Stent thrombosis is an infrequent event but a potentially fatal complication of coronary stenting. Adherence to long-term antiplatelet therapy plays an important role in the prevention of late stent thrombosis after drug-eluting stent (DES) implantation. Poor glycemic control due to nonadherence to diabetic treatments is likely to result in severely diffuse coronary atherosclerosis and diabetic microvascular complications. This case report describes fatal very late stent thrombosis in a young diabetic patient, which teaches us about the potential risk of DES in patients with acute myocardial infarction and the importance of patient education about long-term dual antiplatelet therapy after DES implantation. Furthermore, it demonstrates severely diffuse atherosclerosis in a young diabetic patient with nonadherence to diabetic treatments.