Euglycemic Hyperosmolar Hypernatremic State: A Variant Subtype of Traditional Hyperosmolar Hyperglycemic State With Higher Mortality.

Background: Hyperosmolar hyperglycemic state (HHS) is a serious and potentially life-threatening complication of diabetes, defined by serum glucose >600 mg/dL and effective osmolality >320 mOsm/kg. However, some patients present with hyperglycemia (serum glucose levels ≥180 mg/dL but <600 mg/dL), hypernatremia, and effective osmolality >320 mOsm/kg. We refer to this subtype of HHS as euglycemic hyperosmolar hypernatremic state.

Objective: We aimed to investigate its clinical characteristics compared to traditional HHS.

Methods: A retrospective observational study of consecutive adult patients with diabetes and effective osmolality >320 mOsm/kg admitted between January 2021 and February 2023 in a single medical institution. The study analyzed age, sex, hemoglobin A1c (HbA1c), serum glucose, serum sodium, effective osmolality, and mortality of encounters of euglycemic hyperosmolar hypernatremic state and traditional HHS.

Results: We encountered 34 cases of euglycemic hyperosmolar hypernatremic state and 19 cases of traditional HHS. Patients with euglycemic hyperosmolar hypernatremic state were older, had less severe diabetes with lower baseline HbA1c, worse hypernatremia, lower effective osmolality, and higher mortality (35.3 % vs. 0 %; p = 0.002) compared to patients with traditional HHS. Euglycemic hyperosmolar hypernatremic state had a similarly high mortality rate as hypernatremia alone.

Conclusions: Euglycemic hyperosmolar hypernatremic state is a variant subtype of HHS. It shares the same pathophysiological mechanisms as traditional HHS but is associated with higher mortality, thus warranting increased recognition as it requires similar treatment strategy as traditional HHS.