Peri-implantitis is an inflammatory condition affecting the soft and hard tissues surrounding dental implants, often leading to implant failure. This retrospective study aims to evaluate the relationship between systemic diseases and the duration of onset of peri-implantitis. Understanding this relationship may help in the early identification and management of at-risk patients. Materials and Methods A retrospective review of 200 patient records who received dental implants between 2015 and 2020 was conducted. Patients were grouped based on the presence or absence of systemic diseases such as diabetes mellitus, cardiovascular diseases, and autoimmune disorders. The duration of onset of peri-implantitis was recorded from the date of implant placement to the first clinical diagnosis of peri-implantitis. Statistical analysis was performed to evaluate the correlation between systemic diseases and the duration of onset of peri-implantitis. Results Out of 200 patients, 60% (n=120) had one or more systemic diseases. The average duration of onset of peri-implantitis in patients with systemic diseases was 18 months (SD ± 5 months), while in patients without systemic diseases, it was 30 months (SD ± 7 months). A statistically significant difference (p < 0.05) was found between the two groups, indicating a faster onset of peri-implantitis in patients with systemic diseases. Conclusion The findings of this retrospective study suggest a significant relationship between systemic diseases and the accelerated onset of peri-implantitis. Patients with systemic conditions such as diabetes, cardiovascular diseases, and autoimmune disorders are at a higher risk for early development of peri-implantitis. These insights underscore the importance of meticulous monitoring and preventive strategies for at-risk patients to enhance implant longevity and success.