The 14-year-old Brisbanite suffers a double whammy of diabetes and coeliac disease (gluten intolerance).
Hilary has to carefully monitor food intake and blood glucose levels for her insulin dependent Type 1 diabetes condition.
"It just means I'm not able to do a lot of impulsive fun things," she says.
"I can have the ice-cream but I have to think about it a lot more... and remember to give myself insulin with it."
Sleepovers can become tricky, she says.
Type 1 diabetes is caused by an auto-immune destruction of insulin-making cells in the pancreas.
"I have to take blood glucose levels through out the day, which is a tiny finger prick," Hilary says.
She also has to watch her glucose levels after exercise because they can go quite low.
If blood sugar levels are not managed and remain very high for extended periods, patients can experience Diabetic Keto Acidosis (DKA).
DKA symptoms include weight loss, increased thirst, nausea, vomiting and fatigue.
Sometimes patients suffering DKA will have to visit hospital emergency rooms for treatment.
Diabetes management is important because high blood glucose levels can cause kidney and vascular damage.
"People with Type 1 Diabetes look healthy and it can be confusing to understand how serious the condition really is," Hilary says.
Type 1 diabetes has no cure but is controlled through insulin doses which need carbohydrates to metabolise.
For years Hilary gave herself about six insulin injections each day but now a high-tech pump device connected to her abdomen feeds her insulin continually.
The pump delivers insulin in two ways - bolus and basal doses.
Bolus doses are needed about half an hour before a meal to cover the blood glucose level rise from eating.
Basal is a low continuous dose of insulin that is the minimum to keep the body alive and the liver going.
Sometimes Hilary needs jelly lollies to correct low blood glucose levels which means she's had too much insulin.
"That doesn't happen in (non-diabetics) because their pancreas just switches off," Hilary says.
She says the pump technology has taken a lot of the guess work out of insulin doses and increased her level of independence.
"You enter in the exact amount of grams of carbohydrates that you eat and then you add your blood glucose level and then it calculates that with your insulin to carb ratio," she says.
"That turns it into a dose that's ideal. It does the thinking for you."
Her mother Megan says the pump is a godsend.
"She used to need to ring me twice a day at school," she said.
"She'd ring at morning tea and lunch time so she could check how much (insulin) to take. Then she'd have to prepare the injections.
"It was nuisance!"
Hilary also carries a back up treatment in case of emergencies.
"She can get sick very quickly if something goes wrong... if she goes anywhere she takes the (injection) pens as a back up," Megan says.
Hilary says there was no family history of diabetes in her case but for others there can be.
She says she doesn't see her condition as a life sentence.
"I never get sad about it," she says.
"Getting sad won't fix anything... you just deal with it."
Megan: "Living is preferential, there is no choice, it doesn't matter if you don't like it."
"We're lucky to have the treatment."
Megan says occasionally some nagging is required.
"Some significant reminding strategies are in place," she says.
"But I find it hard, I'm not a natural nagger."
The combination of Type 1 and coeliac disease is increasingly common, Hilary says.
Coeliac disease is an autoimmune disorder causing sufferers to have an intolerance to gluten protein found in wheat, rye and barley.
Sufferers can experience chronic diarrhoea and fatigue.
Unfortunately, medical experts recommend diabetics eat mostly low glycaemic index (GI) carbs and most of these contain gluten.
(Glycaemic index describes the rate at which carbohydrates are metabolised.)
Coeliac carbohydrates often have a higher GI which adds another layer of complexity to the calculation of Hilary's insulin dose.
Megan says her daughter's condition has huge implications for family meal preparations and often results in two dinner menus.
"There's always got to be special pasta, corn chips, anything with rice is fine, Hilary can't eat normal bread.
"She invariably has something separate.
"The other (family members) like ordinary pasta."
The complex diet was a learning curve and requires creativity in the kitchen, Megan says.
"It takes constant thinking about," she says.
"Hilary does a beautiful job of baking gluten free cakes."
