Effect of Vitamin D on Thyroid Function Among Diabetic Patients

Abstract

This study evaluated the correlation between vitamin D levels and thyroid function in a diabetic population (HbA1c = 6.5%) from southern Saudi Arabia, involving 2918 participants (54.9% of females and 45.1% of males). The results indicated that 18% were vitamin D deficient, 69.4% were vitamin D insufficient, and 12.7% were vitamin D sufficient. Gender-specific analyses revealed that 10% of females and 8% of males were vitamin D deficient. Among those with primary hypothyroidism, 0.9% were vitamin D deficient, while for subclinical hypothyroidism, 7.2% were vitamin D deficient. For primary hyperthyroidism, only 0.3% were vitamin D deficient, with no deficiencies in subclinical hyperthyroidism. A partial correlation analysis, controlling for age and gender, showed a significant negative correlation between vitamin D and thyroid hormone levels (r² = –0.328). Multinomial regression indicated that individuals with vitamin D deficiency had a 1.511 times higher risk of subclinical hypothyroidism. Those with vitamin D insufficiency showed an increased risk for both primary (Exp(B) = 1.189) and subclinical hypothyroidism (Exp(B) = 0.719). In conclusion, this study highlights a significant link between vitamin D levels and thyroid function in diabetics, with deficiency and insufficiency associated with higher risks of specific thyroid disorders.