Metformin Treatment and Gastrointestinal Symptoms in Youth: Findings from a Large Tertiary Care Referral Center.

BACKGROUND Metformin is the only oral therapy for youth with type 2 diabetes, but up to 50% require additional agents within 2 years of diagnosis. Extended-release (XR) metformin formulations may improve adherence and tolerability-- important mediators of treatment response-- but data in youth is lacking. OBJECTIVES To evaluate rates of gastrointestinal (GI) symptoms in patients treated with metformin (SR and XR) and the change in GI symptoms after changes in metformin therapy. METHODS Retrospective chart review of youth with Type 2 or prediabetes seen in a multidisciplinary clinic during 2016-2019. RESULTS Of 488 eligible patients, 41.4% and 21.1% were taking metformin SR and XR respectively, with most (58%, n=178/305) taking a total daily dose of ≥ 1500mg/day. Those not on metformin tended to be younger, leaner, and had lower HbA1cs than those taking metformin, P<0.05. 30% of patients described GI symptoms, most commonly, abdominal pain and diarrhea. There was no difference in GI symptoms in those on SR vs XR (18.3% vs. 14.6%, P=0.41). Among patients who initiated metformin, rates of GI symptoms increased (13% to 33%, P=0.001, n=99), while rates tended to decrease when metformin was discontinued (28% to 12%, P=0.076, n=50). Rates of GI symptoms were unchanged among those that switched from SR to XR metformin (17% vs 14%, P=0.6, n=58). CONCLUSIONS GI symptoms are common in youth with type 2 diabetes taking metformin XR and SR. Adjuncts to mitigate GI symptoms in youth on metformin therapy are needed to improve quality of life and medication adherence. This article is protected by copyright. All rights reserved.