Aim of the studyTo assess serum 25-hydroxyvitamin D3 level and insulin resistance (IR) in hepatitis B virus (HBV) patients compared with controls and to evaluate the correlation with HBV viral load, severity of liver disease and degree of liver fibrosis.Material and methodsA case-control study. Sixty HBV patients and 60 controls were enrolled. Chemiluminescence was used to determine 25-hydroxyvitamin D3 levels. Insulin resistance was evaluated using the homeostasis model assessment method. Polymerase chain reaction was used to quantify HBV viral loads. Severity of liver disease was assessed by Child-Pugh scores. Transient elastography was used to evaluate the degree of liver fibrosis.Results25-Hydroxyvitamin D3 deficiency is more prevalent among HBV patients compared to controls. 25-Hydroxyvitamin D3 levels declined considerably as viral load rose (p < 0.001). 25-Hydroxyvitamin D3 level declined as liver fibrosis progressed (34.0 ±0.0 ng/ml in F1 vs. 12.67 ±8.0 ng/ml in F4) and the severity of the disease increased (22.75 ±6.36 ng/ml in Child A vs. 5.50 ±0.58 ng/ml in Child C). Insulin resistance is more prevalent among HBV patients compared to controls and it appeared to deteriorate progressively with boosting of the viral load, degree of fibrosis and severity of liver disease (p < 0.001).ConclusionsHBV patients had significantly lower 25-hydroxyvitamin D3 levels compared to healthy individuals and HBV infection is associated with IR. 25-Hydroxyvitamin D3 deficiency and IR were associated with HBV viral loads, severity of liver disease, and degree of liver fibrosis.