This patient is presenting with classic symptoms of hyperglycemic hyperosmolar nonketotic syndrome (HHNS). Her key symptoms include polyuria, polydipsia, and unintentional weight loss which developed acutely over 3 weeks. She now appears lethargic. HHNS is a life-threatening complication of diabetes that develops in patients with type 2 diabetes. Urgent treatment is needed to correct the hyperglycemia and dehydration through IV fluids and insulin therapy. She requires admission to the hospital for close monitoring and management.