To investigate the relationships between high-normal blood pressure (BP) and insulin resistance, we examined insulin sensitivity in 306 nonobese and nondiabetic Japanese subjects with various BP categories (optimal BP, normal BP, high-normal BP, and hypertension). Insulin sensitivity was measured from fasting plasma glucose and insulin values and those during a 75-g oral glucose tolerance test by five formulas: the homeostasis model assessment of insulin resistance (HOMA-R), the quantitative

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... ulin sensitivity check index (QUICKI), the oral glucose insulin sensitivity (OGIS) index, and two insulin sensitivity indexes (ISI-composite and ISIstumvoll). The HOMA-R was significantly higher, and the QUICKI was significantly lower in subjects with hypertension than in subjects with optimal BP. Both HOMA-R and QUICKI values showed that high-normal BP patients had a higher (but not significant) degree of insulin resistance than optimal BP patients. The OGIS index was significantly lower in subjects with high-normal BP or hypertension than in subjects with optimal BP. The ISI-composite was significantly lower in subjects with high-normal BP or hypertension than in subjects with optimal BP, and it was also significantly lower in subjects with hypertension than in subjects with normal BP. The ISIstumvoll was significantly lower in subjects with high-normal BP or hypertension than in subjects with optimal BP. The OGIS index, ISI-composite, and ISI-stumvoll significantly decreased with increasing severity of BP status among the normotensive groups (optimal BP, normal BP, and high-normal BP). These findings indicate that insulin resistance is present even in the high-normal BP categories of nonobese and nondiabetic Japanese individuals. (J Clin Endocrinol Metab 88: 3444 -3446, 2003)