GC and vitamin D deficiency: Using the Global Consensus Recommendations on Prevention and Management of Nutritional Rickets, there was no significant difference in the prevalence of deficient, insufficient, and optimal 25(OH) vitamin D. Further, levels of vitamin D-binding protein were significantly decreased in the deficient vitamin D group compared to the insufficient vitamin D group and the optimal vitamin D group (p = 0.007), according to the 2011 Endocrine Clinical Society Practice Guidelines for vitamin D deficiency (Figure 1).