• Patient with history of type 2 diabetes who has not been using medications presents with nausea/vomiting and confusion found to have a glucose level of 890 and a serum osmolality of 316, most consistent with Hyperosmolar hyperglycemic state
• Key idea: Serum osmolality = (Na x 2) + (Glucose/18) + (BUN/2.6) + (Ethanol/4.6)
• Key idea: The hyponatremia is secondary to the hyperosmolar state, and therefore is not the primary cause of confusion in this patient

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R/O hyponatremia by corrected sodium = serum sodium + 1.6*(glucose-100)/100