GH promotes protein synthesis and the use of fats for fuel, which conserves stores of glucose and lowers body fat levels. Most of these effects are coordinated indirectly by IGF's (somatomedins) which stimulate blood amino acid uptake and incorporation into cellular proteins throughout the tissues of the body. IGF also stimulates the uptake of sulfur into cartilage matrix (chrnodroitin sulfate).
GH mobilization of fats to the cells for fuel increases blood levels of fatty acids, decreases the rate of glucose uptake and metabolism, and encourages the liver to activate glycogen breakdown and release of glucose into the blood. The rise in blood glucose is the diabetogenic effect because the body spares glucose and the high blood levels of glucose is typical of diabetes mellitus. Normally when blood glucose levels rise, hyperglycemic hormones are not released but when hyperglycemia becomes excessive, the person begins to feel nauseated wheich activates the Sympathetic Nervous System (SNS) in the form of the flight-or-fight response. The consequence is the body activates all the reactions that normally occur in the hypoglycemic (fasting) state to make glucose available (gycogenolysis, lipolysis, and gluconeogenesis). Thus the already high blood glucose levels rise even higher.
This will eventually burn out the beta cells of the pancreatic islets (islets of Langerhans) that produce insulin leading to an even more dramatic insulin and blood glucose imbalance.
The rise of fatty acids can lead to ketoacidosis which can result in hyperventilation of the respiratory system to raise the blood's pH level (lowering blood levels of CO2 content) and if left untreated can disrupt heart activity of oxygen transport and can lead to death and coma.
Studies have proven that while GH increases muscle mass it does not increase muscle strength in athletes or the elderly. Plus it has the possibility to result in acromegaly (enlarged extremities like hands, feet, and face).