Type 1 diabetes is an autoimmune disease characterized by T cell-dependent and -mediated chronic inflammatory response that destroys pancreatic insulin-producing beta cells resulting with hyperglycemia and metabolic disturbances. Whereas current treatment strategies rely on insulin, prevention of disease development in susceptible individuals would be the ultimate goal in successful management of T1D. Garcinia kola Heckel (GK) is an African plant known for its wide use in traditional medicine. Its nut is chewed daily as a masticatory believed to exhibit a myriad of beneficial health effects. Some of the therapeutic effects of GK extracts (GKE) have been suggested to be due to their anti-inflammatory potential and influence on the immune system. Despite recent advances in preventative immunotherapy efforts in T1D management, such as manipulating T cells, undesirable side effects still remain a huge challenge. Thus, daily chewing of GK nut, as a T1D preventative measure, seems like an attractive, safe alternative. Previous publications postulated GKE’s anti-inflammatory potential mainly based on antioxidative and radical scavenging properties of GKE, whereas just a few studies, performed in vitro on macrophage cell lines, explicitly explored anti-inflammatory activities. Considering that GKE has never been studied in the context of T1D, and its enormous relevance in folkloric medicine, we aimed to define whether GKE exhibits antidiabetic properties and affects T cells by its anticipated anti-inflammatory action. The effects of GKE treatment has been tested in the experimental murine model(s) of T1D. Our results revealed that long-term daily treatment by 100 mg GKE/ kg in a drinking water, which started in a pre-diabetic phase, did not prevent T1D development, as treated mice did not show either delayed disease onset, less severe glycemia or lower disease frequency. However, while GKE treatment did not exhibit any toxic effects, it did affect T cells and their function. A prominent reduction in frequency of splenic T cells, both the helper (Th) and cytotoxic (Tc) subpopulations of T cells, accompanied by an elevated production of pro-inflammatory cytokines, such as TNF-a, IL-6, and IL-17, and suppressed levels of IL-2, have been found. Overall, our results, while not confirming antidiabetic property of GKE, suggest its potential in pathologies that benefit from potentiated pro-inflammatory Th1-type response. Moreover, this study brings awareness about “cultural myths” on beneficial usage of GKE in diabetes, and emphasizes needs for further in vivo assessment of GK immunomodulatory properties and a thorough scientific elucidation of existing herbal treatments.