Glycemic variability and muscle loss in elderly type 2 diabetes: insights from continuous glucose monitoring and chest CT in 303 patients.

PURPOSE: Sarcopenia is common among older adults with type 2 diabetes mellitus (T2DM). Although chronic hyperglycemia is known to contribute to muscle loss, it remains unclear whether glucose fluctuations-independent of average glucose levels-also play a role. This study aimed to investigate the association between glucose fluctuation and pectoralis muscle mass in elderly patients with T2DM.

METHODS

This retrospective cross-sectional study included 303 elderly patients with T2DM who underwent continuous glucose monitoring and chest CT between October 2022 and December 2025. Glycemic variability was assessed using several metrics: coefficient of variation (CV), standard deviation (SD), mean amplitude of glycemic excursions (MAGE), mean of daily differences, time in range, time above range, time below range (TBR), and mean blood glucose. Pectoralis muscle index (PMI) was measured from CT images at the T4 vertebra level. Multivariable linear regression, subgroup analyses, and sensitivity analyses were performed.

RESULTS

Four glycemic variability indicators-CV, SD, MAGE, and TBR-were independently associated with lower PMI after adjusting for confounders (all P < 0.05). Among these, CV explained the largest proportion of PMI variance (adjusted R² = 0.22), followed by TBR (0.21), SD (0.20), and MAGE (0.19). A linear dose-response relationship was observed between CV and PMI (P for trend < 0.001). The inverse association was stronger in patients with diabetes duration ≥ 10 years (β = -0.18, P < 0.001) and those with BMI < 24 kg/m² (β = -0.18, P < 0.001), with significant interactions for both subgroups (P = 0.022 and 0.027, respectively). Sensitivity analyses confirmed the robustness of these findings.

CONCLUSIONS

Greater glycemic variability is independently associated with lower pectoralis muscle mass in elderly patients with T2DM, especially among those with longer disease duration or normal body weight. Stabilizing glucose fluctuations may be an important consideration for preserving muscle mass in this population.