In an adult with a random plasma glucose of 452 mg/dL, what immediate therapy should be administered?

Immediate Management of Severe Hyperglycemia (Random Blood Glucose 452 mg/dL)

Administer rapid-acting insulin immediately—either 10 units intravenously or 10–15 units subcutaneously—to bring this dangerously elevated glucose down within 1–2 hours, while simultaneously checking for ketones and initiating aggressive fluid resuscitation with 0.9% normal saline. 1

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Immediate Assessment & Triage

Check for Diabetic Ketoacidosis (DKA) or Hyperosmolar Hyperglycemic State (HHS)

• Measure urine or blood ketones immediately in any patient with glucose >300 mg/dL, especially if accompanied by nausea, vomiting, abdominal pain, or altered mental status. 1, 2
• Obtain serum electrolytes urgently when glucose exceeds 300 mg/dL to assess for hyperosmolar state, which requires ICU-level care. 2, 3
• If ketonuria is present or ketonemia ≥0.5 mmol/L, treat as early DKA and summon a physician promptly. 1

Determine Diabetes Type & Current Regimen

• Type 1 diabetes or insulin-dependent type 2 diabetes: Requires immediate insulin therapy to prevent ketoacidosis. 1
• Type 2 diabetes not on insulin: May still require urgent insulin initiation given the severity of hyperglycemia. 1
• Current medications: Identify if the patient is on any insulin, oral agents, or GLP-1 receptor agonists. 1

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Immediate Insulin Therapy

Intravenous Insulin (Preferred for Severe Hyperglycemia with Symptoms)

• Start continuous IV insulin infusion at 0.1 units/kg/hour (approximately 6–10 units/hour for most adults) if the patient has signs of DKA, HHS, or is critically ill. 1, 4
• Alternative bolus approach: Give 10 units of regular insulin IV push, then start infusion at 0.05–0.1 units/kg/hour. 4, 5
• Monitor capillary glucose every 1–2 hours during IV insulin therapy to guide dose adjustments. 2, 3, 4
• Target glucose reduction: Aim for 50–75 mg/dL decrease per hour initially, then maintain glucose 140–180 mg/dL. 1, 4

Subcutaneous Insulin (If Patient is Stable & Not Critically Ill)

• Give 10–15 units of rapid-acting insulin (lispro, aspart, or glulisine) subcutaneously immediately for glucose 452 mg/dL. 1, 6
• Alternative: Administer 10 units of regular insulin subcutaneously, though absorption is slower than rapid-acting analogs. 7, 6
• Recheck glucose in 1–2 hours; if glucose remains >300 mg/dL, give an additional 5–10 units of rapid-acting insulin. 1

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Concurrent Fluid Resuscitation

Aggressive IV Hydration

• Start 0.9% normal saline at 500–1000 mL/hour for the first 1–2 hours to correct dehydration and improve insulin sensitivity. 1, 2, 3
• Adjust rate based on hemodynamic status: Continue at 250–500 mL/hour after initial bolus. 2, 3
• Switch to 0.45% saline if serum sodium is elevated or normal after initial resuscitation. 1

Dextrose Addition (When Glucose Falls Below 250 mg/dL)

• Add dextrose 5% to IV fluids once glucose drops to 200–250 mg/dL to prevent hypoglycemia while continuing insulin therapy. 1, 2

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Transition to Scheduled Insulin Regimen

From IV to Subcutaneous Insulin

• Calculate total 24-hour IV insulin dose once glucose is stable at ≤180 mg/dL. 1, 2
• Give 50% as basal insulin (glargine or detemir) once daily and 50% as prandial insulin (lispro, aspart, or glulisine) divided among three meals. 1, 2
• Administer first subcutaneous basal dose 2–4 hours before stopping IV insulin to prevent rebound hyperglycemia. 1, 2

Initiating Basal-Bolus Therapy (If Not Previously on Insulin)

• Start with total daily dose of 0.3–0.5 units/kg/day for severe hyperglycemia (glucose ≥300 mg/dL or HbA1c ≥9%). 1
• Example for 70 kg patient: Total 21–35 units/day → 11–18 units basal (once daily) + 11–18 units prandial (divided among three meals). 1
• Titrate basal insulin by 4 units every 3 days if fasting glucose remains ≥180 mg/dL. 1

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Monitoring & Safety

Glucose Monitoring Frequency

• Every 1–2 hours during IV insulin therapy or acute hyperglycemia management. 2, 3, 4
• Before each meal and at bedtime (minimum 4 times daily) once transitioned to subcutaneous insulin. 1
• Every 4–6 hours if patient is NPO or has poor oral intake. 1

Hypoglycemia Prevention

• Treat glucose <70 mg/dL immediately with 15 g fast-acting carbohydrate (oral) or IV dextrose if unconscious. 1, 2
• Give 10–15 g dextrose IV bolus (100–150 mL of 10% dextrose or 20–30 mL of 50% dextrose) for unconscious patients. 2
• Reduce insulin dose by 10–20% if unexplained hypoglycemia occurs. 1

Electrolyte Monitoring

• Check serum potassium every 2–4 hours during insulin therapy, as insulin drives potassium intracellularly. 1
• Replete potassium if <3.3 mEq/L before starting insulin to prevent life-threatening hypokalemia. 1

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Common Pitfalls to Avoid

• Never delay insulin administration when glucose is >400 mg/dL; prolonged severe hyperglycemia increases risk of DKA, HHS, and complications. 1
• Do not rely solely on correction (sliding-scale) insulin without scheduled basal insulin; this reactive approach is condemned by major diabetes guidelines. 1
• Never abruptly stop IV insulin without overlapping subcutaneous basal insulin, as this causes dangerous rebound hyperglycemia and potential ketoacidosis. 1, 2
• Avoid giving rapid-acting insulin at bedtime as a sole correction dose, as this markedly raises nocturnal hypoglycemia risk. 1
• Do not ignore altered mental status—check glucose immediately and consider hyperosmolar state, especially in type 2 diabetes. 2, 3

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Expected Clinical Outcomes

• With IV insulin infusion: Glucose should decrease by 50–75 mg/dL per hour initially, reaching 140–180 mg/dL within 4–6 hours. 1, 4
• With subcutaneous insulin: Glucose should decrease by 50–100 mg/dL within 2–4 hours, though response is more variable. 6
• Properly implemented basal-bolus therapy: Approximately 68% of patients achieve mean glucose <140 mg/dL versus 38% with sliding-scale insulin alone. 1