"I have very little sensation on the bottom of my feet," explained Marc Fairman, who's type 1 diabetic.
Fairman will never take his feet for granted again. In 2012, he developed a foot ulcer that got out of control.
"I sought several opinions -- surgeons and podiatrists -- and several told me i would probably lose my foot," he said.
For 30 million Americans with diabetes, UCSF surgery professor Michael Conte said it's a very real danger.
"You can imagine if you had a pebble in your shoe, you'd take one step and stop," Conte said. "But if you don't have sensation, you're going to keep walking until you've created a hole in the bottom of your foot."
Fairman opted for months of grueling treatment, and managed to save his foot. Now, his doctor has him beta testing a new product for diabetic foot health: smart socks.
"I don't think i've ever worn white socks with dark pants before," Fairman said.
The socks are the brainchild of Ran Ma, who studied biomedical engineering at Johns-Hopkins University while working in a wound care clinic. She learned one of the earliest ways to spot a foot ulcer before it breaks through the skin is a "hot spot" on the bottom of the foot.
As the body tries to heal itself, the area around the wound becomes inflamed, causing a very localized spike in temperature. Doctors can pick it up with a large infrared thermometer by routinely testing six spots on the bottom of the foot -- and Ma's socks -- called Siren Diabetic Socks -- have invisible sensors woven into the fabric in precisely those six spots.
"When there is a significant temperature difference, you'll see a red spot," Ma said, pointing to the mobile app that shows a diagram of the patient's feet and also gives push alerts whenever the socks sense something out of the ordinary.
Though diabetic patients are told to check their feet every day, that can sometimes be tough.
"Many of these patients, not only do they not feel their feet well, but they also have problems with vision," Conte said. "They may not be able to inspect their feet easily."
Conte said though the socks haven't undergone clinical trials yet, they show promise as a useful tool for early warning -- especially for tech-savvy patients like Fairman, who showed us his new insulin pump, wirelessly linked to a continuous blood glucose monitor.
When they launch later this year, Siren socks will be sold by subscription: $20 a month for ten new pairs of socks a year. They're machine washable and dryable, and contain a small battery that never needs to be charged.
As for Fairman's fashion complaint, Ma says Siren is working on new colors and styles, including crew socks, knee high socks and ankle socks.