The influence of intravenous 1,25(OH)2D3 therapy on glucose metabolism in hemodialyzed patients with secondary hyperparathyroidism.

Glucose intolerance, insulin resistance and hyperinsulinemia are common findings in end-stage renal disease patients. Parathormone (PTH) and vitamin D3 are linked with disturbances of glucose metabolism. Glycated hemoglobin (HbA1c) reflects long-term glycemic control. HbA1c is a marker of increased risk of death in diabetic patients but also in general population. The aim of the study was to investigate the influence of 1,25(OH)2D3 therapy on long-term control of glycemia in hemodialyzed (HD) patients with severe secondary hyperparathyroidism (SHP). Eight HD patients with SHP (PTH=1088.6+/-472.2) were given intravenous 1,25(OH)2D3 1-2 microg thrice a week, for 12 weeks (mean dose 4.5 microg/week). At baseline and after 12 weeks fasting blood was sampled for: glucose, insulin, HbA1c, PTH. Insulin/glucose ratio (I/G) was calculated as marker of insulin resistance. Results were compared with 14 healthy volunteers (controls) matched for age, sex and BMI. At baseline I/G was higher in HD vs controls 0.110+/-0.045 vs 0.073+/-0.021 (p = 0.02), and of borderline significance at follow-up (0.106+/-0.053, p=0.05 vs controls). PTH decreased significantly to 506.1+/-646.3 (p<0.02) during therapy. Significant decrease of HbA1c in HD patients was observed (5.84+/-0.40 vs 5.13+/-0.51; p=0.01), while fasting glucose, insulin and I/G did not change significantly. Intravenous 1,25(OH)2D3 therapy is successful, even in patients with severe secondary hyperparathyroidism. Significant decrease in HbA1c with stable insulin concentration may indicate positive impact of intravenous 1,25(OH)2D3 therapy on long-term glucose metabolism.