Risk Factors for Type 2 Diabetes: Lessons Learned from Japanese Americans in Seattle

Migrant Japanese populations in both the United States and Brazil have for a long time shown a higher prevalence of type 2 diabetes than in native Japanese, suggesting an interaction of lifestyle and genetic predisposition in the etiology of type 2 diabetes. The overall objective of the Seattle Japanese American Community Diabetes Study was to learn more about the etiology and pathogenesis of type 2 diabetes in Japanese Americans. This metabolically based epidemiologic study included extensive assessments of insulin sensitivity, insulin response, and adiposity with the latter including measurements of body fat distribution by both anthropometry and computed tomography. Because of this, the importance of visceral adiposity as a risk factor for abnormal glucose tolerance, hypertension, coronary heart disease, and the metabolic syndrome was demonstrated. In conjunction with an examination of diet and physical activity patterns, the result was a clearer understanding of the etiology and pathogenesis of type 2 diabetes in Japanese Americans. Wepropose that a lifestyle that fosters increased weight gain, especially in the visceral adipose depot, promotes the development of insulin resistance which in turn exposes an underlying reduced beta-cell reserve in susceptible individuals, resulting in glucose intolerance and eventually in many the development of diabetes. We have shown that it may be possible to delay or prevent the development of diabetes through dietary and exercise interventions in individuals identified as having impaired glucose tolerance. The lessons learned from studying migrant Japanese in Seattle may in many ways be applicable to other populations of Asian origin.