Left ventricular (LV) mass that develops as cardiac adaptive remodeling represents a powerful independent predictor of cardiovascular morbidity and mortality in the general population and in several clinical conditions, including essential hypertension. However, many studies have shown that blood pressure explains only 10% to 25% of the variation in LV mass, supporting the hypothesis that other factors, such as genetics or metabolics (insulin-resistance/hyperinsulinemia), are involved in the cardiac growth in human hypertension. Essential hypertension is also characterized by insulin-resistance/hyperinsulinemia, which may directly induce LV hypertrophy through the stimulation of insulin-like growth factor-1 receptors, abundantly expressed in myocardium. Taken together, we investigated the growth effect of fasting insulin, associated with angiotensin-converting enzyme-gene polymorphism, on cardiac mass in a group of previously untreated hypertensive patients.