Hyperosmolar hyperglycemic state (HHNS) is most likely in which patient profile?

• A. Type 1 diabetes with ketosis
• B. Type 2 diabetes with mild dehydration
• C. Type 2 diabetes with severe dehydration and very high blood glucose
• D. Gestational diabetes

Answer: (C)

Hyperosmolar hyperglycemic state occurs when extremely high blood glucose drives marked osmotic diuresis, leading to severe dehydration and increased serum osmolality. It typically happens in people with type 2 diabetes because there is enough insulin to prevent widespread ketone production, so ketosis and acidosis are minimal or absent. The hallmark is very high glucose levels (often well above 600 mg/dL), profound dehydration, and altered mental status, usually in older adults or in those with precipitating factors like infection or dehydration. This is why the most likely profile is someone with type 2 diabetes who is severely dehydrated and has very high blood glucose. In contrast, type 1 diabetes with ketosis points to diabetic ketoacidosis, and gestational diabetes isn’t the classic scenario for HHNS.