Aim: To compare the levels of gingival crevicular fluid (GCF) interleukin-6 (IL-6) with and without adjunctive injectable platelet-rich fibrin (i-PRF) after scaling and root planing (SRP) in chronic periodontitis patients with type II diabetes. Materials and methods: This was a split-mouth, double-blinded study conducted on 35 chronic periodontitis patients with well-controlled type II diabetes [glycated hemoglobin (HbA1C) value 6.5–7.5%]. The sites were randomly allocated into two groups—group I, i-PRF adjunct to scaling and root planning, and group II, scaling and root planning alone. The clinical attachment level (CAL), probing pocket depth (PPD), gingival bleeding index (GBI), and plaque index (PlI) were recorded at baseline, 1 month, and 3 months. GCF was collected at baseline and 1 month and subjected to enzyme-linked immunosorbent assay (ELISA) for the evaluation of IL-6 levels. Data were statistically analyzed using Jeffreys's Amazing Statistics Program (JASP) version 14. Results: On intergroup comparison, the clinical parameters showed statistically significant results when compared to baseline, 1 month, and 3 months. On intragroup comparison, the mean CAL for group I reduced from 5.09 ± 0.45 to 2.60 ± 0.55, and for group II, it reduced from 5.03 ± 0.57 to 3.63 ± 0.77. The mean PPD for group I reduced from 5.03 ± 0.57 to 2.60 ± 0.55, and for group II, it reduced from 4.94 ± 0.48 to 3.63 ± 0.77. A significant reduction in mean GBI score and PlI score was observed. The mean IL-6 level showed significant improvement within the groups and was not significant when compared between groups I and II. Conclusion: The i-PRF as an adjunct to SRP provided better results when compared with SRP alone in chronic periodontitis patients with type II diabetes. Clinical significance: The i-PRF is an innovative advancement in the field of dentistry. Due to its easy availability and better properties, it can be implemented in various periodontal procedures and in other fields of dentistry.