Background: Acute necrotizing esophagitis (ANE), also known as “black esophagus,” is a rare but life-threatening condition typically occurring in critically ill patients with profound systemic disturbances. Extreme hyperglycemic crises represent an underrecognized precipitating factor, capable of inducing severe metabolic, inflammatory, and microvascular injury. Case Presentation: We report the case of a 54-year-old male admitted with altered mental status and severe dehydration, in whom initial laboratory evaluation revealed extreme hyperglycemia (serum glucose ~1000 mg/dL), metabolic acidosis, and early multiorgan dysfunction. During intensive care unit hospitalization, the patient developed anemia and severe thrombocytopenia, followed by evidence of upper gastrointestinal bleeding. Urgent upper gastrointestinal endoscopy demonstrated diffuse circumferential black necrosis of the distal esophageal mucosa with abrupt demarcation at the gastroesophageal junction, consistent with acute necrotizing esophagitis, along with associated erosive hemorrhagic gastritis. Comprehensive laboratory evaluation documented marked inflammatory activation and hematologic instability. Management and Outcome: Treatment consisted of aggressive metabolic correction, strict glycemic control, hemodynamic stabilization, infection management, and supportive gastrointestinal care. Progressive clinical and biological improvement was observed, with resolution of bleeding and partial recovery of hematologic parameters. Conclusions: This case highlights a severe hyperglycemic crisis as a major contributing factor within a multifactorial ischemic and inflammatory cascade leading to acute necrotizing esophagitis.