HYPERINSULINEMIA AS A DETERMINANT OF MICROALBUMINURIA IN ESSENTIAL-HYPERTENSION

Objective To analyze the relationship between insulinemia and urinary albumin excretion in a group of nonobese, young adult hypertensive pat ients, who had never been treated with antihypertensive drugs. Patient s and methods Forty-nine patients who fulfilled the inclusion criteria were included. Twenty-four-hour ambulatory blood pressure monitorings , urinary albumin excretion (UAE) measurements, and an oral glucose-to lerance test measuring glucose and insulin, were performed, and left v entricular mass was measured by echocardiography. Hypertensive patient s were classified as normoalbuminuric when their UAE was < 30 mg/24 h (40 patients; mean UAE 13.4 +/- 7.0 mg/24 h), and as microalbuminuric when their UAE was 30-300 mg/24 h (nine patients; mean UAE 90.5 +/- 86 .6 mg/24 h). Results In comparison with that of the normoalbuminuric g roup, the fasting plasma glucose concentration for the microalbuminuri c group was only slightly higher (100 +/- 9 versus 95 +/- 8 mg/dl, NS) . In contrast, the fasting insulin concentration in the microalbuminur ic group was significantly higher than that observed in the normoalbum inuric group (25.2 +/- 6.7 versus 16.6 +/- 5.2 mu U/ml, P < 0.0001). D uring the oral glucose-tolerance test, the area under the curve (AUG) for glucose (317 +/- 41 versus 253 +/- 53 mg/dl x 2/h, P < 0.001) and the AUC for insulin (253 +/- 171 versus 124 +/- 43 mu U/ml x 2/h, P < 0.001) were significantly higher in the microalbuminuric group than we re those AUC observed in the normoalbuminuric group, After adjustments for age, sex, body mass index and average 24 h ambulatory mean blood pressure were made, the fasting insulin level was associated independe ntly with an increase in UAE in a multiple regression model with base 10 logarithm of the UAE as the dependent variable, Variations in fasti ng insulin level alone accounted for 33% of the UAE variance. In contr ast, the 24 h ambulatory mean blood pressure, rather than the insulin level, was the strongest predictor of the left ventricular mass index. Conclusions Mild hypertensive patients with microalbuminuria were hyp erinsulinemic in the absence of obesity, and their insulin level was t he main determinant of microalbuminuria in these patients, Microalbumi nuria in essential hypertension seems to identify patients with a clus ter of cardiovascular risk factors and a bad risk profile. Thus, asses sment of microalbuminuria may be useful in the stratification of risk in essential hypertension.