Association of beta(3)-adrenergic receptor gene polymorphism with insulin resistance in Japanese-American men

The Trp64Arg variant of the beta(3)-adrenergic receptor (beta(3)-AR) gene i s relatively common in Japanese people. We hypothesized that this variant m ay be associated with obesity and insulin resistance when combined with a w esternized lifestyle. To test this hypothesis, we investigated the relation ships between the beta(3)-AR gene variant and obesity and insulin resistanc e in Japanese-American men, who are known to have a higher prevalence of ty pe 2 diabetes mellitus (DM). The subjects were 152 Japanese-American men li ving in Hawaii, 83 with normal glucose tolerance (NGT). 40 with impaired gl ucose tolerance (IGT), and 29 with DM. The frequency of the Trp64Arg allele of the beta(3)-AR gene was 0.18. almost identical to that of the mainland Japanese. The prevalence of the Trp64Arg allele was 30.1% in NGT, 35.0% in IGT, and 41.4% in DM subjects (nonsignificant). The Trp64Arg variant of the PB-AR gene showed no significant relationship with obesity or insulin resi stance in NGT subjects. However, fasting and 2-hour insulin levels and insu lin resistance as determined by homeostasis model assessment (HOMA) were si gnificantly higher in IGT subjects with the Trp64Arg variant. Although indi ces of obesity were the same in IGT subjects with and without the Trp64Arg variant, differences in the body mass index (BMI) and percent body fat betw een NGT and IGT subjects were greater for individuals with the Trp64Arg var iant. Thus, there is an association between the Trp64Arg variant of the bet a(3)-AR gene and insulin resistance in Japanese-Americans with IGT. Copyrig ht (C) 1999 by W.B. Saunders Company.