Mallory O’Brien
Sean Doherty uses modern technology to help diabetes patients better manage the disease
Sean Doherty uses BlackBerries and a blood-glucose monitor to study how location affects the blood-sugar level of patients.
go into a building and then see him leave, it’s a safe assumption he stayed in the building, but there’s still a chance he left the GPS in the building and went for a run — and people will do that. Human subjects do funny things sometimes.” Doherty was able to use the information he gathered to provide comprehensive data collection that was largely non-invasive for patients and required little input. He used tailored software to generate blood-glucose maps that could be read by health-care practitioners to better detect lifestyle risks in diabetes patients.
This map shows a patient’s blood glucose levels every five minutes, mapped out over a three-day period. The larger pies show the varying distribution of values at different destinations, especially at the upper left location. The changing values along trips is also noticeable. The data has been carefully modified to protect patient identity.
Analysis of the data revealed that location and distance from home were significantly correlated with blood-glucose variation in patients, although the effect differed greatly. Some patients experienced higherthan-normal levels away from home, while others experienced lowerthan-normal levels. Most subjects had at least two major anchor locations in their lives, combined with a variety of other activity locations at varying distances from home, many associated with distinct low or high blood glucose values. Doherty speculates that a number of factors could cause these effects, including: • Breaks in routine • The kinds of foods patients are eating at specific locations • An increased or decreased level of physical activity at specific locations • Stress from being in or out of the home • Long trips “We know that it is all those factors and we know that food and exercise are still related to bloodglucose levels,” he says. “But the takeaway message is that location matters to your health, as does your distance from home, and we can use this new perspective to improve patient health and care.” In the future, Doherty believes patients and caregivers will benefit from highly individualized monitoring and visualization tools that identify problematic locations in patients’ lives. Health-care practitioners will be able to recommend important times or areas for patients to pay special attention to their blood glucose levels.
He also believes this will ease the strain on Canada’s health-care system. According to the Canadian Diabetes Foundation, the disease cost Canada $11.7 billion in 2010. Eighty per cent of the cost was due to complications, and the number of complications and emergencies that arise from diabetes can be lessened with better monitoring and care. Doherty speculates that drug companies and manufacturers might be interested in new recommendations concerning when patients should check their glucose levels. He is excited about conducting additional studies and providing new recommendations.” “It could be as simple as telling a patient: you’ve taken a long trip so you should consider pricking your finger, or you’re at a location far from home or you’ve broken your routine significantly,” says Doherty. “Maybe one day we can even develop an automated earlywarning system, like your BlackBerry buzzes if it notices you’ve been travelling for a number of hours.” Doherty has also applied his research and technology to other health-care initiatives, including monitoring the elderly so they can live in their homes longer, and monitoring children with disabilities to improve their quality of life. “Diabetes, obesity and our growing elderly population are three of the biggest urban lifestylerelated issues the Canadian health care industry is currently facing,” he says. “They all contribute significantly to costs and wait times in hospitals — the more we can people out of hospitals, the better for everyone.” 7