Abstract

Objective: Metformin is widely used in pediatric obesity to improve insulin resistance. This study aimed to examine the association between metformin use and metabolic outcomes in adolescents with obesity, applying longitudinal follow-up and oral glucose tolerance test (OGTT)-based analyses to address this question.

Materials and Methods: Ninety-six adolescents with obesity (32 metformin-treated, 64 receiving lifestyle modification alone) were evaluated at baseline, 6 months, and 12 months. Anthropometric, biochemical, and OGTT-derived glucose and insulin parameters were analyzed.

Results: At baseline, the metformin group had significantly higher BMI (p=0.005), fasting insulin (p=0.007), HOMA-IR (p=0.002), HbA1c (p<0.001) and uric acid (p=0.008), indicating greater metabolic severity. OGTT analysis demonstrated comparable glucose levels but markedly elevated insulin responses across all time points in the metformin group, consistent with a hyperinsulinemic state. Both groups showed significant improvement in anthropometric and metabolic parameters at 6 months; however, partial deterioration was observed at 12 months. In adjusted analyses, metformin use remained associated with higher fasting insulin (p=0.004) and HOMA-IR (p=0.003) at 6 months, but not at 12 months (p=0.080 and p=0.070, respectively). Among patients not receiving metformin, elevated OGTT 1-hour glucose (>155 mg/dL) demonstrated a borderline association with higher BMI at 6 months (p=0.078).

Conclusion: In this observational cohort, adolescents treated with metformin represented a more severe metabolic phenotype at baseline. Although early (6-month) improvements were evident in both groups, these effects were not sustained at 12 months. No significant association was observed between metformin use and independent alteration of long-term metabolic trajectory beyond lifestyle modification alone. These findings suggest that metformin prescription reflects baseline disease severity; however, the observational design precludes definitive conclusions regarding treatment efficacy, and prospective randomized studies are needed.

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Copyright © 2026 The Author(s). This is an open access article distributed under the Creative Commons Attribution License (CC BY), which permits unrestricted use, distribution, and reproduction in any medium or format, provided the original work is properly cited.

How to cite

1.
Kızılcan Çetin S, Buyukyilmaz G, Kelestemur E, Demirtas S, Sengil HN, Gurbuz F. Metformin treatment in pediatric obesity: A real-world experience showing pronounced 6-month improvement but limited long-term sustainability. Turk J Pediatr Dis. 2026;Early View:1-7. https://doi.org/10.12956/TJPD.2026.1360