Contents
Overview: Two Hyperglycemic Emergencies
- DKA: absolute insulin deficiency → hyperglycemia + ketosis + acidosis (often type 1)
- HHS: relative insulin deficiency → profound hyperglycemia + dehydration WITHOUT significant ketosis (often type 2)
- Both are precipitated by infection, missed insulin, MI, or new-onset diabetes
- Both are life-threatening fluid/electrolyte emergencies
DKA Pathophysiology
- No insulin → cells starve → fat breakdown produces ketoacids
- Ketones (beta-hydroxybutyrate) cause a high-anion-gap metabolic acidosis
- Hyperglycemia drives osmotic diuresis → dehydration and electrolyte loss
- Kussmaul respirations and fruity (acetone) breath are classic
HHS Pathophysiology
- Enough insulin to suppress ketosis but not hyperglycemia
- Glucose often >600 mg/dL with very high serum osmolality (>320 mOsm/kg)
- Extreme osmotic diuresis → profound dehydration and altered mental status
- Higher mortality than DKA, largely due to severe volume depletion in older patients
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Start Free Practice →DKA vs HHS — Side by Side
- Glucose: DKA usually 250–600; HHS often >600 mg/dL
- Ketones/acidosis: DKA YES (pH <7.3, gap ↑); HHS minimal/none (pH >7.3)
- Osmolality: DKA variable; HHS markedly high (>320)
- Mental status: DKA alert–drowsy; HHS more often obtunded/comatose
- Onset: DKA hours–day; HHS days
Diagnostic Criteria
- DKA: glucose >250, pH <7.3, HCO₃⁻ <18, positive ketones, elevated anion gap
- HHS: glucose >600, osmolality >320, pH >7.3, HCO₃⁻ >18, minimal ketones
- Always look for the trigger (infection is #1)
- Check glucose, ABG/VBG, ketones, electrolytes, and serum osmolality
Step 1 — Fluid Resuscitation (first priority)
- Start isotonic crystalloid (0.9% NaCl) aggressively for volume deficit
- Then switch to 0.45% NaCl once intravascular volume is restored (per corrected Na⁺)
- Add dextrose (D5) when glucose falls to ~200 (DKA) / ~250–300 (HHS) to keep the insulin running
- Fluids alone lower glucose substantially and restore perfusion
Step 2 — Insulin Therapy
- Continuous IV regular insulin infusion (commonly ~0.1 units/kg/hr)
- Do NOT start insulin until K⁺ is known and ≥3.3 mEq/L (insulin drives K⁺ into cells)
- Goal: lower glucose by ~50–75 mg/dL/hr (avoid rapid drops)
- In DKA, continue the drip until the ANION GAP closes — not just until glucose normalizes
Step 3 — Potassium (the high-yield trap)
- Total-body K⁺ is DEPLETED even when serum K⁺ looks normal/high (acidosis shifts K⁺ out of cells)
- Insulin + fluids + correcting acidosis all drive K⁺ back INTO cells → serum K⁺ can crash
- K⁺ <3.3: hold insulin, replace K⁺ first
- K⁺ 3.3–5.2: give insulin AND add K⁺ to fluids; monitor closely
- K⁺ >5.2: insulin/fluids, recheck before adding K⁺
Bicarbonate, Transition & Cerebral Edema
- Bicarbonate is generally NOT given unless pH is very low (e.g., <6.9)
- Overlap subcutaneous insulin 1–2 hours BEFORE stopping the IV drip to avoid rebound
- Cerebral edema: rare but feared, mostly pediatric — from lowering glucose/osmolality too fast
- Watch for headache, declining LOC, or new neuro changes during correction
Nursing Priorities
- Hourly glucose, frequent electrolytes (especially K⁺), and neuro checks
- Strict I&O, cardiac monitoring (K⁺ shifts cause arrhythmias)
- Titrate insulin and dextrose per protocol; never stop the drip abruptly in DKA
- Identify and treat the precipitating cause (cultures, ECG, etc.)
Can you answer these 3 CCRN questions?
Here are 3 questions in the style of our premium bank. The full rationale explains exactly why the right answer is right — and why the distractors trap most test-takers.
Premium Practice Question
A DKA patient has glucose 480, pH 7.12, and serum K⁺ 3.1. What is the priority action?
- Start the insulin infusion immediately
- Hold insulin and replace potassium first
- Give IV bicarbonate
- Bolus 0.45% NaCl
Rationale: Insulin drives potassium intracellularly; with K⁺ below 3.3 it can precipitate life-threatening hypokalemia and arrhythmias, so potassium must be replaced before insulin is started....
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Premium Practice Question
During DKA treatment the glucose has fallen to 200 but the anion gap remains elevated. The nurse anticipates:
- Stopping the insulin drip now
- Adding dextrose and continuing the insulin drip
- Switching to subcutaneous insulin only
- Giving a bolus of bicarbonate
Rationale: In DKA the insulin drip continues until the anion gap closes; when glucose reaches ~200, dextrose is added so insulin can keep clearing ketones without causing hypoglycemia....
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Premium Practice Question
Which findings best distinguish HHS from DKA?
- High ketones and pH 7.10
- Glucose >600, osmolality >320, minimal ketones, pH >7.3
- Kussmaul respirations and fruity breath
- Normal mental status with mild hyperglycemia
Rationale: HHS features extreme hyperglycemia and hyperosmolality with little or no ketosis and a pH above 7.3, whereas DKA is defined by ketoacidosis with a low pH and an elevated anion gap....
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Related CCRN Guides
Frequently Asked Questions
What is the main difference between DKA and HHS?
DKA is caused by an absolute lack of insulin, producing ketones and a high-anion-gap metabolic acidosis with moderately high glucose. HHS is caused by a relative insulin deficiency that suppresses ketosis but allows extreme hyperglycemia (often >600) and severe dehydration with high osmolality and a pH above 7.3.
Why is potassium so important in DKA management?
Total-body potassium is depleted in DKA even when the serum level looks normal or high, because acidosis shifts potassium out of cells. Insulin, fluids, and correcting the acidosis all drive potassium back into cells, so the serum level can fall dangerously. Insulin is held if potassium is below 3.3 until it is replaced.
When is dextrose added during DKA treatment?
Dextrose (D5) is added to the IV fluids when glucose falls to about 200 mg/dL so that the insulin infusion can continue to close the anion gap and clear ketones without causing hypoglycemia.
Should bicarbonate be given in DKA?
Bicarbonate is generally avoided and reserved for severe acidemia (for example, a pH below 6.9), because the acidosis usually corrects with fluids and insulin alone.
What is the priority of treatment in DKA and HHS?
Fluid resuscitation with isotonic saline is the first priority to restore intravascular volume and perfusion, followed by insulin therapy and careful potassium management.
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