A tough illness shifted Lauren Dahlin's life into high gear.

In 2017, Lauren Dahlin came down with what she thought was the flu—fatigue, a nagging cough, nausea. Dahlin, now 28 and living in Hyattsville, Maryland, visited a few doctors, who all chalked it up to a persistent virus and advised her to rest.

But rest did little to relieve Dahlin of her symptoms. And when the CrossFit devotee and weight room regular couldn’t catch her breath while simply walking down the street, she took herself to the emergency room. Just 30 minutes later, doctors there diagnosed her with Type 1 diabetes, meaning her pancreas produces little or no insulin. Her blood sugar level was so high for so long that her blood was no longer efficiently exchanging oxygen. Dahlin was admitted to intensive care with severe diabetic ketoacidosis, where she stayed for five days.

Suddenly slapped with the responsibility of managing a chronic illness, Dahlin learned how to carefully monitor her blood sugar levels and use an insulin pump from her hospital bed. To deal with this, she could have streamlined her day-to-day life and opted for a simpler, less stressful schedule. Instead, just months later, Dahlin entered a PhD program at the University of Maryland’s Smith School of Business–and became a triathlete. Not only that, she’s now one of the fastest women with Type 1 diabetes to complete an Ironman.

“After my diagnosis, I was afraid I would be limited for the rest of my life,” says Dahlin, who had only competed in a couple of sprint triathlons “for fun” prior to her diagnosis. “But there’s this whole community of incredible people who choose to live a life of endurance sports and don’t see diabetes as a limitation.”

This community includes people like Dahlin’s coach, Cliff Scherb, a fellow Type 1 diabetic and founder of TriStar Athletes based in Norwalk, Connecticut. Aside from offering standard coaching, he works with Dahlin to carefully dial in her nutrition and insulin delivery during training and racing.