Background <p>Cardiovascular and thromboembolic complications remain a major burden in diabetes. We aimed to determine whether peripheral thermometry is suited to detect plantar temperature downshifts (PTDs). Plantar infrared images (PIRIs) and sensor recordings were correlated with atrial fibrillation (AF) and thromboembolic events in patients with diabetes.</p> Methods <p>A secondary analysis of the SmartPreventDiabeticFeet study including 239 patients monitored by PIRIs and sensor-equipped insoles (median follow-up 67.1 months) was conducted. In a structured telephone survey, histories of AF and thromboembolic events (stroke, pulmonary embolism [PE], peripheral arterial disease [PAD]) were captured from enrollment to post-intervention period. Patients with &gt;30 days of temperature recordings (<i>n</i> = 118) were classified according to pre-specified PTD definitions, unsupervised clustering of bilateral plantar temperature variability, and plantar infrared image symmetry. Associations were tested using χ² or Fisher’s exact tests and multivariable logistic/Cox models.</p> <b>Results</b> <p>Our findings show that PTDs in sensor recordings as well as PIRI asymmetry are associated with a higher incidence of a composite of AF and thromboembolic events. Overall, 45 patients experience AF (<i>n</i> = 26), stroke (<i>n</i> = 6), PE (<i>n</i> = 4) or PAD (<i>n</i> = 11). Event rates are higher in patients with PTDs (25.8% vs 11.5%; <i>p</i> = 0.09; exploratory trend). For the elevated temperature variability cluster, the adjusted OR reaches 13.5 [95% CI 3.8–58.6] (34.0% vs 9.9%; <i>p</i> = 0.003; adjusted HR 13.3 [95% CI 1.5–120.4]). In individuals with plantar infrared image asymmetry, the likelihood is 48.6% compared to 6.2% in the symmetry group (<i>p</i> &lt; 0.0001).</p> <b>Conclusions</b> <p>In patients with diabetes, plantar temperature downshifts are associated with thromboembolic risk constellation.</p> <p></p>