Targeting glycemic control after pediatric cardiac surgery: The influence of age on insulin requirement

Objective: Factors influencing the development of hyperglycemia and pattern of insulin requirement in children undergoing cardiac surgery are poorly understood. This study investigated the impact of age on the pattern of hyperglycemia and insulin requirement in children after cardiac surgery

 Design: Cohort study, based on a prospectively collected dataset for patients enrolled into the Control of Hyperglycemia in Pediatric Intensive Care trial. 

Setting: A 24-bedded multidisciplinary PICU.

 Patients: Children randomized to the tight glycemic control arm (target blood glucose, 4-7 mmol/L [72-126 mg/dL]) of the Control of Hyperglycemia in Pediatric Intensive Care trial following cardiac surgery. Children were categorized into four age groups (neonate, 1-30 d; infant, 31-365 d; young child, 1-5 yr; older child, 5-16 yr) for analyses of patterns of hyperglycemia and insulin requirement over the 12-hour period following initiation of insulin.

 Interventions: Insulin titration was performed based on blood glucose value and rate of change of blood glucose using an algorithm developed for the Control of Hyperglycemia in Pediatric Intensive Care trial.

 Measurements and Main Results: Of 92 children, 72 children (78%) randomized to the tight glycemic control group developed hyperglycemia (blood glucose, > 7 mmol/L [126 mg/dL]) and received insulin. Older age was associated with higher blood glucose and a higher insulin dose per kilogram over the first 3 hours of the study period (p≤0.02). Cumulative insulin dose was significantly higher in older children (median, 1.3 U/kg [range, 0.2-5.75]) compared with other age groups (neonate, 0.37 [0.05-2.2]; infant, 0.45 [0.05-2.2]; young child, 0.35 [0.05-0.81]) (p = 0.004). Age group, rather than body mass index, carbohydrate intake, or cardiac surgery variables, was the only variable (coefficient: 1.14 0.3; p < 0.001) associated with cumulative insulin dose on multivariate analysis.

 Conclusions: When tight glycemic control is targeted in children who have undergone cardiac surgery, children in the older child age group (5-16 yr) require insulin at significantly higher doses. Further study is needed to understand the mechanisms involved.