Abstract Body: Introduction
Prediabetes, characterized by elevated fasting blood glucose (FBG), impaired glucose tolerance, or increased glycated hemoglobin (HbA1c), is associated with heightened cardiovascular disease (CVD) risk. This study aimed to assess macro- and microvascular alterations in individuals with prediabetes.

Hypothesis
We hypothesized that impaired vascular function correlates with greater cardiometabolic risk among adults with prediabetes.

Methods
We conducted a cross-sectional analysis using preliminary data from an ongoing clinical study assessing vascular function and cardiometabolic risk in adults with prediabetes. Measures included blood pressure, arterial stiffness, endothelial microvascular function, and cutaneous vascular conductance (CVC), assessed via Laser-Doppler flowmetry with local heating in the forearm. Skin blood flow was measured at baseline (33°C) and local heating to 42°C. Data were normalized as a percent of maximal vasodilation (%CVC_max). FBG, HbA1c, and anthropometrics were recorded. Normality was assessed via Shapiro-Wilk. Pearson correlation or Spearman’s rank correlation was applied based on distribution. Significance was defined as P < 0.05.

Results
To date, 13 participants (62% female, age: 55 [47–59] years) have been analyzed. Mean arterial pressure (MAP), FBG, and HbA1c were 91 ± 10 mmHg, 107.5 ± 6.9 mg/dL, and 5.5 ± 0.2%, respectively. Body fat percentage (36.5 ± 7.9%) had a strong inverse correlation with %CVC_max at 33° C (8.5 [6.7 – 11.7]; ρ = -0.76, P = 0.002). Age and HbA1c were inversely correlated with %CVC_max at 42° C (88.7 [84.4 – 94.4]; ρ = -0.554, P = 0.05 and ρ = -0.546, P = 0.05, respectively). Augmentation index (AIx, 27.7 ± 13.6%), a measure of arterial stiffness, was correlated with age (ρ = 0.715, P = 0.009) but inversely correlated with HbA1c (r = -0.577, P = 0.049). Similarly, the natural log of reactive hyperemia index (LnRHI, 0.63 ± 0.2) was correlated with FBG (r = 0.723, P = 0.008). BMI (27.0 ± 3.7 kg/m²) correlated positively with MAP (r = 0.727, P = 0.005).

Conclusion
Our preliminary findings suggest worsening cardiometabolic profiles in prediabetes are linked to impaired cutaneous microvascular function. Reduced nitric oxide bioavailability may underlie these alterations, particularly during thermally induced vasodilation. These associations underscore the importance of early vascular assessment as a potential window for intervention prior to overt CVD.