IGF1 and Laron syndrome: In healthy adults and adolescents during puberty, increased GH levels impair glucose tolerance and induce insulin resistance.82,83 Conversely, adults with Laron syndrome have reduced circulating IGF1 and increased insulin sensitivity.45,46,84 This is supported by studies in mice85 and dogs.86 Blocking the effects of GH in patients with acromegaly improves diabetes and glucose metabolism.