Obesity is associated with a higher risk of developing diabetes mellitus (DM), hypertension (HT), and left ventricular hypertrophy (LVH). The present study assessed in the general population the impact of body weight and visceral obesity on the development of alterations in glucose metabolism and cardiac structure, as well as of elevation in blood pressure. In 1412 subjects randomly selected and representative of the general population of Monza, we assessed twice (in 1990/1991 and 2000/2001) body mass index (BMI); waist circumference; office, home, and 24-hour ambulatory (24-hour) blood pressure, fasting glycemia, and left ventricular mass (echocardiography). New-onset high-risk conditions were DM; impaired fasting glucose; office, home, and 24-hour HT; and LVH. The incidence of new-onset DM; impaired fasting glucose; office, home, and 24-hour HT; and LVH increased progressively from the quintile with the lowest to the quintile with the highest BMI values. Adjusting for confounders, the risk of developing new-onset DM; impaired fasting glucose; office, home, and 24-hour HT; and LVH increased significantly for an increase of 1 kg/m2 of BMI and 1 cm of waist circumference (respectively, 8.4% [P<0.01], 9.5% [P<0.0001], 4.2% [P<0.0001], 3.9% [P<0.001], 2.5% [P<0.05], and 5.1% [P<0.001] for BMI and 3.2% [P<0.001], 3.5% [P<0.0001], 1.8% [P<0.0001], 1.5% [P<0.0001], 1.4% [P<0.001], and 2.6% [P<0.0001]). These data provide evidence that an increase in BMI and waist circumference is associated with a linearly increased adjusted risk of developing conditions with high cardiovascular risk, such as DM, impaired fasting glucose, in- and out-of-office HT, and LVH.