Author(s): WANG, H., LU, Y., YAN, H., FANG, Z. , Institution: BEIJING RESEARCH INSTITUTE OF SPORTS SCIENCE, Country: CHINA, Abstract-ID: 1438

INTRODUCTION:
Aging is accompanied by progressive impairments in glucose regulation, increasing the risk of transition from normoglycemia to prediabetes and diabetes. Exercise improves glycemic control; however, the physiological responsiveness to exercise may differ according to baseline metabolic status. In particular, alterations in short-chain fatty acids (SCFAs) and circulating amino acids may be implicated in exercise-mediated metabolic regulation. This study investigated the differential metabolic adaptations to a 12-week brisk walking intervention in older adults with normoglycemia, prediabetes, and diabetes.
METHODS:
Older participants were classified by oral glucose tolerance test into three groups: normoglycemic control (CG, n = 39), prediabetes (PDM, n = 19), and diabetes (DM, n = 15). Baseline assessments included glycemic biomarkers (e.g., HbA1c, 2-hour glucose), inflammatory marker (IL-6), body composition (waist-to-hip ratio, WHR), and physical function (6-meter walk speed). Targeted metabolomics was performed to quantify short-chain fatty acids (SCFAs) and amino acids. All participants completed a 12-week supervised brisk walking program (45 min/session, three sessions/week, 40–60% heart rate reserve) while maintaining habitual lifestyle patterns. All measurements were repeated post-intervention. Pre–post changes (Δ values) were calculated and compared among groups.
RESULTS:
After 12 weeks, glycemic parameters showed overall improvement across groups. In the CG group, HbA1c decreased significantly. In the PDM group, both HbA1c and 2-hour glucose were significantly reduced, accompanied by a significant decrease in IL-6 and WHR. In the DM group, only 2-hour glucose decreased significantly. Comparison of Δ values indicated that HbA1c reduction was greatest in the PDM group. Physical function improved in all three groups without significant between-group differences. Metabolomic analysis revealed common patterns across groups, including increased valerate and caproate and decreased branched-chain and aromatic amino acids. Propionate increased exclusively in the PDM group, whereas acetate decreased only in the DM group. In the correlation analysis of PDM group, propionate, valerate, and caproate were inversely correlated with glycemic indices (including 2-hour glucose), while branched-chain amino acids were positively correlated with these parameters.
CONCLUSION:
A 12-week brisk walking intervention effectively improved glycemic control in older adults, with the most pronounced benefits observed in individuals with prediabetes. Improvements were accompanied by favorable shifts in metabolite profiles, characterized by increased SCFAs and reduced amino acids associated with metabolic dysfunction. Propionate may represent a key metabolite linked to exercise-induced glycemic improvement in prediabetes. These findings suggest that moderate-intensity walking is a practical and effective strategy for early metabolic intervention in older populations, particularly in prediabetic stage.