Ever since recombinant human growth hormones (GH) were produced in the 1980s, many studies on their metabolic effects have been performed. GH has been shown to have a diabetogenic action resulting in glucose intolerance. Even though there is no evidence that GH increases the risk of diabetes, HbA1c, glucose, insulin tests should be carried out during GH treatment. GH increases free fatty acids and glycerol, and inhibits fat formation. Moreover, GH degrades abdominal fat and redistributes it to peripheral areas. GH increases amino acid intake via IGF1, increases protein synthesis by directly enhancing the translation of the transcription mRNA, and inhibits protein degradation to form a positive nitrogen balance. GH produces sodium and water retention effects through the activation of Na+ K+ ATPase in distal nephron and renin-angiotensin-aldosterone axes and ANP receptor down-regulation. Metabolic side-effects with clinical significance due to GH treatment do not occur, however such side-effects of long-acting or high-dose GH treatment should be investigated. GH treatment can be used safely in children, yet it requires continuous and vigilant monitoring.