The effect of 25-hydroxyvitamin D levels on QT interval duration and dispersion in type 2 diabetic patients

AIM: To assess the relationship between corrected QT (QTc) interval and vitamin 25-hydroxyvitamin D levels (25-OHD) deficiency in type 2 diabetic patients. METHODS: The study included 253 patients with type 2 diabetes and 170 age-matched controls treated between October and December 2013. QTc duration and QTc dispersion were measured on ECG recordings and 25-OHD, calcium, phosphorus, and blood glucose levels were determined. RESULTS: Patients with diabetes had significantly longer QTc duration and QTc dispersion than controls (P<0.001 and P<0.001 respectively). Diabetic patients with prolonged QTc duration were older and had longer diabetes duration and higher HbA1c levels than patients with normal QTc interval. They significantly more frequently had 25-OHD deficiency (P<0.001), but had similar calcium and phosphorus levels. Diabetic patients with prolonged QTc dispersion were of similar age and had similar diabetes duration and HbA1c levels as patients with normal QTc dispersion. They significantly more frequently had 25-OHD deficiency (P=0.010), but had similar calcium and phosphorus levels. CONCLUSION: This study showed prolonged QTc duration and QTc dispersion in patients with type 2 diabetes, especially those with 25-OHD deficiency.