Objective: This study aimed to assess the early results of the effect of antidiabetic drugs on serum 25-hydroxyvitamin D (25(OH)D) level in patients with type 2 diabetes mellitus (T2DM).
Methods: Thirty-five patients with T2DM having vitamin D deficiency (<20 ng/ml) or insufficiency (<30 ng/ml) were included. They were divided into 5 groups according to the drug therapy (metformin alone (n=9), metformin in combination with insulin (n=6), or sulphonylurea (n=4), or DPP-4 inhibitor (n=7), or SGLT-2 inhibitor (n=9)). All participants were given daily supplementation of 2000 IU vitamin D3. Serum levels of phosphate, ionized calcium, parathyroid hormone (PTH), 25-hydroxyvitamin D (25(OH)D), HbA1c were measured at baseline and 12 weeks after the aforementioned supplementation, for comparison purpose. Serum level of 25(OH)D was measured by mass spectrometry method using Cobas e411. Statistical analysis included descriptive statistics (percentage, mean and median) and multiple comparisons by non-parametric tests.
Results: The mean age of the patients was 48.32±19.83 (3775) years. There were 17 men and 18 women. The median 25(OH)D level in serum (mean±S.D. 14.7±7.28 (3.029.8) ng/ml) was low in all participants. When compared the 5 groups according to therapy, there was no significant difference in the levels of serum phosphate, ionized calcium, PTH, 25(OH)D and HbA1c. However, in the dapagliflosin group the level of phosphorus (1.65±0.06 mmol/l) was significantly higher than the metformin alone group (1.19 mmol/l±0.06) (P=0.002); the serum 25(OH)D levels were similar (15.12±7.13 ng/ml and 14.8±7.14 ng/ml respectively) (P>0.05).
Conclusions: Preliminary results show that patients on dapagliflozin therapy have higher serum phosphate levels compared to patients on metformin therapy.There is no meaningful association between 25(OH)D level and type of T2DM therapy. However, due to the limited number of participants and short duration of the study potential effects on clinical outcomes still remain to be answered. These should be assessed in future studies with larger sample sizes and longer follow-up.
18 May 2019 - 21 May 2019