Aim To assess vitamin B12 levels in children with obesity and analyze the association with obesity severity, complications and treatment methods. Methods A retrospective analysis of data of 500 patients with obesity (51.6% boys) was performed, mean age was 13.1 years (range 1.7–17.9), mean BMI Z-score was 2.17 (SD 0.42). Anthropometric data, body composition, blood pressure, lipid profile, glycated hemoglobin and liver enzymes were evaluated. Statistical analysis included Spearman correlation and Mann–Whitney U test (α = 0.05). Results Dyslipidemia was found in 45.8%, hypertension in 14.8%, elevated liver enzymes in 19.8%. 12% received metformin. Median B12 was 407 pg/ml (range: 161–1168). No correlation was found between B12 and BMI Z-score, body fat percentage, high-density lipoprotein, triglycerides, gamma-glutamyl transferase or glycated hemoglobin. Negative correlation was found with creatinine (p < 0.001) and homeostatic model assessment for insulin resistance (p < 0.001); positive correlation was found with total cholesterol (p = 0.012), low-density lipoprotein (p = 0.029), alanine aminotransferase (p = 0.002) and aspartate aminotransferase (p < 0.001). Metformin users showed significantly lower B12 (398 vs 410 pg/ml, p = 0.043). Conclusion: Children with obesity do not exhibit vitamin B12 deficiency. Obesity severity is not associated with B12 changes. Insulin resistance (especially metformin-treated) may be associated with reduced B12 levels. Pediatric patients with uncomplicated obesity do not require regular vitamin B12 monitoring, whereas it appears necessary in patients on metformin therapy. <Table Float="No" ID="Taba"> <tgroup cols="2"> <colspec align="left" colname="c1" colnum="1" /> <colspec align="left" colname="c2" colnum="2" /> <tbody> <row> <entry align="left" nameend="c2" namest="c1"> What is Known – What is New: • The limited literature on vitamin B12 levels in children with obesity reports a negative correlation with obesity severity which is inconsistent with observations from our center performing metabolic assessments on over 500 children with obesity annually. • Our study demonstrates that children with obesity do not exhibit vitamin B12 deficiency and obesity severity is not associated with B12 changes. However, metformin treatment may be associated with reduced B12 levels. • Pediatric patients with uncomplicated obesity do not require regular vitamin B12 monitoring, whereas it appears reasonable in patients on metformin therapy. </entry> </row> </tbody> </tgroup> </Table>

Investigating vitamin B12 levels in children with obesity: the role of metformin

期刊论文
发表日期：

2026年3月18日

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A. Iwańska,
D. Goncerz,
M. Ahmed,
R. Aoun,
A. Kozioł-Kozakowska,
E. Szczudlik,
A. Stępniewska,
M. Wójcik,
J. B. Starzyk

摘要

Aim

To assess vitamin B12 levels in children with obesity and analyze the association with obesity severity, complications and treatment methods.

Methods

A retrospective analysis of data of 500 patients with obesity (51.6% boys) was performed, mean age was 13.1 years (range 1.7–17.9), mean BMI Z-score was 2.17 (SD 0.42). Anthropometric data, body composition, blood pressure, lipid profile, glycated hemoglobin and liver enzymes were evaluated. Statistical analysis included Spearman correlation and Mann–Whitney U test (α = 0.05).

Results

Dyslipidemia was found in 45.8%, hypertension in 14.8%, elevated liver enzymes in 19.8%. 12% received metformin. Median B12 was 407 pg/ml (range: 161–1168). No correlation was found between B12 and BMI Z-score, body fat percentage, high-density lipoprotein, triglycerides, gamma-glutamyl transferase or glycated hemoglobin. Negative correlation was found with creatinine (p < 0.001) and homeostatic model assessment for insulin resistance (p < 0.001); positive correlation was found with total cholesterol (p = 0.012), low-density lipoprotein (p = 0.029), alanine aminotransferase (p = 0.002) and aspartate aminotransferase (p < 0.001). Metformin users showed significantly lower B12 (398 vs 410 pg/ml, p = 0.043).

Conclusion: Children with obesity do not exhibit vitamin B12 deficiency. Obesity severity is not associated with B12 changes. Insulin resistance (especially metformin-treated) may be associated with reduced B12 levels. Pediatric patients with uncomplicated obesity do not require regular vitamin B12 monitoring, whereas it appears necessary in patients on metformin therapy.

What is Known – What is New:

• The limited literature on vitamin B12 levels in children with obesity reports a negative correlation with obesity severity which is inconsistent with observations from our center performing metabolic assessments on over 500 children with obesity annually.

• Our study demonstrates that children with obesity do not exhibit vitamin B12 deficiency and obesity severity is not associated with B12 changes. However, metformin treatment may be associated with reduced B12 levels.

• Pediatric patients with uncomplicated obesity do not require regular vitamin B12 monitoring, whereas it appears reasonable in patients on metformin therapy.