McNeely and Boyko (1) recently demonstrated that the BMI-adjusted odds ratio for type 2 diabetes in Asian Americans was 1.6 times that of white Americans. Interestingly, there was no significant difference between the preadjusted values of these two ethnic groups. As the BMI adjustment only affected Asians, it is possible that the influence of BMI on the development of type 2 diabetes is more potent in Asians than in other ethnic groups (1).

It is well known that the average BMI of Asians is lower than that of other ethnic groups, principally because of the significantly lower proportion of obese subjects (BMI ≥30 kg/m2), an observation that was also noted in the recent U.S. study (1). We have reported previously that lower BMI is of particular relevance in patients with type 2 diabetes (2). The BMI of Japanese diabetic patients is similar to that of the Japanese population as a whole (∼23 kg/m2 for both), indicating that Japanese diabetic patients on average are not obese. This contrasts with white diabetic patients who have a much higher BMI (29 kg/m2) than that of the white population as a whole (24 kg/m2). The similarity in BMI between diabetic and nondiabetic subjects is an important characteristic of type 2 diabetes in Asians and has been shown in both Japanese and Thai cohorts (3).

It can be speculated that these results suggest that Asians are more susceptible than other ethnic groups to type 2 diabetes in response to a relatively small increase in BMI, despite having a lower baseline BMI (4). The mechanism underlying this phenomenon is unclear, but we have recently found in Japanese subjects that overeating is not necessarily correlated with obesity (5) and that being overweight (maximum BMI ≥25 kg/m2) is not significantly associated with the risk of type 2 diabetes (6). Therefore, the development of type 2 diabetes linked to obesity caused by overeating, which is regarded as a common feature in the white population, may not be typical in Asians. This suggests that it may be necessary to develop modified diabetes care and prevention strategies for different ethnic groups.

McNeely MJ, Boyko EJ: Type 2 diabetes prevalence in Asian Americans: results of a national health survey.
Diabetes Care
Sone H, Ito H, Ohashi Y, Akanuma Y, Yamada N, Japan Diabetes Complication Study Group: Obesity and type 2 diabetes in Japanese patients (Letter).
Aekplakorn W, Stolk RP, Neal B, Suriyawongpaisal P, Chongsuvivatwong V, Cheepudomwit S, Woodward M: The prevalence and management of diabetes in Thai adults: the international collaborative study of cardiovascular disease in Asia.
Diabetes Care
McNeely MJ, Boyko EJ, Shofer JB, Newell-Morris L, Leonetti DL, Fujimoto WY: Standard definitions of overweight and central adiposity for determining diabetes risk in Japanese Americans.
Am J Clin Nutr
Sone H, Yoshimura Y, Ito H, Ohashi Y, Yamada N, Japan Diabetes Complications Study Group: Energy intake and obesity in Japanese patients with type 2 diabetes.
Wang L, Yamaguchi T, Yoshimine T, Katagiri A, Shirogane K, Ohashi Y: A case-control study of risk factors for develop-ment of type 2 diabetes: emphasis on physical activity.
J Epidemiol