Does metformin treatment influence bone formation in patients with nonalcoholic fatty liver disease?

Antidiabetic drug metformin that improves insulin sensitivity and used in the treatment of nonalcoholic fatty liver disease (NAFLD), may affect the bone health. Our study was designed to investigate a possible effect of metformin on bone formation marker, procollagen type I N-terminal propeptide (P1NP) in patients with NAFLD.In a randomized, placebo controlled study, 63 patients with NAFLD were assigned to one of 2 groups: Group 1 received daily metformin and Group 2 received placebo. Metabolic parameters, insulin resistance markers, and P1NP were determined.Although circulating P1NP levels did not differ significantly between the groups at baseline, at the end of the study, P1NP was significantly lower in patients treated with metformin than in the placebo group (p<0.007). Within-group analysis indicated that P1NP levels significantly decreased (p=0.023) in patients receiving metformin during 4-month follow-up period, while no change in P1NP was observed in placebo group (p=0.359). In general linear model metformin treatment was the only significant independent predictor of endpoint P1NP.Metformin treatment was associated with decrease in P1NP levels in patients with NAFLD. The effect on P1NP was independent of glucose lowering effect and caused from exposure to metformin per se.