Introduction: The aim of this study was to compare the visual outcomes of phacoemulsification with intraocular lens implantation (IOL) surgery in patients with and without diabetes mellitus (DM) in Malaysia over a 12-year period and to identify factors that may contribute to poor visual outcome. Materials and Methods: Data was retrieved from the webbased Malaysian Cataract Surgery Registry (CSR). Perioperative data for cataract surgery performed from 2007- 2018 were analysed. Inclusion criteria were age ≥40 years, phacoemulsification and IOL and senile cataract. Combined surgeries, surgeries performed by trainees and ocular comorbidities were excluded. Post-operative Best-Corrected Visual Acuity (BCVA) were compared. Factors affecting poor visual outcomes among those with DM were analysed using multivariate logistic regression to produce adjusted odds ratio (OR) for variables of interest. Results: Total number of cases between 2007-2018 was 442,858, of whom 179,210 qualified for our analysis. DM group consisted of 72,087 cases (40.2%). There were 94.5% cases in DM group and 95.0% from non-DM group who achieved BCVA ≥6/12 (p<0.001). Among patients with DM, advanced age (70-79 years old, OR: 2.54, 95% Confidence Interva, 95%CI: 1.91, 3.40; 80-89 years old, OR: 5.50, 95%CI: 4.02, 7.51), ≥90 years, OR: 9.77, 95%CI: 4.18, 22.81), poor preoperative presenting visual acuity [<6/18–6/60] (OR: 2.40, 95%CI: 1.84, 3.14) and <6/60-3/60 (OR: 3.00, 95%CI: 2.24, 4.02), <3/60 (OR 3.63, 95%CI: 2.77, 4.74)], presence of intraoperative complication (OR 2.24, 95%CI: 1.86, 2.71) and presence of postoperative complication (OR 5.21, 95%CI: 2.97, 9.16) were significant factors for poor visual outcome. Conclusions: Visual outcomes following phacoemulsification with IOL implantation surgery among cases with DM were poorer compared to cases without DM. Risk factors for poor visual outcomes among cases with DM were identified.