The human beta(3)-adrenergic receptor (beta(3)AR) is expressed specifically in adipose tissues, and its activation is activated in brown adipose tissues during thermogenesis and in white adipose tissues during lipolysis. We investigated the relationship between a polymorphism of the beta(3)AR gene and the clinical features of type 2 diabetes mellitus. Studies were conducted in 30 type 2 diabetic patients (15 males and 15 females). Analysis of polymorphisms of the beta(3)AR gene was performed by a pin-point sequencing method using the hair of the subjects. Preperitoneal (P-fat) and subcutaneous fat (S-fat) levels were determined by ultrasonography. We found a Trp(64)Arg allele of the beta(3)AR gene in the hair of 27% of all patients. The patients with this mutation showed a significantly younger onset-age of diabetes than those of the wild type. The body mass index, serum GPT levels, fasting immunoreactive insulin (IRI) and daily urinary C-peptide reaction (CPR) in the mutation group were markedly higher than in the wild type group. The P-fat, serum cholesterol and leptin concentrations tended to be higher in the mutation group. Patients in the mutation group had a significantly higher prevalence of hypertension (80%) compared with those in the wild type group (20%).
Conclusions: The present results suggest that the clinical features of diabetic patients with a missense mutation in the beta(3)AR gene are substantially distinct from those of the wild type patients. These specific features include obesity, hyperinsulinemia, hypertension, and an increase in preperitoneal fat.