White blood cell counts, insulin resistance, vitamin D levels and sarcopenia in Korean elderly men

Abstract

Sarcopenia is a major determinant of frailty, disability and mortality in the elderly. Whether low-grade inflammation, insulin resistance and vitamin D are independently associated with sarcopenia remains unclear. In our study, sarcopenia was defined as an appendicular skeletal muscle mass divided by height squared (ASM/Ht²) that was <2 SD below the normal means for young adults. Insulin resistance was estimated using the homeostasis model assessment of insulin resistance (HOMA-IR) index [(insulin (IU/mL) × fasting glucose (mg/dL)/18)/22.5]. Data of white blood cell counts and serum 25-hydroxyvitamin D (25-(OH)D) levels were collected in the second and third year (2008–2009) of Fourth Korean National Health and Nutrition Examination Survey (KNHANES IV). The results showed that the prevalence of sarcopenia in Korean elderly men aged more than 65 years was 11.2%. ASM/Ht² were positively associated with vitamin D levels, but negatively associated with white blood cell counts and HOMA-IR by multiple regression analysis. After adjustment for covariables, sarcopenia was associated with the highest quartile of WBC counts (OR = 2.93, 95% CI = 1.21–7.14) and the highest quartile of serum vitamin D levels (OR = 0.38, 95% CI = 0.15–0.95). In conclusion, the study findings suggest that higher WBC counts and lower vitamin D levels are independently associated with the presence of sarcopenia in community-dwelling elderly men. They also provide a basis for further studies of the complex immune-endocrine network in sarcopenia.

Keywords:

• Aged
• insulin resistance
• leukocytes
• sarcopenia
• vitamin D

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.