Differentiation between constitutional (genetic-based) and metabolic (environmental-based) macrosomia during fetal life is a novel idea. A better understanding of sonographic findings and their combination with maternal risk factors offers the possibility of identifying metabolic macrosomia. The HAPO study has provided sufficient data to allow us to better understand the associations between adverse pregnancy outcome and 'non-diabetic' hyperglycemia, hopefully leading us towards a universal consensus (agreed by all leading international authorities - WHO, CDC, FIGO, ACOG, ADA, EASD and EAPM) to accept new (probably less stringent) diagnostic criteria for GDM, and more efficient management during pregnancy. A management approach which focuses on early, efficient and universally accepted diagnostic criteria of GDM, combined with advances in imaging technologies, may facilitate early and efficient diagnosis of fetal overgrowth. Combining the data from the HAPO and MFMU studies as well as sonographic data with the recent proof supporting intensive maternal treatment for even the mildest forms of carbohydrate intolerance provides further evidence not only that this approach may reduce birth trauma and short-term complications but that it may overcome long-term complications for the offspring.