The Relationship between Serum 25(OH)D, PTH and Calculated HOMA-IR in Overweight Elderly Patients

Background: Vitamin D deficiency or insufficiency was commonly found among adults and particularly overweight elderly patients. It’s controversial on the physiological roles of vitamin D and parathyroid hormone (PTH) in metabolic diseases. We explored the relationship between serum 25-hydroxyvitamin D [25(OH)D], PTH and homeostasis model of assessment for insulin resistance index (HOMA-IR) in overweight elderly patients. Methods: 162 elderly overweight patients were included as the overweight group, and 80 normal-weight elderly in-patients were enrolled as the control group. The concentrations of 25(OH)D, PTH, blood calcium (CA), fasting blood glucose (FBG), and fasting blood insulin (FINS) were determined and HOMA-IR were calculated. Results: The occurrence rate of vitamin D deficiency or insufficiency, primary hypertension, diabetes mellitus type 2 and osteoporosis in the overweight group was significantly higher than that in the control group (p<0.05). The levels of serum PTH, systolic blood pressure (SBP) , diastolic blood pressure (DBP), waist circumference and HOME-IR of the overweight group were significantly higher than that of control group, while serum 25(OH)D and blood calcium were significantly lower (p<0.05). The difference on serum phosphate levels was not significant. Body Mass Index (BMI) was positively correlated with HOMA-IR, r=0.291(F=22.167,p<0.001); Serum 25(OH)D was negatively correlated with HOMA-IR, r=-0.272 (F=19.224,p<0.001); Serum PTH was positively correlated with HOMA-IR, r=0.205 (F=10.4883, p=0.001). Stepwise multiple regression analysis was applied and there was a correlation between HOMA-IR and BMI, 25(OH) D (r=0.353, F=16.984, p<0.001). Conclusion: Vitamin D deficiency or insufficiency and the increase of BMI were significantly associated with insulin resistance in overweight elderly patients.