The perinatal period is known to be a critical period for pancreatic development, and the impact of prematurity on the development of insulin secretion and sensitivity is poorly defined. Premature infants are at risk of hyperglycaemia which is a marker of relative insulin deficiency which impacts on anabolism both directly and indirectly by regulation of insulin like growth factors. The use of insulin in preterm infants and prevention of hyperglycaemia could also effect immune function, lipid metabolism, growth and IGF-I generation leading to improved short term clinical outcomes such as retinopathy of prematurity. It may also have longer term health effects however the outcomes of clinical trials are currently awaited.