Omega-3 polyunsaturated fatty acids (PUFAs) represent valuable dietary adjuncts for subjects with hypertriglyceridemia and at increased risk of cardiovascular disease, including subjects with type 1 diabetes (T1D). However, the exact role of omega-3 PUFAs in the regulation of glucose homeostasis and chronic complications in patients with diabetes remains uncertain. Herein, we report a 3-year follow-up of an athlete adolescent with T1D who started to use continuous glucose monitoring (CGM) two years after the diagnosis, and initiated omega-3 PUFA supplementation four years after the clinical onset of T1D. CGM metrics related to a 18-month period of omega-3 PUFA supplementation (50 mg/Kg/day of EPA and DHA) was compared to CGM metrics referring to a 18-month period prior to the nutrition intervention. Omega-3 PUFA supplementation resulted in a significant reduction of mean glucose and glucose variability, along with a significant increase in Time in range (TIR) 70-180 mg/dL. No significant changes were observed in daily insulin requirements between the two study periods. Future studies will be of assistance to better understand the exact impact of omega-3 PUFAs on the regulation of glucose homeostasis in patients with type 1 and its complications.