Long-term GH treatment decreases total body fat including visceral fat. Decreases in central fat as assessed by waist to hip ratio have been reported in some studies, but not in others. Administration of GH causes insulin resistance acutely but long-term therapy may restore glucose sensitivity. GH treatment increases lipoprotein (a) (Lp (a)) levels but its effects on other lipoproteins are still controversial. Some studies have reported decreases in LDL cholesterol with or without increases in HDL cholesterol with GH administration, while others have not. Twelve months of GH replacement improves left ventricular mass and cardiac performance in young adults with GHD. Key factors likely involved in the discrepant findings include heterogeneity of patients studied in terms of age of onset of the GH deficiency (childhood versus adulthood), gender, severity of GHD and methodologic issues such as dose and duration of GH administration. In addition, many of the studies have no control period.