Circulating Insulin and Insulin Growth Factor-1 Are Independent Determinants of Left Ventricular Mass and Geometry in Essential Hypertension

Background—It is unclear whether insulin and insulin-like growth factor-1 (IGF-1) are independent determinants of left ventricular (LV) mass in essential hypertension. Methods and Results—We studied 101 never-treated nondiabetic subjects with essential hypertension. All had 24-hour noninvasive ambulatory blood pressure (ABP) monitoring and a 75-g oral glucose tolerance test. We determined fasting glucose, insulin, and IGF-1 and postload glucose and insulin 2 hours after glucose. Insulin resistance was estimated by the homeostasis model assessment (HOMAIR) formula. LV mass showed an association with body mass index (BMI) (r50.47; P,0.01), postload insulin (r50.54; P,0.01), HOMAIR (r50.39; P,0.01), and IGF-1 (r50.43; P,0.01) and a weaker association with average 24-hour systolic and diastolic ABPs (r50.29 and r50.26; P,0.05) and basal insulin (r50.31; P,0.05). Relative wall thickness was positively related to IGF-1 (r50.39; P,0.01) but not to fasting or 2-hour postload insulin, HOMAIR, and glucose. In a multiple regression analysis, the final LV mass model (R 50.64) included IGF-1, postload insulin, average 24-hour systolic ABP, sex, and BMI. IGF-1 and postload insulin accounted for .40% of variability of LV mass. The final model (R50.36) for relative wall thickness included IGF-1 (16% total explained variability), average 24-hour systolic ABP, sex, BMI, and age but not insulin and HOMAIR. Conclusions—These data indicate that insulin and IGF-1 are powerful independent determinants of LV mass and geometry in untreated subjects with essential hypertension and normal glucose tolerance. (Circulation. 1999;100:1802-1807.)