Ann Goebel-Fabbri, a clinical psychologist and assistant professor in psychiatry at Harvard Medical School, has worked with many type 1 diabetic patients suffering from eating disorders at the Joslin Diabetes Center.
She said that there isn't a clear reason why type 1 diabetics have an increased risk for having an eating disorder, but she suspects that part of the problem is the way diabetics have to focus on food intake, their carb level and calories.
"The treatment itself [means] paying close attention to food and time of eating," said Goebel-Fabbri. "Oftentimes, that can mirror an eating disorder mindset."
In high school, the effects of Williams' diabulimia began to show.
She was constantly dehydrated because her body was trying to flush excess sugar through her urine. At night, she would go to the bathroom up to 20 times a night and was known for constantly carrying a two-liter bottle of soda with her at all times.
With her blood sugar running so high, Williams was also often sleepy and fell asleep in class. During her senior year, she was voted "Most Likely to Fall Asleep at Graduation."
When she went to the doctor with high blood sugar levels, she made up excuses that she had forgotten to take her insulin or that she had injected it improperly.
"All I heard from doctors is 'Why, can't you manage this? ... Is it that hard?" Williams said.
She said they never mentioned that she might be suffering from an eating disorder.
Diabulimia can be terrifyingly easy to hide. Williams could eat as much as she wanted and lose weight. Her other symptoms of fatigue and irritability could be explained as the normal behavior of a teenager.
Amy Criego, the chairwoman for pediatric endocrinology at the International Diabetes Center, said that the symptoms for diabulimia closely mimic poor diabetes control.
"Sometimes it gets hard to distinguish what's going on," said Criego, who added doctors can be wary of bringing up eating disorders with adolescent patients. "People get cautious of asking [about insulin restriction] because they don't want to give them ideas either."
Eventually, in her junior year of high school, Williams' family recognized that she was suffering from an eating disorder and put her in an eating disorder treatment center.
However, Williams said, the counselors at the center weren't used to treating a type 1 diabetic and never monitored her insulin intake.
Even in treatment, whenever she started to gain weight she would simply reduce her insulin intake again.
"People with this combined diagnosis [need a] team with eating disorder people and a diabetes education staff. That's the ideal," said Criego. "The treatment is very different."
Another problem is that common eating disorder treatments can conflict with basic diabetes care. For example diabetic patients have to pay careful attention to what they eat and how their body reacts to food, while eating disorder patients are encouraged to ignore food labels.
"A lot of the eating disorder programs take the focus off of food, you have to ignore your body perception," said Criego. "You can't do that with type 1 diabetes. You have pay attention to numbers."