Chloroquine (CQ) and hydroxychloroquine, are promising anti-inflammatory drugs for the treatment of Diabetes mellitus (DM) to prevent associated complications. Therefore, this study evaluated the anti-inflammatory effects of CQ-free and CQ-incorporated polylactic acid nanoparticles (NPs) in the peripheral blood mononuclear cells (PBMCs) of patients with type 1 Diabetes mellitus (T1DM). In total, 25 normoglycemic individuals and 25 patients with T1DM aged 10-16 years were selected and glycemic controls evaluated. After cell viability assessed by MTT assay, T1DM PBMCs were subjected to a CQ concentration of 10 µM in three different conditions: not treated (NT), treated with CQ, and treated with CQ NPs. The cells were incubated for 48 h, and the mRNA expressions of cytokines IL1B, IFNG, TNFA, IL12, and IL10 were determined by relative quantification through real-time PCR at 24 h intervals. IL1B expression decreased in CQ and CQ NP-treated cells after 48 h (p < 0.001) and 24 h (p < 0.05) of treatment, respectively. IFNG and IL12 expressions significantly decreased (p < 0.001) in cells treated with CQ and CQ NPs at 24 and 48 h compared to NT. TNFA and IL10 expressions significantly decreased after 48 h (p < 0.001) and 24 h (p < 0.002), respectively, by both CQ and CQ NPs treatment. Despite being a preliminary in vitro study, CQ has anti-inflammatory activity in the primary cells of T1DM patients and could represent an alternative and adjuvant anti-inflammatory therapy to prevent diabetes complications.