ASSOCIATION OF INSULIN-RESISTANCE AND HYPERINSULINEMIA WITH DISTURBEDLIPID-METABOLISM IN PATIENTS WITH ESSENTIAL-HYPERTENSION

To clarify the association of insulin resistance and hyperinsulinemia with lipid metabolism in patients with essential hypertension (EHT),,v e used the euglycemic hyperinsulinemic glucose clamp technique (GC) an d the 75-g oral glucose tolerance test (OGTT) to compare the character istics of glucose and lipid metabolism in insulin-resistant patients w ith essential hypertension (EHT-R) with those in insulin-nonresistant patients with essential hypertension (EHT-N) and normotensive subjects (NT). Twenty-eight NT and 42 EHT whose body mass index (BMI) was less than 28 kg/m(2) mere studied to eliminate the effects of obesity on i nsulin sensitivity and lipid metabolism. Insulin sensitivity was evalu ated by GC and expressed as metabolic clearance rate of glucose (M val ue, mg/m(2)/min). Mean -ISD of the M value in NT (145.0 mg/m(2)/min) w as chosen as the cutoff point for insulin resistance. On the basis of this value, 33.3% of the EHT were EHT-R. There was no significant diff erence in age or BMI among the three groups. Blood samples were collec ted before GC to measure levels of total cholesterol (TC), triglycerid e (TG), free fatty acid (FFA), and HDL cholesterol (HDL-C). EHT-R had significantly higher levels of fasting blood sugar, fasting immunoreac tive insulin, insulin at 120 min (IRI-120), and summation of insulin o r blood sugar (BS) during the OGTT, as compared with NT and EHT-N. EHT -R also had significantly higher FFA and TG than the other two groups, while there was no difference in FFA or TG between EHT-N and NT. TC a nd HDL-C were similar in the three groups. There was either a signific ant negative correlation, or a trend toward negative correlation, betw een M value and FFA (r = -0.50, p < 0.05) or TG (r = -0.24, p < 0.1). There were significant positive correlations between IRI-120 and FFA ( r = 0.35, p < 0.05) or TG (r = 0.29, p < 0.05). There was a positive c orrelation (r = -0.36, p < 0.01) between Sigma BS and FFA, while no ot her significant relation was found between Sigma BS and serum lipids. In summary, (i) 33.3% of EHT were found to be insulin resistant, when insulin resistance was defined as M value < 145.0 mg/m(2)/min, i.e., m ean -ISD of the M value of NT; (ii) these EHT-R had higher levels of B S, insulin, FFA, and TG than did NT and EHT-N; (iii) EHT-N showed no d ifference in the levels of BS, insulin, or lipid, as compared with NT; and (iv) the levels of FFA and of TG correlated negatively with insul in sensitivity and positively with the insulin level during the OGTT. These results suggest that disturbances of glucose and lipid metabolis m in EHT may be? related to both insulin resistance and compensatory h yperinsulinemia, and that EHT-R mag have more risk factors for arterio sclerotic complications than EHT-N.