2015 Yutaka Seino Distinguished Leadership Award Lecture: The Japanese American Community Diabetes Study and the ‘canary in the coal mine’

The rising tide of diabetes in Asia has been preceded by high prevalence rates of diabetes among migrant Asian populations in the USA and elsewhere. A 1963 report from Hawaii showed that diabetes was much more prevalent in Japanese Americans than in Caucasians. The Japanese American Community Diabetes Study was begun in Seattle, Washington, to examine why this was the case, and explore the etiology and pathogenesis of type 2 diabetes among Japanese Americans who were Nisei (second generation) and Sansei (third generation) descendants of the original immigrants to the USA from Japan. This research was planned to be a metabolically‐based longitudinal epidemiological study that assessed lifestyle factors, insulin sensitivity, insulin secretion and adiposity, including measurements of body fat distribution by anthropometry and computed tomography ( CT ). An important conclusion from this research was that visceral adiposity was a powerful risk factor for metabolic disease. Our observations suggested that among susceptible Japanese Americans lifestyle led to weight gain, especially in visceral fat depots, that in turn led to decreased insulin sensitivity that unmasked a reduced β‐cell reserve, resulting in hyperglycemia and type 2 diabetes. This process can be prevented by dietary and exercise intervention. Thus, the Japanese American population has served as an early warning system for type 2 diabetes in Asians, just as caged canaries were used by coal miners as an early warning system for harmful gases in coal mines.