Like many teenage girls, Lee Ann Thill was obsessed with her appearance. A diabetic, she was already suffering from bulimia - forcing herself to throw up to lose weight. But it wasn't enough, and she'd recently put on 20 pounds.

Diabetes sufferer Lee Ann Thill, 34, looks at her insulin pump after using her glucose meter to check her blood sugar at her home in Magnolia, N.J., Monday June 11, 2007. [AP]

Then one day at a camp for diabetic teens, she heard counselors chew out two girls for practicing "diabulimia" - not taking their insulin so they could lose weight, one of the consequences of uncontrolled diabetes.

Don't you realize you could die if you skip your insulin? the counselor scolded. Don't you know you could fall into a coma or damage your kidneys or your eyes?

But that's not what registered with Thill, who has Type 1, or juvenile diabetes. Instead, she focused on this: Skipping insulin equals weight loss. For the next 17 years, diabulimia was her compulsion.

"I took just enough insulin to function," said Thill, now 34, of Magnolia, N.J.

Today, she worries about the long-term damage that may have come from her weight obsession. At 25, a blood vessel hemorrhage in her eye required surgery. At 28, doctors told her she had damaged kidneys.

"I'm fearful for the future," Thill said. "I feel very strongly that had I taken care of myself, I could have lived as long as anyone without diabetes. I don't think that's going to happen now."

Diabulimia is usually practiced by teenage girls and young women, and it may be growing more common as the secret is exchanged on Internet bulletin boards for diabetics and those with eating disorders. One expert who has studied the phenomenon estimates that 450,000 Type 1 diabetic women in the United States - one-third of the total - have skipped or shortchanged their insulin to lose weight and are risking a coma and an early death.

"People who do this behavior wind up with severe diabetic complications much earlier," said Ann Goebel-Fabbri, a clinical psychologist at the Joslin Diabetes Center in Boston.

The American Diabetes Association has long known about insulin omission as a tactic to lose weight. But "diabulimia" is a term that has only cropped up in recent years and is not a recognized medical condition, said Barbara Anderson, a pediatrics professor at Baylor College of Medicine in Houston.

Type 1 diabetes is a disorder in which the body's own immune system attacks insulin-producing cells in the pancreas. People with this disease produce little or no insulin, so they take shots of the hormone daily.

It differs from Type 2, the form associated with obesity and which accounts for about 90 to 95 percent of all diabetes.

Insulin is vital for delivering glucose from the bloodstream to the body's cells. Without insulin, cells starve even while the bloodstream becomes burdened with too much glucose.

When Type 1 diabetics skip or reduce their insulin, they risk falling into a coma or even dying. Blindness, amputations and kidney failure are some of the long-term complications that can develop.

Warning signs for diabulimia include a change in eating habits - typically someone who eats more but still loses weight - low energy and high blood-sugar levels, Goebel-Fabbri said. Frequent urination is another signal. When sugars are high, the kidneys work overtime to filter the excess glucose from the blood.

This purging of sugar from the body through the kidneys is similar to someone with bulimia, who binges and then purges, or vomits, Anderson said.

Studies show that women with Type 1 diabetes are twice as likely to develop an eating disorder. Ironically, good diabetes management, which requires a preoccupation with food, counting carbohydrates and following a diet, may lead some to form an unhealthy association with food, Goebel-Fabbri said.

Jacq Allan, 26, of London, is a diabulimic. When recently interviewed, she said she had not taken her insulin shots for two weeks and rarely takes them regularly. She weighs 42 pounds less than she did a year ago.

Allan is stuck between two fears: taking insulin, which may lead to weight gain, and the damage her destructive compulsion is doing to her body.

"I'm terrified of insulin," Allan said. "Every morning I wake up and think maybe I should go to the hospital."

Diagnosed with Type 1 diabetes nearly three years ago, Allan said she can feel the constant, sky-high sugar in her blood. Her list of ailments - chest pain, heart palpitations, muscle cramps, bacterial infections and lower back pain - are not the usual health problems of a twenty-something.

"I'm constantly worried that my eyes are going to go, but they seem relatively OK for the moment," she said. "I always wonder if this will be the day that some major organ fails. I kind of want something to happen because then maybe I'll stop."

Gwen Malnassy, 21, of Santa Monica, Calif., detailed her struggle with diabulimia for three years in a diary she posted on the Internet.

"If you don't think it will happen to you, don't fool yourself," writes Malnassy, diagnosed with diabetes at 9, in her final entry 11 months ago. "I believed the same."

Doctors diagnosed Malnassy with both anorexia and bulimia at 13, she said.

"I would look at magazines and think that if I looked like the models, I would have more friends and be more popular," Malnassy said in a recent interview.

She began withholding insulin at 17 after learning of the practice during a doctor's visit and continued withholding insulin off and on until last year.

Malnassy continues in her online diary: "I will say it again. Reach out; get help. Do not fall; do not let the disorder consume you. It's a miserable way to exist."