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Genetic Risk Factors

Genetic background is a determining factor in the prevalence of type 2 diabetes. Few data exist on specific genetic causes in the APIA population, but some researchers have suggested that the "thrifty gene" theory may be involved in the increased prevalence of diabetes in some minority populations, particularly those with high rates of obesity. The thrifty gene theory, first proposed in 1962, suggests that population groups that experienced alternating periods of feast and famine gradually adapted by developing a way to store fat more efficiently during periods of plenty to better survive famines.

Lifestyle and Medical Risk Factors

Obesity
Obesity is a major risk factor for type 2 diabetes among all races and ethnic groups. The degree to which obesity is a risk factor for diabetes depends not just on overall weight, but also on the location of the excess weight. Central or upper-body obesity is a stronger risk factor for type 2 diabetes than excess weight carried below the waist.³ In a study comparing Japanese people in Japan with Japanese people who had emigrated to Hawaii, the Hawaiian Japanese had a higher rate of obesity and double the prevalence of type 2 diabetes.⁸ The sharp increase in type 2 diabetes in youth has paralleled the dramatic increase of obesity in youth.¹¹

Diet and Physical Inactivity
As a result of migration and modernization, the food choices of some members of APIA subgroups have changed. Many of the APIA populations have abandoned a traditional plant- and fish-based diet and are choosing foods with more animal protein, animal fats, and processed carbohydrates. One study compared the dietary content of similarly aged Japanese-American men living in Seattle, Washington, with that of Japanese men in Japan. The Japanese-American diet was higher in calories, protein, fat, and carbohydrates. The mean daily intake of fat in Japanese-American men was 32.4 grams, in contrast to a mean intake of only 16.7 grams of fat in Japanese men.³ Other studies have shown that, for many Asian Americans, their diet in America is higher in calories and fat and lower in fiber than in their countries of origin.⁸

Most studies have shown lower rates of physical activity in minorities than in non-Hispanic whites in the United States.⁸ With the increase in migration and urbanization, physical activity has been greatly reduced in the APIA population. Urbanization has caused this population to change from a lifestyle characterized by hard labor to a more sedentary one.³

Findings in a study of 8,000 Japanese-American men living in Hawaii suggested that a Japanese lifestyle was associated with a reduced prevalence of type 2 diabetes. Components of this lifestyle included higher levels of physical activity and consumption of more carbohydrates and less fat and animal protein.¹²

Pre-diabetes (Impaired Glucose Tolerance and Impaired Fasting Glucose)
Recent recommendations describe two categories of the physiological state between normal blood glucose and the diabetic range of blood glucose. Individuals are described as having impaired glucose tolerance (a 2-hour glucose value of between 140 and 199 mg/dL during the oral glucose tolerance test) or impaired fasting glucose (a fasting plasma glucose value of between 110 and 125 mg/dL).⁵

Asian Americans have shown higher rates of impaired glucose tolerance than have non-Hispanic whites in a number of studies.⁸ The prevalence of impaired glucose tolerance among Native Hawaiians in one study was 15.6 percent; prevalence rates were constant across age groups.⁹

Hyperinsulinemia and Insulin Resistance
Hyperinsulinemia (higher than normal levels of fasting insulin) and insulin resistance (the inability of the body to use its own insulin to properly control blood glucose) are both associated with an increased risk of developing type 2 diabetes. Hyperinsulinemia often predates diabetes by several years. These factors, possibly linked to the APIA population through genetics and obesity, increase the risk of developing type 2 diabetes.³

source:

http://diabetes.niddk.nih.gov/dm/pubs/asianamerican/index.htm