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Impact of metformin on bone turnover markers: a systematic review and meta-analysis of clinical trials

Heidari M, Mirdamadi N, Khashayar P, Tabatabaei-Malazy O, Golabchi M, Khashayar P

Archives of osteoporosis, 2026

Abstract

UNLABELLED: Metformin is widely used for diabetes, but its effects on bone health are uncertain. This meta-analysis study found that it reduces markers of both bone loss and bone formation. It is still unclear whether this benefits or harms bones long term, highlighting the need for larger, longer clinical studies.

PURPOSE: Metformin is a widely used antidiabetic drug that has shown potential effects on bone metabolism. However, its impact on bone turnover markers remains unclear. This systematic review and meta-analysis aimed to assess this effect.

METHODS: A comprehensive search was conducted across PubMed, Scopus, Embase, Web of Science, and Cochrane Library databases, identifying clinical trials published up to February 04, 2026, that evaluated the effects of metformin on validated bone turnover markers. The quality and risk of bias were assessed using the Modified Jadad Scale, and Cochrane Collaboration's risk of bias tool, respectively. A random-effects meta-analysis was performed to estimate the standardized mean difference (SMD) with a 95% confidence interval.

RESULTS: Fourteen studies met the inclusion criteria, involving diabetic and non-diabetic populations. Metformin significantly reduced both bone resorption, bone formation markers (SMD: -1.28 [95% CI: -2.03, -0.52], I2 = 99.33%), and (-0.18 [-0.28, -0.08], I2 = 67.78%), respectively. These findings suggest a pattern consistent with reduced bone turnover rather than selective modulation of either bone resorption…

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