Clinical characteristics of subclinical carotid atherosclerosis in middle-aged and elderly populations with different glucose metabolism statuses: a cross-sectional study

Background Subclinical carotid atherosclerosis (SCAS) is linked to cardiovascular events, yet its characteristics across various glucose metabolism statuses remain unclear. This study investigated SCAS prevalence and its association with dysglycemia in a community-dwelling population. Methods In this cross-sectional study (September–December 2021, Beijing), 4,964 middle-aged and elderly residents underwent 75 g oral glucose tolerance tests and were categorized into normal glucose tolerance (NGT), prediabetes [including isolated impaired fasting glucose [IFG], isolated impaired glucose tolerance [IGT], and combined IFG + IGT], and new-onset diabetes mellitus (DM). Standardized carotid ultrasonography assessed carotid intima-media thickness (CIMT) and plaque presence. Multivariable logistic regression was used to identify factors associated with SCAS in the whole cohort and in the prediabetic subgroup, with adjustment for age, sex, blood pressure, body mass index, and lipid profiles. Results The cohort comprised 2,224 NGT, 2,022 prediabetes (758 IFG, 569 IGT, 695 mixed), and 718 DM participants. Anthropometric and metabolic parameters progressively worsened with increasing glucose dysregulation severity. SCAS prevalence was highest in the DM group (70.5%), followed by prediabetes (66.8%) and NGT (62.2%) ( p < 0.05). Within the prediabetic cohort, SCAS was significantly more prevalent in the IGT group than the IFG group (63.5% vs. 55.8%, p < 0.05). After full adjustment, compared with NGT, both prediabetes (OR = 1.28, 95% CI: 1.10–1.49) and new-onset DM (OR = 1.52, 95% CI: 1.25–1.85) remained independently associated with SCAS (both p < 0.01). In the prediabetic subgroup, factors independently associated with SCAS included age, sex, 2 h postprandial glucose, total cholesterol, and HDL-C (protective). Conclusion The prevalence of SCAS varies significantly across glucose metabolism statuses. Both new-onset diabetes and prediabetes—particularly the IGT phenotype—are closely associated with a higher burden of SCAS, independent of traditional cardiovascular risk factors. These findings provide a rationale for evaluating early screening strategies in future prospective studies, but prospective cohort studies are needed to establish causal relationships and to determine the clinical implications.