DKA at Hour Six: Interpreting Resolution, Not Just Glucose
Mr. T, 28, is admitted with diabetic ketoacidosis. Initial labs: glucose 512 mg/dL, pH 7.12, bicarbonate 10 mEq/L, anion gap 26, K 5.2, BUN 24, creatinine 1.3. He is on 0.9% saline (started at 1 L/hr, now 250 mL/hr), regular insulin infusion at 0.1 units/kg/hr, and hourly point-of-care glucose. Six hours later: glucose 214, pH 7.28, bicarbonate 14, gap 18, K 4.0, HR 96, BP 112/70. He is alert, asking for food, and making adequate urine.
1. Is his therapy on track? What changes do you anticipate, and why?
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Partial success - glucose is falling, but the ketoacidosis has not resolved. Resolution is measured by the anion gap and bicarbonate, not by glucose.
- Add dextrose now. When glucose falls below 200 to 250, add D5 to the IV fluid so the insulin infusion can continue without hypoglycemia. Insulin must keep running to suppress ketogenesis; stopping it because the glucose normalized is the classic cause of rebound ketoacidosis.
- Potassium trajectory 5.2 to 4.0. Insulin drives potassium intracellularly. Recheck and replace to keep it in the 4.0 to 5.0 range with adequate urine output; monitor telemetry.
- Fluids: continue isotonic or switch to 0.45% saline depending on sodium and volume status; avoid over-resuscitation.
- Bicarbonate is not indicated at pH 7.28; it is generally reserved for pH below 6.9.
- Do not stop the drip based on glucose alone; he remains gap-positive.
- Find the precipitant: infection, missed insulin, new medication, pregnancy, substance use.
2. What criteria must be met before transition to subcutaneous insulin, and how do you prevent rebound ketosis?
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Criteria:
- Anion gap 12 or less (some protocols 10 to 12)
- Bicarbonate 15 to 18 or higher and pH greater than 7.3
- Potassium in range, patient hemodynamically stable
- Patient tolerating oral intake and absorbing it
- The precipitating cause is being treated
Preventing rebound:
- Give subcutaneous basal insulin (and prandial coverage) 1 to 2 hours before stopping the infusion. There must be overlap; otherwise there is a window with no insulin on board and ketones rebound within hours.
- Do not transition on the basis of a normal glucose alone - a patient can have a normal glucose and a wide gap.
- Continue hourly glucose checks during the overlap and for several hours after.
- Teach sick-day rules, ketone testing, and never omitting basal insulin.
3. Which complications will you monitor for, and what are the earliest signs?
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- Hypoglycemia: hourly point-of-care glucose during the infusion; earliest signs are diaphoresis, tremor, and confusion. Autonomic neuropathy or beta blockade can mask them, so trend the numbers, not just symptoms.
- Hypokalemia: flat T waves, U waves, ectopy, weakness, ileus. This is the most predictable electrolyte complication of insulin therapy.
- Cerebral edema: headache, declining level of consciousness, bradycardia with rising blood pressure, pupillary change - report immediately. More common in younger patients.
- Fluid overload: crackles, JVD, falling SpO2, especially with cardiac or renal history.
- Hyperchloremic non-gap acidosis: gap has closed but bicarbonate and pH remain low after large saline volumes; recognize it so it is not mistaken for unresolved ketoacidosis.
- VTE and aspiration risk from dehydration and gastric stasis.
Evaluation is a comparison: gap, bicarbonate, pH, potassium, mentation, and hemodynamics at each interval - not a single glucose value.