Vitamin D3 supplementation improves serum SFRP5 and Wnt5a levels in patients with type 2 diabetes: A randomized, double-blind, placebo-controlled trial.

To explore the effect of vitamin D3 on novel serum adipokines, secreted frizzled-related protein 5 (SFRP5) and Wingless-Type MMTV Integration Site Family Member 5a (Wnt5a) levels in Type 2 Diabetes Mellitus (T2DM) patients. Forty patients (16 women and 24 men) with type 2 diabetes participated in this double-blind, randomized, placebo-controlled clinical trial study. Participants were randomly assigned to receive 4000 IU vitamin D (n = 20) or placebo (n = 20) daily for 2 months. Anthropometric indices, fasting blood glucose (FBS), hemoglobin A1c (HbA1c), insulin, serum tumor necrosis factor (TNF)-α, Wnt5a, SFRP5, physical activity, lipid profile, dietary intake, and serum calcidiol were assessed at the baseline and after 8 weeks. In the group receiving Vitamin D, a significant increase in Calicidiol (15.03 ± 10.44 vs. 27.33 ± 11.2 ng/dl; P = < 0.001), SFRP5 (3.6 ± 0.46 vs. 3.98 ± 0.59 ng/ml; P = 0.01), and Wnt5a (0.33 ± 0.129 vs. 0.29 ± 0.047; P = 0.03) was observed. After two months supplementation, there were significant between-group differences in Calicidiol (27.33 ± 11.2 vs. 17.9 ± 12.95 ng/dl; P = 0.01), TNF-α (89.22 ± 34.28 vs. 164.93 ± 120.45 ng/ml; P = 0.006), Wnt5a (0.29 ± 0.047 vs. 0.33 ± 0.09; P = 0.04), and HbA1c (6.6 ± 0.96 % vs. 7.64 ± 1.15 %; = 0.002). Moreover, the net changes (end - baseline) of Calicidiol (P = < 0.001), SFRP5 (P = 0.04), Wnt5a (P = 0.005), TNF-α (P = 0.01), insulin (P = 0.03), and QUICKI (P = 0.01) was significant between the groups. There were no significant effects on FBS and homeostasis model of assessment-estimated insulin resistance (HOMA-IR). 8 weeks of vitamin D3 supplementation for patients with type 2 diabetes may increase serum anti-inflammatory adipokine SFRP5 but decrease serum pro-inflammatory Wnt5a and TNF-α.