Serum levels of glucose and insulin in the early post-operative period. Serum levels of glucose and insulin are studied during 12 hours in the early post-operative period after intra-abdominal surgery. Five groups of non diabetic patients are perfused with incremental doses of glucose, G. I : no glucose, G. II : 8,33 g · h −1 of glucose during 6 hours, G. III : 16,66 g · h −1 of glucose during 6 hours, G. IV : 16,66 g · h −1 of glucose with 20 u insulin; G. V : 16,66 g · h −1 of glucose with 40 u insulin. In all groups a significant rise in serum levels of glucose is observed (10,5–15,6 mmol · 1 −1). At the same time serum level of insulin remains unchanged except when insulin is infused. However exogenous insulin is unable to prevent the serum level of glucose to rise post-operatively.