We investigated the possibility of variations in the genetic transmission of insulin sensitivity in the offspring of spontaneously hypertensive rats (SHRs) and Wistar Kyoto rats (WKYs) obtained from different sources (Charles River, Tokyo, Japan [NCrj]; and Funabashi Farm, Chiba, Japan [Izm]) with the insulin suppression test (IST) using a somatostatin analog, glucose, and insulin. The steady-state blood glucose (SSBG) in the IST and the glucose infusion required (GIR) in the euglycemic-hyperinsulinemic clamp differ significantly between obese and lean Zucker rats, indicating that both methods are useful for identifying insulin resistance. The fasting blood glucose and SSBG of the IST were significantly higher in SHR Izm than in WKY Izm . We did not observe a significant difference between SHR NCrj and WKY NCrj . These results indicate that the genetic transmission of hypertension and impaired insulin sensitivity may be variable and that insulin resistance does not play an important role in the pathogenesis of hypertension in the SHR.