Background Vitamin D may influence many diseases, including type 2 diabetes mellitus.
Patients and Methods We studied serum levels of 25-hydroxyvitamin D (25(OH)D) and associated characteristics in type 2 diabetic outpatients with pharmacologic treatment attended in internal medicine offices in a first-level hospital from Extremadura (Southern Spain).
Results We included a total of 103 patients. Seventy-two patients (69.9%) had serum levels of 25(OH)D lower than 20 ng/mL. There was inverse correlation between serum levels of 25(OH)D and glycosylated hemoglobin (r = −0.74, P = 0.01). In 78 patients without insulin therapy, we found inverse correlation between serum levels of 25(OH)D and fasting serum insulin (r = −0.82, P = 0.001) and Homeostasis Model Assessment–Insulin Resistance (r = −0.51, P < 0.001).
Conclusions Vitamin D deficiency is common in type 2 diabetic patients. There are inverse correlations between vitamin D and metabolic control and insulin resistance.