Relationship of insulin resistance with serum 25-hydroxyvitamin D levels and arterial stiffness in elderly patients

Objective To explore the relationship of insulin resistance with serum 25-hydroxyvitamin D levels and arterial stiffness in elderly patients. Methods A total of 162 elderly inpatients (aged 60 years or over) were recruited from 2012 to 2014. Levels of fasting serum insulin, fasting serum glucose, creatinine and vitamin D were determined. Insulin resistance (IR) was evaluated by the homeostasis model assessment of insulin resistance (HOMA-IR). The patients were divided into the following three groups according to HOMA-IR: the low IR group with HOMA-IR less than 2 (n=78), the median IR group with HOMA-IR between 2 and 6 (n=43), and the high IR group with HOMA-IR greater than 6 (n=41). Arterial stiffness was assessed by carotid-femoral pulse wave velocity (cfPWV). Arterial stiffness and serum vitamin D levels were compared among the three groups. Results cfPWV was increased and the serum 25-hydroxyvitamin D level was decreased in the high insulin resistance group compared with the low insulin resistance group〔(13.2±5.7) μg/L vs. (17.8±6.2) μg/L, (14.3±5.2) m/s vs. (11.9±3.0) m/s〕. Multiple liner regression analysis showed that IR was negatively correlated with the serum 25-hydroxyvitamin D level (r=-0.63, P<0.05) and positively correlated with arterial stiffness (r=0.45, P<0.05) after adjustment for age, sex and other confounders. Conclusions Elderly patients with high insulin resistance may have lower levels of serum vitamin D and higher arterial stiffness. Key words: Insulin resistance; Vitamin D deficiency; Arteriosclerosis