Introduction: This study investigated the effect of vitamin D3 injection combined with high-intensity interval training on cell signaling pathways involved in excessive autophagy, specifically the mTOR (mechanistic target of rapamycin)–Beclin-1–Fyco-1 (FYVE and coiled-coil domain-containing protein 1)–cathepsin D pathway, in the heart tissue of Type 2 diabetes–induced rats. Here, CTSD is linked to type 2 diabetes mellitus.