How is hyperosmolar hyperglycemic state (HHS) distinguished from DKA clinically and biochemically?

• A. Glucose typically >600 mg/dL; severe dehydration; hyperosmolarity; minimal ketosis; little acidosis.
• B. Low glucose with severe acidosis.
• C. High insulin levels with ketosis.
• D. Ketosis is prominent with high ketone bodies.

Answer: (A)

Hyperosmolar hyperglycemic state is defined by an extremely high blood glucose level with severe dehydration from osmotic diuresis, and a hyperosmolar serum environment, while ketosis and acidosis are minimal. The very high glucose drives large volumes of water loss, concentrating the serum and elevating osmolality, which often leads to marked mental status changes. Because there is still some insulin around, ketone production is limited, so there is little to no acidosis. This combination—glucose typically very high (often >600 mg/dL), profound dehydration, hyperosmolarity, and minimal ketosis with little acidosis—best fits the pattern of HHS.

In contrast, DKA centers on significant insulin deficiency that triggers rapid lipolysis and ketone production, producing a high anion gap metabolic acidosis with elevated ketones. Glucose can be elevated but is usually not as extreme as in HHS, and dehydration is present but not as severe. The presence of marked ketosis and acidosis is the hallmark that differentiates DKA from HHS.