Rationale: Abnormally low and high levels of insulin-like growth factor-I (IGF-I) are both associated with increased metabolic risk. Since (U-shaped) associations of IGF-I, within the normal range, have also been found with cardiovascular risk factors and disease in the general population, it would be interesting to investigate if this association can also be found in growth hormone deficient (GHD) adults treated with Growth Hormone (GH). This could be of interest for endocrinologists prescribing GH in clinical practice because strict dosing may become even more important. Next to that, scientific evidence for clinical practice is wanted.