Dipeptidyl peptidase-4 inhibitors and bone metabolism: is vitamin D the link?

Abstract AIMS: Dipeptidyl peptidase-4 inhibitors (DPP4-Is) represent a promising class of agents for type 2 diabetes treatment. Experimental models and clinical studies have reported positive effects of DPP4-Is on bone; however, how DPP4-Is positively impact bone homeostasis in humans remains an unanswered question. Aim of this study investigated the relationship between treatment with DPP4-Is and vitamin D balance in patients with type 2 diabetes. METHODS: This is a cross-sectional study. A total of 295 consecutive individuals with type 2 diabetes referring to our diabetes outpatient clinics were enrolled; among them, 53 % were in treatment with DPP4-Is. Metabolic profile and routine biochemistry were assessed by standard methods; serum 25(OH) vitamin D levels [25(OH)D] were measured by colorimetric method (LAISON, DiaSorin). RESULTS: DPP4-Is-treated participants had significantly higher serum 25(OH)D levels then those undertaking other antidiabetic therapies (18.4 ± 10.7 vs. 14.9 ± 8.6 ng/ml, p = 0.004); this association persisted after adjusting for all major confounders. Increased 25(OH)D concentrations also correlated with the duration of DPP4-Is treatment and with a stronger DPP4 inhibitory activity. CONCLUSIONS: DPP4-Is treatment is associated with improved vitamin D balance in people with type 2 diabetes; our findings suggest that vitamin D may underlie the link between DPP4-Is and bone metabolism.