Association of vitamin D₃ and its metabolites in patients with and without type 2 diabetes and their relationship to diabetes complications

<h3>Background</h3><p dir="ltr">Epidemiological studies have suggested that vitamin D deficiency is associated with the development of type 2 diabetes (T2DM) and is related to diabetes complications. This study was undertaken to determine the relationship between diabetes complications and cardiovascular risk factors with vitamin D3 and its metabolites: 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), 25-hydroxyvitamin D₃ (25(OH)D₃), 24,25-dihydroxyvitamin D3 (24,25(OH)₂D₃); and 25-hydroxy-3epi-vitamin D₃ (3epi25(OH)D₃).</p><h3>Methods</h3><p dir="ltr">750 Qatari subjects, 460 (61.3%) with and 290 (38.7%) without T2DM, who were not taking vitamin D₃ supplements, participated in this cross-sectional, observational study. Plasma concentrations of vitamin D₃ and its metabolites were measured by liquid chromatography tandem mass spectrometry analysis.</p><h3>Results</h3><p dir="ltr">T2DM subjects had lower concentrations of all vitamin D3 metabolites (<i>p</i> < 0.001) except 3epi25(OH)D₃ (<i>p</i> < 0.071). Males had higher concentrations of all vitamin D3 metabolites (<i>p</i> < 0.001). In the T2DM subjects, lower 25(OH)D3 was associated with retinopathy (<i>p</i> < 0.03) and dyslipidemia (<i>p</i> < 0.04), but not neuropathy or vascular complications; lower 1,25(OH)2D3 was associated with hypertension (<i>p</i> < 0.009), dyslipidemia (<i>p</i> < 0.003) and retinopathy (<i>p</i> < 0.006), and coronary artery disease (<i>p</i> < 0.012), but not neuropathy; lower 24,25(OH)₂D₃concentrations were associated with dyslipidemia alone (p < 0.019); 3epi25(OH)D3 associated with diabetic neuropathy alone (<i>p</i> < 0.029). In nondiabetics, 25(OH)D₃, 1,25(OH)₂D₃ and 24,25(OH)₂D₃ were associated with dyslipidemia (<i>p</i> < 0.001, p < 0.001, p < 0.015, respectively) and lower 1,25(OH)₂D₃ was associated with hypertension (<i>p</i> < 0.001). Spearman’s correlation showed 1,25(OH)₂D₃ to be negatively correlated to age and diabetes duration.</p><h3>Conclusions</h3><p dir="ltr">Different diabetes complications were associated with differing vitamin D parameters, with diabetic retinopathy related to lower 25(OH)D₃ and 1,25(OH)₂D₃ levels, hypertension significantly associated with lower 1,25(OH)₂D₃, while dyslipidemia was associated with lower 25(OH)D₃, 1,25(OH)₂D₃ and 24,25(OH)₂D₃. While 25(OH)D metabolites were lower in females, there was not an exaggeration in complications.</p><h2>Other Information</h2><p dir="ltr">Published in: Therapeutic Advances in Chronic Disease<br>License: <a href="https://creativecommons.org/licenses/by-nc/4.0/" target="_blank">https://creativecommons.org/licenses/by-nc/4.0/</a><br>See article on publisher's website: <a href="https://dx.doi.org/10.1177/2040622320924159" target="_blank">https://dx.doi.org/10.1177/2040622320924159</a></p>