During a game in her junior year, Ithaca College field hockey player Sarah Gibble knew something wasn't right.
She continued to play through her senior year, dealing with the challenges faced by thousands of athletes with diabetes.
While exercise is beneficial for diabetics, helping to stave off complications and control blood sugar, it takes planning and care to participate safely.
Former NBA center Chris Dudley, golfers Scott Verplank and Kelli Kuehne, Olympic swimmer Gary Hall Jr.
Around 800,000 people have type 1, or juvenile, diabetes in which the pancreas produces none of the blood-sugar regulating insulin.
Treatments include diet, oral medication and insulin shots.
During exercise, the body depletes its stores of sugar, then cuts insulin production to compensate for the lower sugar levels.
But in people taking insulin shots or using a pump, that doesn't happen.
Instead, hypoglycemia sets in, causing symptoms including dizziness, sweating, confusion and nervousness.
Taking too little insulin can cause problems for an athlete too, said Dr. James Desemone, director of the Goodman Diabetes Service at Albany Medical Center.
The key, he says, is setting up a regimen using insulin injections or a pump to mimic the functioning of a normal pancreas during exercise, adjusting how much insulin is given to the body and when.
Paula Harper, 61, started the Diabetes Exercise and Sports Association in 1985, a nonprofit group with about 3,000 members in North America and Europe.
A longtime runner and nurse who has competed in 35 marathons, Harper was frustrated trying to come up with the right formula to keep her blood sugar level up over long distances.
"And trial-and-error can get you in trouble sometimes."
She recalled races when she ate a Fig Newton every two miles to keep her blood sugar up, and with the help of her husband, pricked her finger every five miles to test it.