Insulin resistance is a characteristic feature of primary hypertension independent of obesity

The relationship between abnormalities in carbohydrate metabolism and hypertension was studied in 143 newly detected hypertensive patients (59% obese) of both sexes (90 males, 53 females) and compared with 51 normotensive controls. Insulin-mediated glucose disposal assessed with the euglycemic insulin clamp technique was significantly decreased in both non-obese (7.2 ± 2.1 mg/kg/min; P < .05) and obese hypertensives (5.1 ± 2.1 mg/kg/min; P < .01) compared with the controls (8.4 ± 1.8 mg/kg/min). The decrease in insulin sensitivity and increase in basal insulin as well as a decreased rate of glucose disposal after an intravenous glucose tolerance test (IVGTT) were verified also after statistical adjustment for sex, age, body mass index, and waist-hip ratio. The insulin index (ratio between peak and basal insulin) during IVGTT was significantly decreased in the hypertensive patients (P < .001). After the statistical adjustment for the factors mentioned the following lipid abnormalities were still significant: total cholesterol (6.25 ± 1.12 mmol/L non-obese; 6.06 ± 1.20 mmol/L obese; 5.41 ± 1.02 mmol/L controls), triglycerides (1.70 ± 0.74 mmol/L nonobese; 2.26 ± 1.13 mmol/L obese; 1.24 ± 0.53 mmol/L controls) and free fatty acids (0.57 ± 0.20 mmol/L nonobese; 0.59 ± 0.20 mmol/L obese; 0.48 ± 0.15 mmol/L controls). This study shows that after correction for a series of probable confounding variables, hypertension emerges as part of a syndrome characterized by major abnormalities of carbohydrate, and lipid metabolism, which independently or in concert may act as important risk factors for cardiovascular disease.