in a Danish clinical trial.
Procollagen type 1 N-terminal peptide (P1NP) plasma concentrations were lower in patients who received either metformin or metformin plus rosiglitazone, Tore Bjerregaard Stage, PhD, a specialist in clinical pharmacology and pharmacy at the University of Southern Denmark, Odense, and his coauthors wrote in Bone.
By contrast, insulin did not appear to influence markers of bone turnover.
Improving glycemic control was associated with increased plasma concentrations of C-terminal telopeptide of collagen (CTx), a marker of bone resorption. However, this finding might reflect “normalization, rather than an abnormal increase in bone resorption,” Dr. Stage and his colleagues wrote.
These findings come from an analysis of the South Danish Diabetes Study, a 2-year, multicenter, randomized, controlled trial including 371 patients with type 2 diabetes. Patients were first randomized to receive short- or long-acting human insulin, then further randomized to metformin plus rosiglitazone, metformin plus placebo, rosiglitazone plus placebo, or two placebos.
Bone turnover markers were assessed at baseline and at 3-, 12-, and 24-month follow-ups.
Dr. Stage and his coinvestigators hoped the analysis would provide insights into how antidiabetic medication might influence bone turnover, potentially helping explain the increased risk of fracture found in patients with type 2 diabetes. “Alterations in bone metabolism due to antidiabetic medication may influence bone metabolism both directly, e.g., by insulin promoting bone formation, and indirectly by improvement of glycemic control,” they wrote.