🫀 Physiological Adaptation · Lesson 4 of 10 · 7 min

DKA Versus HHS: Ketones, Fluids and the Potassium Trap

🍎 A type 1 diabetic with fruity breath and a glucose of 480. A type 2 diabetic with a glucose of 900 and no ketones at all. Same disease family, different emergencies, and one shared trap that kills: potassium.

💡 Key idea

DKA has ketones and Kussmaul breathing; HHS has higher glucose and no ketones. Fluids first, then insulin, add dextrose once glucose is below 250, and watch potassium fall.

🧠 Why it matters

DIABETIC KETOACIDOSIS, usually in type 1: glucose of 200 or more (classically above 250), KETONES in blood and urine, a pH below 7.30, deep rapid Kussmaul respirations, FRUITY breath, nausea, abdominal pain and dehydration; triggered by infection, missed insulin or new onset. HYPERGLYCEMIC HYPEROSMOLAR STATE, usually in type 2 and older adults: glucose above 600, NO significant ketones, extreme dehydration, altered mental status and seizures; slower onset, higher mortality. Treatment for both: isotonic IV FLUIDS first, then an IV REGULAR INSULIN infusion to lower glucose by about 50 to 75 mg/dL per hour, adding dextrose to the IV fluids once glucose falls below 250 to avoid hypoglycemia and cerebral edema. THE POTASSIUM TRAP: the initial potassium may look normal or high, but insulin drives potassium into cells and the level crashes; monitor potassium every hour or two, replace it as ordered, and HOLD insulin if the potassium is below 3.5 (older protocols say 3.3) until it is replaced. Monitor glucose hourly, the cardiac rhythm, and mental status. Sick-day teaching: never skip insulin when ill, check glucose and ketones every 4 hours, drink fluids, and call for persistent vomiting or ketones.

🏥 In the real world

⚠️ A DKA client's potassium is 5.4 on arrival. Three hours into the insulin drip it is 3.1 and the monitor shows U waves. The nurse holds the insulin, hangs the potassium replacement and notifies the provider. The high admission potassium hid a total-body deficit, because acidosis and the lack of insulin had shifted potassium out of the cells. The exam builds this question because real units have built it too.

📌 Takeaways

DKA: ketones, acidosis, Kussmaul, fruity breath; HHS: glucose over 600, no ketones
Fluids, then insulin; add dextrose once glucose is below 250
Potassium falls with insulin: check often, replace, hold insulin below 3.5

📖 Terms in this lesson

Diabetic ketoacidosis (DKA): High glucose with ketones and acidosis, usually in type 1 diabetes, treated with fluids, IV regular insulin and potassium.

Hyperglycemic hyperosmolar state (HHS): Extreme hyperglycemia without significant ketones, usually in type 2 diabetes, with severe dehydration and altered mental status.

Blood glucose critical values: Below 70 mg/dL is hypoglycemia (treat with 15 grams of carbohydrate if awake, IV dextrose or glucagon if not); below 40 or above about 500 is a critical value, and HHS runs above 600.

Urine ketones: Normally negative; moderate or large ketones with a high glucose mean the body is burning fat for fuel, as in diabetic ketoacidosis, so sick-day teaching checks them every 4 hours and reports persistent ketones or vomiting.

Regular insulin: The standard IV insulin, so it runs the DKA infusion with hourly glucose and potassium checks (potassium falls as insulin pushes it into cells); when mixed with NPH, the clear regular is drawn up before the cloudy NPH.

✅ Test yourself

A client with DKA on an insulin infusion has a potassium level of 3.0 mEq/L. What should the nurse do?

Give oral potassium only
Continue the insulin and recheck in 4 hours
Increase the insulin rate
Hold the insulin and replace potassium

Answer: D · Hold the insulin and replace potassium

Insulin drives potassium into cells; with a level below 3.5 (3.3 in older protocols), insulin is held until potassium is replaced to prevent fatal arrhythmias.

Which finding distinguishes diabetic ketoacidosis from hyperglycemic hyperosmolar state?

Hyperglycemia
Dehydration
Ketones and acidosis
Altered mental status

Answer: C · Ketones and acidosis

Both have hyperglycemia and dehydration; ketone production and metabolic acidosis are the hallmarks of DKA.

A client's glucose falls to 220 mg/dL during treatment for DKA. Which change does the nurse anticipate?

Doubling the insulin rate to clear ketones faster
Giving an oral hypoglycemic agent
Stopping all IV fluids and the insulin infusion
Adding dextrose to the IV fluids

Answer: D · Adding dextrose to the IV fluids

Adding dextrose prevents hypoglycemia and lets insulin continue to clear ketones; stopping insulin abruptly would worsen the acidosis.

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