Untreated or uncontrolled, diabetes can cause many long-term and acute complications, including cardiovascular disease, retinal damage, diabetic foot (a common cause of amputation in China), kidney damage, and diabetic ketoacidosis, an acute condition that is lethal.

A survey by the Chinese Diabetes Association in 2010 with a sample of about 5,000 diabetics found that about 20 percent of them had kidney damage, 25 percent had heart disease, half of them suffered from high blood pressure and one-third of them had diabetes-related retina damage.

About 50 to 70 percent of the patients had mild to severe nerve damage that affects sensation, movement and organ function.

"Diabetes is a chronic condition that needs consistent healthcare to control its progression," Xu says.

"Medication is important, but a healthy lifestyle, including quitting smoking and alcohol, maintaining a healthy body weight and having a light diet, is also very important."

Hu Jianzhong, 56, a Beijing resident who was diagnosed when he was 33, says he is lucky to live in Beijing, where he has access to professional knowledge and useful advice on disease control.