Atypical Presentation of New Onset Diabetes with Hyperglycemic Hyperosmolar State in Two Toddlers.

Hyperglycemic hyperosmolar state (HHS), or mixed HHS with diabetic ketoacidosis (DKA), is a rare complication of diabetes in children. Prompt recognition of hyperosmolality is necessary to prevent morbidity and mortality. We report two of the youngest cases with HHS, both presenting at new onset of type 1 diabetes. The first was a 3-year-4-month-old male with autism spectrum disorder who presented with glucose 76.0 mmol/L (1370 mg/dl), calculated serum osmolality 388 mOsm/kg, and trace urinary ketones, consistent with HHS and complicated by acute kidney injury. The second was a 4-year-7-month-old male with Trisomy 21 and autism spectrum disorder who presented with glucose 117.3 mmol/L (2114 mg/dL), calculated serum osmolality 401 mOsm/kg, and elevated serum β-hydroxybutyrate, consistent with mixed HHS-DKA and complicated by acute kidney injury and pancreatitis. Both received aggressive rehydration although hyperosmolality was initially overlooked, resulting in earlier and higher insulin dosing more typical of DKA than HHS. Both recovered without sequelae. In each case, young age and developmental delay likely contributed to hyperosmolality, given the inability to communicate increased thirst and freely access water. A high index of suspicion for HHS is necessary as significant rehydration and delayed start of low dose insulin infusion are recommended to prevent complications.