Impaired Insulin Sensitivity and Insulin Secretion in Haemodialysis Patients with and without Secondary Hyperparathyroidism

The aim of our study was to investigate insulin sensitivity and beta cell function in hemodialysis (HD) patients without diabetes. We hypothesized that parathyroid gland function was a determinant of insulin sensitivity and/or beta cell function. The study was a randomized, cross-sectional one and patients were divided into two groups (total 27 patients), Gp.1 being those with relative hypoparathyroidism (iPTH<200 pg/ml) – 9 (33.3%), Gp.2 those with hyperparathyroidism (iPTH≥200 pg/ml) – 18 (66.6%) with Gp.3 (consisting of 43 Zorica Rasic-Milutinovic MD, PhD Chief of Clinical Endocrinology Unit Department of Internal Medicine, Endocrinology Unit Zemun Clinical Hospital, Serbia and Montenegro Email: [email protected] Gordana Perunicic-Pekovic MD, PhD Chief of Clinical Nephrology Unit Department of Internal Medicine, Clinical Nephrology and Hemodialysis Unit, Zemun Clinical Hospital, Serbia and Montenegro Steva Pljesa MD, PhD Prof. of Nephrology, Chief of Nephrology and HD Unit Institute of Social Medicine, Statistics and Medical Research, School of Medicine, University of Belgrade, Serbia and Montenegro Ljiljana Komadina MD, MSc Clinical Nephrology and HD Unit Department of Internal Medicine, Clinical Nephrology and Hemodialysis Unit, Zemun Clinical Hospital, Serbia and Montenegro Zoran Gluvic MD Clinical Endocrinology Unit Department of Internal Medicine, Endocrinology Unit, Zemun Clinical Hospital, Serbia and Montenegro Natasa Milic MD Assistant Lecturer of Statistics and Biomedical Sciences Institute of Social Medicine, Statistics and Medical Research, School of Medicine, University of Belgrade, Serbia and Montenegro healthy subjects acting as controls). Insulin resistance and insulin secretion were calculated from fasting serum insulin and glucose concentrations by the Homeostatic Model Assessment score (HOMA IR and HOMA BETA). The value of HOMA IR (3.28±1.3 for Gp.1, 4.80±2.4 for Gp.2, 1.70±0.8 for Gp.3) as well as the glucose level (5.0±1.0mmol/l in Gp.1, 5.2±0.8mmol/ l in Gp.2, 4.6±0.4mmol/l in Gp.3) was significantly higher in HD patients than in control subjects. Excessive insulin secretion was present in HD patients (as assessed by HOMA BETA) significantly higher only in Gp.1 (p=0.02). HOMA IR was higher in Gp.2 than in Gp.1 (p=0.05), and both groups had higher levels of HOMA IR than the control group (Gp.1/Gp.1 p=0.03; Gp.2/ Gp.3 p=0.00). A positive correlation between HOMA IR and serum iPTH was seen in Gp.2 only (r=0.54, p=0.03). HOMA BETA inversely correlated with Ca x iP product in Gp.1 (r=0.54, p=0.04). The only significant negative correlation between HOMA BETA and age (r= -0.59, p=0.01) was registered in Gp.2. Serum iPTH correlated positively with serum Ca (r= 0.49, p=0.03) in Gp.2. In conclusion, our study demonstrated the presence of a higher level of serum insulin and insulin resistance in HD patients. Serum iPTH directly correlated with the insulin resistance index in hyperparathyroid patients suggesting a possible interaction between PTH and the insulin signaling pathway. Excessive insulin secretion was registered in HD patients, significantly higher only in hypoparathyroid patients. However, beta cells function in both groups of patients was preserved implying relatively good sensitivity of the calcium receptor (CaR) in beta cells.