The case of Lai's family is symptomatic of a widespread and growing problem of diabetes afflicting younger people in Hong Kong - more often than not those who are obese, statistics show. But on top of the public health concern, there is an economic and emotional cost to this alarming trend. Lai says the disease has placed a strain on her family's relationships.

"She was always fat, even before being diagnosed, so I already had to keep an eye on her diet," Lai says. "But sometimes her father and his side of the family don't agree with me. Her father would play the good guy; that means I'm the bad one. They always think I control her life too much, because I supervise her studies as well as her diet."

DON'T MISS: Top tips to boost your metabolism

But the problem isn't just about the money, says Sarah McGhee, honorary professor at University of Hong Kong's School of Public Health and the primary author of the study.

"I tend to think of the price tag as not being just dollars, but the implications for society," McGhee says. "And I think one of the biggest costs for diabetes is the impact on quality of life of the person with diabetes and their family."

She notes that complications can include stroke, heart disease and early death. One important contributing factor is the Western diet of fast food and soft drinks that children in Hong Kong have been adopting. That's been a long-running argument in Lai's family.

Lai says because she's the only family member who understands that her daughter's disease needs to kept in check with a proper regimen of diet and exercise, other family members indulge her with all kinds of sugary treats she should be avoiding. It even leads to name-calling.

"Sometimes her uncle would say to her, 'Don't listen to that fat monster. I'll take you out to McDonald's.'"

She says her daughter regularly returns from family visits with bags of chocolate, candy and cookies. She once returned with a six-pack of soda, and argued when Lai told her she couldn't have them all.

"Back in our day, we didn't have enough to eat, especially the older people, so all they do is indulge the children without realising the problems it can cause," Lai says. "They don't understand that children can get this disease."

It's not just the Lai family; understanding the dangers of diabetes is something that many patients struggle with, says Dr Ronald Ma Ching-wan, an endocrinologist at Chinese University's department of medicine. 

"Patients think, 'I don't feel a thing, so why should I see a doctor? It's not like I have a lump or I have pain,'" Ma says. "Patients with mildly elevated glucose levels don't show symptoms, so patients think, 'Why should I waste time changing my lifestyle?'"

Even when it should be obvious that a change in lifestyle is important, it isn't always easy, says Eva Li, a nurse at Diabetes Hong Kong, a charity established to help diabetics and raise awareness about the disease. Li has been following the case of Lai's daughter for a while.

"The Health Department has school programmes to promote healthy eating," Li says, pointing to guidelines on what should be dished up for school dinners. "I have seen students just dump all the food - which is low in sugar, salt and oil, and heavy on vegetables - because it doesn't suit their tastes."

Obese children find it difficult to change their eating habits, and this can also have psychological effects. "Sometimes they feel self-conscious and ashamed of their disease. When they go outside, people might call them fat and that takes a toll on their self-esteem," says Li. "That has made Lai's daughter more introverted, so it can affect a patient's psychological well-being and social relationships."

Lai is relieved that her daughter has recently started swimming and exercising more, although her doctors have given up on asking her to take a weight-loss target seriously.

Ma and McGhee both say schools and the government need to think of more and better ways to encourage a healthy diet and regular exercise among local schoolchildren. Parents also need to pay attention to their children's diets. But McGhee also points out there are not many success stories to be gleaned from Western societies, which have been struggling with this problem for much longer.

"I think the West is really losing the battle, and part of the reason is the vested interests of food companies. It's quite difficult to tackle them," McGhee says.

"One of the problems the UK has is that parents of affected children themselves do not have very good diets, and they don't necessarily know how to prepare food that's healthy for their children.

"Hong Kong could avoid that; Hong Kong has traditionally had a fairly good diet - lots of vegetables and not too much fast food - but I just worry that if they lose that tradition, then they'll end up in the same cycle that the UK finds itself in."

McGhee and Ma also point out that, in Asia, the problem goes beyond Hong Kong; Ma has co-authored research on similar trends in India, Sri Lanka and Southeast Asia, and he recently wrote a review of a similarly alarming situation on the mainland for another journal. Ma says that the World Health Organisation has established a commission to end childhood obesity, which he takes as an indicator of the scale of the problem.

On the bright side, Ma says some of his patients have successfully managed their diabetes and obesity.

"A lot of the things we teach patients with diabetes is how to manage it, such as doing more exercise, watching what you eat, eating more healthy food, getting enough sleep," he says.

"When they find out they have diabetes, it is a shock, but patients who are motivated to make changes will improve their lifestyle. They change what they eat, they pay attention to their blood glucose, they lose weight. It's a full-time job but if you do it well, [the disease] is a blessing in disguise."