Diabetes mellitus (DM) is characterized by chronic hyperglycemia and impaired carbohydrates, lipids, and proteins metabolism caused by complete or partial insufficiency of insulin secretion and/or insulin action. There are two primary forms of diabetes, insulin-dependent diabetes mellitus (type 1 diabetes mellitus, T1DM) and non-insulin-dependent diabetes mellitus (type 2 diabetes mellitus, T2DM). T2DM is the most common form of DM, which accounts for 90% to 95% of all diabetic patients

 1 and is expected to increase to 439 million by 2030

 2. In China, the latest statistical data show that diabetes and pre-diabetes are prevalent among people older than 20-year-old, with the percentages being 9.7% and 15.5% for T1DM and T2DM, respectively

 3. T2DM mostly results from the interaction among genetic, environmental and other risk factors. Furthermore, loss of first-phase of insulin release, abnormal pulsatility of basal insulin secretion, and increased glucagon secretion also accelerate the development of T2DM 4

5. Although T2DM patients are generally independent of exogenous insulin, they may need it when blood glucose levels are not well controlled with diet alone or with oral hypoglycemic drugs. In addition, people with T2DM are often accompanied by complications, such as cardiovascular diseases, diabetic neuropathy, nephropathy, and retinopathy. Diabetes and its associated complications lower the quality of people’s lives and generate enormous economic and social burdens 6.

 

EPIDEMIOLOGY

T2DM has become an observably global public health problem. Analysis of recent statistical data reveals that T2DM has several new epidemiological characteristics. Firstly, diabetes keeps a steady increase in developed countries, such as United States and Japan. And it is worthy of note that T2DM has become a serious issue at an alarming rate in developing countries. It is predicted that T2DM will continue to increase in the next twenty years, and more than 70% of the patients will appear in developing countries, with the majority of them being 45-64 years old

 7. Even today, seven out of top ten countries with the largest number of diabetes patients are low- or middle-income countries, including India, China, Russia, Brazil, Pakistan, Indonesia, and Bangladesh

 7, among which the prevalence rates are 12.1% and 9.7% in India and China, respectively 8

, 9. Secondly, although advancing age is a risk factor for T2DM, rising rates of childhood obesity have resulted in T2DM becoming more common in children, teenagers and adolescents, which is a serious emerging of the epidemic and a new public health problem of significant proportions 10.