medwireNews: A randomised controlled trial shows some benefit of metformin treatment in prepubertal children with obesity, but not in pubertal participants.

Among the prepubertal children, the 33 who completed 6 months of treatment with metformin 500 mg twice daily had a body mass index (BMI) z score reduction from 3.4 to 2.6, which was significantly greater than the 4.0 to 3.4 reduction among the 34 prepubertal children who took placebo.

Changes in BMI, weight and waist circumference were not affected by treatment allocation, but the children taking metformin had a significant improvement in insulin sensitivity on the quantitative insulin sensitivity check index (but not on HOMA-IR), relative to those taking placebo.

A total of 73 pubertal children also completed the trial. BMI z score decreased from 3.2 to 2.8 in those taking metformin and from 3.2 to 3.0 in those taking placebo, but the difference was not statistically significant. Neither did treatment allocation influence BMI, weight, waist circumference or insulin sensitivity.

However, Concepción Aguilera (University of Granada, Spain) and study co-authors note that they used the same metformin dose in all study participants, meaning that older participants received a lower dose per kg bodyweight, of 13.4 mg, on average, versus 19.6 mg in the younger children.

In a commentary accompanying the study in Pediatrics, Paul Kaplowitz (George Washington University School of Medicine and the Health Sciences, Washington, DC, USA) describes the 500 mg twice daily dose as “relatively small”, noting that other, smaller studies of metformin in obesity have used doses of up to 1000 mg twice daily, with BMI reductions also seen in pubertal participants.

Kaplowitz concludes that metformin “should not be considered standard of care” for obese children, but suggests it could “have a limited role in treating carefully selected patients with prediabetes and a strong family history of type 2 diabetes, or those who have made a major effort at improving their lifestyle and are frustrated by their inability to lose weight”.

He adds: “In such situations, it is suggested that clinicians push the dose, if tolerated, to the maximum recommended dose of 1000 mg twice daily to take advantage of the important effect of decreased appetite, which likely is a major factor accounting for its variable and modest effect on BMI.”

By Eleanor McDermid

Pediatrics 2017; Advance online publication

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