Background <p>Plantar pressure distribution is a key marker of lower limb neuromuscular function and gait stability in patients with cervical spondylotic myelopathy (CSM). Diabetes mellitus (DM) impairs neurological recovery, but its impact on postoperative plantar pressure improvement in CSM remains unclear. This study explored the association between preoperative glycated hemoglobin (HbA1c) and long-term plantar pressure changes after anterior cervical surgery in CSM patients with DM.</p> Methods <p>We retrospectively analyzed 71 CSM patients with DM who underwent anterior cervical discectomy and fusion (ACDF) between 2018 and 2022, with 2-year follow-up. Primary outcomes included 2-year changes in medial (ΔMFP2) and lateral foot pressure (ΔLFP2). Correlations between preoperative HbA1c and plantar pressure improvement were analyzed using linear regression. Binary logistic regression identified risk factors for poor recovery, and ROC analysis determined the optimal HbA1c threshold.</p> Results <p>Preoperative HbA1c was an independent predictor of ΔMFP2 (<i>P</i> = 0.012) and ΔLFP2 (<i>P</i> = 0.026) at 2 years, with higher HbA1c associated with smaller improvements. No significant correlation was observed between HbA1c and 6-month plantar pressure changes (<i>P</i> &gt; 0.05). ROC analysis identified preoperative HbA1c ≤ 6.8% as optimal for favorable ΔMFP2 (AUC = 0.72, sensitivity = 71.4%, specificity = 75.0%) and ≤ 6.7% for ΔLFP2 (AUC = 0.68, sensitivity = 68.2%, specificity = 70.3%). Plantar pressure improvement strongly correlated with 2-year JOA score recovery (<i>r</i> = 0.68 and 0.71, <i>P</i> &lt; 0.001).</p> Conclusions <p>Preoperative HbA1c levels predict long-term plantar pressure improvement after ACDF in CSM patients with DM. Maintaining HbA1c ≤ 6.7% may optimize medial/lateral foot pressure recovery, supporting stringent perioperative glycemic control.</p>