16.4 Diabetic Emergencies and Neuroendocrine Disorders

Diabetic emergencies and neuroendocrine water-sodium disorders are osmolar flights, not sugar checks. Domain 4.E.1–2 of the August 2026 Board of Certification for Emergency Nursing (BCEN) Certified Flight Registered Nurse (CFRN) outline tests diabetic ketoacidosis (DKA), hyperosmolar hyperglycemic state (HHS), hypoglycemia, diabetes insipidus (DI), and syndrome of inappropriate antidiuretic hormone secretion (SIADH). Thyroid storm and adrenal crisis were removed from the 2026 outline—do not lecture them; they are outgoing content.

DKA, HHS, and hypoglycemia

Sort the three pictures before you hang insulin.

Three different tanks

DKA is usually a younger type 1 patient (or a failed pump) with anion-gap metabolic acidosis, ketones, Kussmaul breathing, and a glucose that is often in the mid-hundreds to low thousands. Total-body potassium (K+) is depleted even when the first lab looks high. HHS is usually an older type 2 patient with profound dehydration, little or no ketoacidosis, a glucose often above 600 mg/dL, and a very high serum osmolality. Hypoglycemia is the acute brain emergency: confusion, seizure, or coma with a low glucometer. Treat the low glucose immediately with dextrose 50% (D50) intravenous (IV) if you have a line, or glucagon if you do not. Do not fly a seizing stroke whose only number is 38 mg/dL.

Fluids, insulin infusion, potassium, and the pump

Restore circulating volume with isotonic crystalloid first. Typical adult teaching is an initial liter if the patient is shocked, then a slower rate once perfusion returns—those liters are clinical teaching, not BCEN numbers. Check K+ before a meaningful insulin infusion. If potassium is already low (many programs hold insulin below about 3.3 mEq/L), replace K+ first; insulin will drive the rest inside the cell and the heart will stop. Once K+ is safe, start a regular insulin infusion (commonly taught as 0.1 units/kg/hour, sometimes after a small bolus per protocol). Do not catch up with repeated big cabin boluses you cannot titrate.

In HHS, the killer after shock is an overly fast fall in effective osmolality and a swelling brain. Follow glucose and sodium together. When glucose approaches about 200–300 mg/dL, most protocols add dextrose to the fluids so you can keep a low-dose insulin drip without crashing osmolality. Those thresholds are clinical teaching. Young DKA can also swell a brain if osmolality falls too fast—watch mentation, not just the glucometer.

Insulin pump failure is a DKA factory: a disconnected set, an empty reservoir, or a crushed site on a long board. If DKA is in progress, most programs stop the pump and convert to a titratable IV infusion you can actually see. Bring the pump to the receiving team; do not troubleshoot menus in turbulence.

DI and SIADH

These are opposite antidiuretic hormone (ADH) problems.

Diabetes insipidus

DI (central more often in the flight population after head injury, pituitary surgery, or brain-death physiology) is missing ADH: huge urine output (UOP), dilute urine, and a rising sodium. Replace hourly losses and free water carefully so you do not swing sodium the other way. Desmopressin (DDAVP) or a vasopressin infusion is given per protocol—confirm the sending dose, the concentration, and whether this is a diagnostic trial or a maintenance drip. Watch the bag and the Foley every 15–30 minutes. A DI patient can drop a liter of urine while you chart.

SIADH

SIADH is too much ADH: low sodium, inappropriately concentrated urine, and a euvolemic-looking patient. Fluid-restrict. Do not treat dry mucous membranes with hypotonic boluses—that drives sodium lower and can seize the brain. Severe symptomatic hyponatremia (seizure, deep coma) is a hypertonic saline problem per protocol, in small, watched aliquots, not a 30 mL/kg gift. Avoid a rapid over-correction on a long leg; you are flying osmoles, not a single number.

• Sort DKA, HHS, and hypoglycemia before insulin; the low glucose gets dextrose now.
• Fluids first in DKA/HHS; check potassium before the insulin infusion, and replace K+ if it is already low.
• Do not drop HHS osmolality too fast; add dextrose to the fluids when glucose falls into the protocol range.
• Pump failure is DKA until the IV infusion is running; do not manage a pump menu in cruise.
• DI is high UOP and rising sodium (desmopressin/vasopressin per protocol); SIADH is low sodium and concentrated urine (restrict, no hypotonic boluses, hypertonic only if severe).