Which patient population is most commonly affected by hyperosmolar hyperglycemic state (HHNS)?

• A. Older adults with type 2 diabetes, profound dehydration, hyperglycemia, high osmolality, minimal ketosis
• B. Young children with DKA
• C. Pregnant women
• D. Type 1 diabetics with ketoacidosis

Answer: (A)

HHNS is a disease pattern that shows up most often in older adults with type 2 diabetes. In this scenario the body has enough insulin to keep lipolysis and ketone production minimal, so there isn’t the same level of ketoacidosis you see in diabetic ketoacidosis. Yet there’s enough hyperglycemia to drive massive water loss through osmotic diuresis, leading to profound dehydration and a very high serum osmolality. That combination—older age, type 2 diabetes, severe hyperglycemia with high osmolality, and little ketosis—defines HHNS.

This differs from diabetic ketoacidosis, which tends to occur in younger patients with type 1 diabetes and presents with significant ketosis and metabolic acidosis. Pregnancy can involve hyperglycemia too, but HHNS isn’t the typical pattern there, whereas DKA can occur in pregnant patients.