Diabetic Ketoacidosis — Adult

Key Points

• Confirm ketosis and metabolic acidosis; do not rely on hyperglycemia alone because euglycemic DKA occurs.
• Measure beta-hydroxybutyrate directly when available and use venous blood gas for acid-base assessment.
• Check potassium before insulin and correct significant hypokalemia first.
• Fluid therapy restores circulation but should be individualized in heart failure, kidney disease, pregnancy, and older adults.
• Add dextrose before glucose reaches normal so insulin can continue until ketonemia clears.
• Do not use bicarbonate routinely; reserve it for extreme acidemia under a defined protocol.
• Search for the precipitating cause, especially missed insulin, infection, ischemia, pancreatitis, medication effects, and SGLT2 inhibitor use.
• Overlap IV insulin with long-acting subcutaneous insulin during transition to prevent recurrence.

Algorithm

1. Assess airway, circulation, mental status, volume depletion, and the precipitating illness; obtain ECG and IV access.
2. Measure glucose, electrolytes, creatinine, venous pH, bicarbonate, beta-hydroxybutyrate, magnesium, and targeted precipitant studies.
3. Start isotonic crystalloid and reassess hemodynamics, urine output, sodium, and osmolality.
4. If potassium is too low for safe insulin therapy, replace potassium and hold insulin temporarily.
5. Start insulin once potassium is safe; monitor glucose hourly and electrolytes and acid-base status every 2 to 4 hours during active treatment.
6. Add dextrose-containing fluid as glucose falls while continuing insulin to suppress ketogenesis.
7. Replace potassium according to serial levels; replace phosphate only for a clear indication.
8. When ketoacidosis has resolved and oral intake is possible, transition to subcutaneous insulin with appropriate overlap and address the trigger before discharge.

Clinical Synopsis & Reasoning

DKA results from absolute or relative insulin deficiency with excess counter-regulatory hormones, producing lipolysis, ketone generation, osmotic diuresis, dehydration, electrolyte loss, and metabolic acidosis. Patients may present with polyuria, polydipsia, weight loss, nausea, vomiting, abdominal pain, tachypnea, Kussmaul respirations, dehydration, or altered mental status. Infection, missed insulin, new-onset diabetes, myocardial infarction, stroke, pancreatitis, pregnancy, glucocorticoids, sympathomimetics, and SGLT2 inhibitors are important precipitants. The modern diagnostic approach emphasizes direct measurement of beta-hydroxybutyrate rather than relying only on the anion gap or urine ketones. DKA can occur with only modest glucose elevation, particularly during pregnancy, prolonged fasting, or SGLT2 inhibitor exposure. Initial studies should include glucose, electrolytes, creatinine, venous blood gas, beta-hydroxybutyrate, magnesium, phosphate when clinically relevant, urinalysis, ECG, and investigations for the precipitating illness. Corrected sodium or effective osmolality helps interpret water deficit and overlap with hyperosmolar hyperglycemic state. Serum potassium is often normal or high at presentation despite a large total-body potassium deficit, so treatment can rapidly unmask hypokalemia. Cerebral edema is uncommon in adults but neurologic deterioration during treatment requires immediate evaluation. DKA and HHS exist on a spectrum and mixed presentations are common, especially in older adults with type 2 diabetes.

Treatment Strategy & Disposition

Begin with isotonic crystalloid, using balanced crystalloid or saline according to availability and patient factors. Restore perfusion promptly but avoid indiscriminate fluid loading in older adults or those with heart or kidney failure. Check potassium before insulin whenever possible. If potassium is markedly low, replace potassium first and delay insulin until it has risen to a safe level because insulin will shift potassium intracellularly. Once potassium permits, use IV regular insulin for severe or complicated DKA; selected mild to moderate uncomplicated cases can be managed with protocolized subcutaneous rapid-acting insulin in appropriate monitored settings. Add dextrose-containing fluid as glucose falls so insulin can continue until ketonemia and acidosis resolve. Potassium replacement is usually required even when the initial concentration is normal. Routine bicarbonate is not indicated and is generally reserved for extreme acidemia. Routine phosphate replacement is also unnecessary unless there is severe hypophosphatemia with clinically important muscle, respiratory, or cardiac dysfunction. Identify and treat the precipitating cause without reflexively prescribing antibiotics when infection is not supported. Resolution requires improvement of ketoacidosis, ideally using beta-hydroxybutyrate and acid-base criteria, rather than closure of an anion gap alone. Transition to subcutaneous basal-bolus insulin with an overlap period to prevent rebound ketosis. ICU care is appropriate for severe acidosis, shock, significant altered mental status, major electrolyte instability, or another critical precipitating illness.

Epidemiology / Risk Factors

• DKA occurs in type 1 diabetes and in insulin-deficient type 2 diabetes, including ketosis-prone diabetes.
• Missed or inadequate insulin and acute infection are among the most common precipitants.
• SGLT2 inhibitors increase the risk of euglycemic DKA, particularly with fasting, surgery, acute illness, or low carbohydrate intake.
• Pregnancy lowers the glucose threshold at which DKA can occur and requires early obstetric involvement.
• Recurrent DKA often reflects barriers to insulin access, diabetes education, mental health, substance use, or social instability rather than a purely biomedical failure.

Investigations

DKA Severity (Adult)

Pharmacology

Prognosis / Complications

• Mortality from uncomplicated DKA is low with timely protocolized care but rises with advanced age, shock, severe comorbidity, and mixed DKA-HHS.
• Hypokalemia, hypoglycemia, fluid overload, and treatment-related hyperchloremic acidosis are preventable complications of therapy.
• Recurrent DKA predicts future hospitalization and should trigger a focused prevention plan.
• Neurologic deterioration during treatment is uncommon in adults and requires urgent evaluation for cerebral edema, stroke, severe osmolality shifts, or another cause.
• Successful discharge depends on reliable access to insulin, glucose or continuous glucose monitoring supplies, and follow-up.

Patient Education / Counseling

• Review sick-day rules, including never stopping basal insulin solely because oral intake is poor unless a clinician has provided a specific alternative plan.
• Teach ketone testing during illness, persistent hyperglycemia, nausea, vomiting, or SGLT2 inhibitor use when advised.
• Advise urgent care for persistent vomiting, moderate or high ketones, deep rapid breathing, confusion, or inability to keep fluids down.
• If taking an SGLT2 inhibitor, review perioperative and acute-illness hold instructions and the possibility of DKA with near-normal glucose.
• Confirm the patient has insulin, needles or pump supplies, glucose monitoring, a rescue contact plan, and timely diabetes follow-up before discharge.

Electrolyte Notes

Potassium management is central to safe DKA treatment. Total-body potassium is depleted by osmotic diuresis even when extracellular potassium is elevated from acidosis and insulin deficiency. Once insulin and fluids are started, potassium can fall quickly. Serial potassium measurement therefore determines whether insulin can begin, how much potassium should be added to IV fluids, and whether telemetry is needed. Magnesium deficiency can make hypokalemia harder to correct. Phosphate also falls with insulin but routine replacement has not improved outcomes and can provoke hypocalcemia, so it should be reserved for severe depletion or clinically important muscle, respiratory, or cardiac dysfunction. During recovery, a normalizing glucose does not mean DKA has resolved. Continue insulin with added dextrose until ketonemia and acidosis have cleared and a safe subcutaneous insulin plan is established.

References

1. Hyperglycemic Crises in Adults With Diabetes: A Consensus Report — Link