Background: Orthostasis is more common in people with diabetes, especially the elderly, and vitamin D receptors are present in vascular smooth muscles, endothelium, and cardiac cells, which may influence cardiac as well as motor responses during orthostasis. This work aimed for evaluation of the vitamin D status and its correlation with orthostatic hypotension among diabetic patients.

Methods: This pospective cohort study was carried out on 106 type 2 diabetic patients from internal medicine department, at Zagazig University Hospital. Patients were split into the following groups: Group I: cases with vitamin D deficiency(n=50), and Group II: cases with vitamin D insufficiency (n=56). Vitamin D level was assessed using ELISA, and the assessment of orthostatic hypotension via measurement of Blood pressure (BP) after 15 minutes of rest in the supine position.

Results: Both HbA1c and 25(OH) D levels showed high statistically significant differences between group II compared to group I (P = 0.001 for each). A statistically significant difference was found between pre- and post-vitamin D supplementation (P=0.001). Group I had a higher significant orthostatic hypotension than Group II did (P = 0.001). There was an improvement in orthostatic hypotension among the studied groups after vitamin D supplementation. At a cut-off value ≤72.1 nmol/L vitamin D can predict orthostatic hypotension in diabetic patients with a specificity of 97.83%, Sensitivity of 100%, PPV of 93.3%, and NPV of 100%.

Conclusion: Orthostatic hypotension and vitamin D levels were found to be strongly correlated among diabetic patients