<p><strong>BACKGROUND: </strong>Fasting hypoglycemia is a recognized occurrence among pediatric patients with acute lymphoblastic leukemia (ALL) during maintenance therapy. Existing publications describing this finding are limited to small studies and case reports. Our objective was to determine the incidence of hypoglycemia during maintenance chemotherapy and to investigate the association of age, as well as other potential risk factors, with this outcome in pediatric patients with ALL.</p>

<p><strong>PROCEDURE: </strong>This retrospective cohort study included individuals 1 to 21 years of age with ALL treated with antimetabolite-containing maintenance chemotherapy at a large children's hospital between January 2011 and December 2014. The primary endpoint was time to first documented episode of hypoglycemia during maintenance therapy, defined as single measurement of plasma glucose&nbsp;&lt;60&nbsp;mg/dL. Cox regression was used to evaluate the association with age and identify other potential risk factors.</p>

<p><strong>RESULTS: </strong>We identified 126 eligible patients, of whom 63% were documented as White, non-Hispanic, 28% as non-White, non-Hispanic, and 9% as Hispanic. Twenty-eight children (22%) had documented hypoglycemia during maintenance therapy. Younger age at the start of maintenance and hepatotoxicity documented during chemotherapy prior to maintenance initiation were associated with hypoglycemia (adjusted HR age&nbsp;=&nbsp;0.88; 95% CI, 0.78-0.99; adjusted HR prior hepatotoxicity&nbsp;=&nbsp;3.50; 95% CI, 1.47-8.36).</p>

<p><strong>CONCLUSIONS: </strong>Nearly one quarter of children in our cohort had hypoglycemia documented during maintenance chemotherapy. Younger age at maintenance initiation and hepatotoxicity during chemotherapy prior to maintenance initiation emerged as risk factors. These findings highlight the importance of counseling about the risk of, and monitoring for, hypoglycemia, particularly in young children.</p>