Thymoquinone (TQ), a bioactive compound derived from black cumin seeds, is renowned for its potent anti-obesity and anti-diabetic properties. Due to the stability challenges of TQ, it has predominantly been utilized in oil formulations. This study aimed to enhance the stability of TQ and investigated the impact of consuming insoluble fiber from black cumin seeds on restoring antioxidant function compromised by diabetes and improving hyperglycemia management. We evaluated the restorative effects of a 35-day administration of black cumin seed extract (BCS) on antioxidant function impaired by streptozotocin (STZ)-induced diabetes, alongside structural and functional alterations in the pancreas, liver, and kidneys. The results demonstrated significant improvements in organ weight, particularly in pancreatic tissue. Moreover, BCS administration markedly suppressed the expression of key genes associated with pancreatic dysfunction and damage, including caspase-3, transforming growth factor-beta 1 (TGF-β1), and interleukin-1 beta (IL-1β). Through oral glucose tolerance tests (OGTTs), BCS was found to effectively regulate chronic hyperglycemia and exhibit potential for managing acute hyperglycemia. These findings suggest that BCS not only addresses both glycemic and non-glycemic complications of diabetes but also offers a safe, long-term solution. Consequently, BCS emerges as a promising therapeutic agent for hyperglycemia management, including in prediabetic stages.