As many as 65 percent of around 4.5 million diabetes patients in Vietnam are unaware they have the chronic disease, the Vietnam Nutrition Association (Vinutas) said at a recent workshop.
Vinutas said that those who do not detect the disease early for proper treatment can suffer dangerous complications, including kidney failure, high blood pressure, coronary diseases, blindness, impotence and infection.
Doctors warn that diabetes could be a "silent killer" and it is growing in developing countries.
Dr Tu Ngu, Vinutas general secretary, said diabetes can be controlled if the patients undergo periodical examination and treatment to reduce blood sugar concentration and detect possible complications.
"In order to reduce blood sugar concentration, patients must follow proper dietary regime," he told the workshop on November 6.
Ngu advised diabetes patients to eat more fiber-rich food, fruits, and vegetables and eat less fat-rich food and red meat.
Tran Thi Bich Thuy, a doctor at Trieu An Hospital in Ho Chi Minh City, said diabetes is the main contributor to kidney failure and blindness for people of working age.
Thuy said diabetes patients should not eat beyond their daily calorie needs, but at the same time they must make sure not to skip meals.
"The best food for diabetes patients is food with a low glycemic index, or GI, like unpolished rice, rice vermicelli, noodles, sweet potato, beans, skim milk, and non-sweet fruits.
"They should not eat biscuits, jam, dried fruits, sugared soft drinks, animal viscera and salty food.
Doctors at the workshop advised diabetes patients to change their lifestyles such as to reduce drinking beer or wine, give up smoking, and take up some sports like jogging, bicycling, swimming, or badminton.
Diabetes is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced.
There are three main types of diabetes: type 1 diabetes, type 2 diabetes and gestational diabetes.
Type 2 diabetes is often caused by obesity, lack of exercise and unhealthy eating habits.
Last year, a survey of adults in Ho Chi Minh City, Vietnam's largest city, found 11 percent of men and 12 percent of women have undiagnosed type 2 diabetes.
The research, published on July 7 in the journal Diabetologia, shows more Vietnamese suffer from an obesity-linked form of the disease than the 3.5 percent estimated by the Brussels-based International Diabetes Federation.
The increasing burden of diabetes reflects dietary and lifestyle changes related to Vietnam's economic growth and Westernization, the authors said. The findings indicate better surveillance is needed to ensure diabetic patients get treatment to lower their risk of heart disease, stroke and kidney failure.