Hyperinsulinemia is Associated with the Loss of Appendicular Skeletal Muscle Mass at 4.6 Year Follow-up in Older Men and Women

Background & Aims: Homeostasis model assessment as a marker of insulin resistance has been associated with the pronounced loss of appendicular skeletal muscle mass in older adults. In the present study, we hypothesized that hyperinsulinemia as an early predictor of insulin resistance may be associated with the loss of appendicular skeletal muscle mass (ASM).

Methods: This is a cohort study that included 147 well-functioning older men and women subjects who were followed for a period of 4.6 ± 1.8 years. Lean tissue in arm and legs, or ASM, was derived from dual-energy X-ray absorptiometry at baseline with follow-up measurements to obtain the relative change. Hyperinsulinemia was defined empirically at the 75th percentile.

Results: The relative change in ASM was negative and significant throughout the quartiles of fasting insulin levels (p ≤ 0.05); however, the loss of ASM was more pronounced in the later quartiles (-0.7 kg) compared with the relative change in Q1 and Q2 (-0.5 kg and -0.3 kg). The unadjusted analysis indicates a significant association between hyperinsulinemia and the loss of ASM (β = -0.28, 95% CI-0.57-0.009, p = 0.05), an association that remained significant after adjusting for several covariates.

Conclusion: Hyperinsulinemia as an early marker of insulin resistance was associated with the loss of ASM in a cohort study of community-dwelling older men and women subjects without other chronic health conditions. The use of fasting insulin levels >8.4 μU/mL may help clinicians identify individuals in the geriatric population who are at a high risk of loss of appendicular skeletal muscle mass.