Clinical outcomes of pediatric metformin exposures reported to the National Poison Data System®

Introduction: Prior studies suggest metformin exposures in young pediatric patients are low risk, and a triage threshold of 85 mg/kg can be used to reduce unnecessary evaluations. Our objective was to analyze single-substance metformin exposures using the National Poison Data System® to describe the clinical course, outcome, and mg/kg dose of metformin exposures in children under six years old. The secondary objective was to describe outcomes in patients divided into safe (≤85 mg/kg reported dose) and caution (>85 mg/kg reported dose) categories. Methods: Using the National Poison Data System®, we analyzed single-substance metformin exposures from 2011–2021 in patients under six years old. We defined two categories of metformin overdose patients: safe (≤85 mg/kg reported dose), who could be managed at home, and caution (>85 mg/kg reported dose), who should be sent to a healthcare facility. Data were summarized with medians with interquartile ranges for continuous variables and percentages for categorical variables. Results: There were 8,762 single-substance metformin exposures reported from 2011–2021. Most patients (6,493, 74.1%) were managed in a non-healthcare setting. Critical care admissions accounted for 73 (3.4%) exposures. For the 1,270 (14.5%) patients who had mg/kg data available, 1,081 (85.1%) were in the safe category with ingestions ≤85 mg/kg, while 189 (14.9%) were in the caution category with ingestions >85 mg/kg. Discussion: Data were limited due to 59.4% of cases missing follow-up information. However, in patients with follow-up information available, most cases were managed on site (74.1%) and only 2.5% of cases required hospitalization. Caution range patients had ten times more admissions (6%) than safe range patients (0.6%) Conclusion: Most exploratory pediatric single-agent metformin exposures were safe and could be managed at home. The ≤85 mg/kg threshold identifies exposures with expected good outcome requiring little to no medical management.