Skeletal muscle health and the development of prediabetes in middle-aged and older adults: mediated by inflammation and lipid indices.

AIMS: This study aims to examine the effect of relative muscle strength (RMS) on the progression to diabetes or regression to normoglycemia in individuals with prediabetes.

METHODS

Data were sourced from the China Health and Retirement Longitudinal Study (CHARLS), which followed 3250 individuals aged ≥45 years with prediabetes. RMS was calculated as the ratio of grip to appendicular skeletal muscle mass (ASM). Multinomial logistic regression was used to assess the association of RMS with subsequent glycemic transitions, including regression to normoglycemia, persistence of prediabetes, and progression to diabetes. Mediation analysis explored the role of inflammation and lipid profiles in this association.

RESULTS

During the follow-up period, 1953 participants remained in the prediabetes stage, 698 reverted to normoglycemia, and 599 progressed to diabetes. Participants regressing to normoglycemia exhibited significantly higher RMS than those remaining prediabetic [M (IQR): 2.25 (1.85, 2.62) vs. 2.16 (1.78, 2.55)], whereas those who progressed to diabetes showed lower RMS [1.97 (1.61, 2.32)]. Compared to the low RMS group, the OR (95% CI) for the high RMS group was 0.49(0.38, 0.64). Mediation analysis showed that high-density lipoprotein (HDL), triglycerides (TG), and C-reactive protein (CRP) partially mediated the effect between RMS and prediabetes progression, accounting for 14.47%, 4.41%, and 0.21% of the overall effect, respectively.

CONCLUSIONS

Higher RMS independently protects against prediabetes progression and may aid regression, mediated by HDL, TG, and CRP.