To assess the effect of cholecalciferol therapy at various doses on glucose metabolism in patients with prediabetes.

The study included 65 women aged 42 to 64 years with prediabetes not taking vitamin D and without diseases affecting its metabolism. Patients were randomized into two groups: group 1 (n=30) received cholecalciferol 500 IU/day, group 2 (n=25) – 5000 IU/day for 4 months. Anthropometric data, comorbidities, and concomitant medications were assessed. Before and after 4 months of cholecalciferol therapy all patients underwent a standard oral glucose tolerance test with venous blood sampling at points 0’ and 120’. The indices of insulin resistance (HOMA-IR), insulin sensitivity (ISI-0,120), functional activity of b-cells (HOMA-B) and Glycated hemoglobin (HbA1c) were calculated.

After 4 months Reduction in HbA1c (p=0.001) and plasma glucose at points 60′ (p=0.04) and 120′ (p=0.04), increase in insulin level at point 120′ (p=0.03) and gain in HOMA-B index (25.3%) at the end of the study were observed only in patients takin 5000 IU of cholecalciferol daily. After 4 months of therapy in 13 women (50%) from group 2 glucose and HbA1c levels corresponded to normal values while only 2 patients from group 1 had these parameters within normal ranges (p=0.001).

Treatment with 5000 IU of cholecalciferol per day for 4 months is associated with increase in glucose metabolism improvement in women with prediabetes. Key words: prediabetes, vitamin D, glucose, cholecalciferol