A Vitamin D-Calcium-Fortified Yogurt Drink Decreased Serum PTH but did not Affect Osteocalcin in Subjects with Type 2 Diabetes

Abstract. Introduction: There is sparse evidence of the effect of vitamin D on bone biomarkers in diabetic patients, and therefore, in a randomized clinical trial, we evaluated the effects of the daily intake of vitamin D, either with or without extra calcium, on selected bone biomarkers. Materials and Methods: Ninety women and men aged 30 - 50 years old with type 2 diabetes were randomly divided into three groups in a double-blind manner. Group 1 (PD), the control group, received a plain yogurt drink. Groups 2 (DD) and 3 (CDD) received 1000 IU vitamin D3, and 1000 IU vitamin D3 plus 500 mg calcium, respectively, via drinking two 250 mL bottles a day of a fortified yogurt drink for twelve weeks. Anthropometric and biochemical assessments were made, including 25(OH), intact parathyroid hormone (iPTH), osteocalcin, and calcium. Results: Although the time and time×group interaction effects on the bone biomarkers were not statistically significant, there was a modest decrease in iPTH concentrations in both DD and CDD groups over twelve weeks. The subgroups with initial vitamin D deficiency/insufficiency in the CDD group had greater and significant decrease in serum iPTH concentrations after twelve weeks of treatment compared to the PD group (- 9.0 ± 21.2 v.s 8.6 ± 21.8 pg/mL, p = 0.042). Conclusion: The improvement in vitamin D status following the daily intake of fortified doogh for twelve weeks was accompanied by a decrement in iPTH, mostly in those subjects with poor initial vitamin D status.