In the future wearable sensors could tell us much more than just how many steps we've taken or guess at how many calories we've burned each day. New research shows it wouldn't take much tweaking for activity trackers and other wearables to be able to also detect when we're getting sick.

A new study by researchers at the Stanford University School of Medicine says wearables that track heart rate, skin temperature, activity and other metrics could be able to detect when the body is fighting infection, inflammation and even insulin resistance.

The research involved almost 2 billion measurements from 60 study participants continuously wearing a suite of biosensors. Each participant also had periodic biological data collected from blood tests, their genetic expression and other measures.

"I was very impressed with all the data that was collected," said Eric Topol, MD, professor of genomics at the Scripps Research Institute, who was not involved in the study. "There's a lot here — a lot of sensors and a lot of different data on each person."

The study found that by establishing a baseline of "normal" measurements for a person and monitoring deviations from those norms via wearables, algorithms designed to pick up when that continuous stream of biological data diverges from regular patterns could help medical diagnoses and research.

The potential for this technology is perhaps best demonstrated by an experience that Stanford professor and geneticist Michael Snyder had while he was one of the 60 participants in the study.

Snyder was wearing the suite of sensors on a long international flight when his heart rate and blood oxygen levels did not return to normal after the flight, an event that typically disrupts their regular patterns. He suspected something might be up and sure enough, he went on to develop a fever and other symptoms of an illness.

Because Snyder had spent time two weeks earlier in a part of New England known for ticks that carry Lyme disease, he persuaded a doctor to prescribe him an antibiotic known to fight it. Later tests confirmed that the bacteria that causes Lyme disease was at fault.

"Wearables helped make the initial diagnosis," Snyder said.

Later analysis confirmed that the deviations he saw in heart rate and oxygen levels during his travel were abnormal.

Synder's case is just one of many intriguing ways wearables can help monitor health, including detecting early indications of conditions such as infection, autoimmune diseases, developing cardiovascular disease, diabetes or even cancer.

While the research is preliminary and the biosensor system requires further development and refinement, researchers see a future in which health can be monitored continuously rather than just at regular doctor's visits that may be separated by many months.

"We have more sensors on our cars than we have on human beings," says Snyder, who expects that equation will eventually flip, making individuals more aware and more in control of their own health.

The research was published January 12 in the journal PLOS Biology.