What is the starting dose for an insulin (regular insulin) infusion?

Insulin Infusion Starting Dose

For diabetic ketoacidosis (DKA) or hyperglycemic hyperosmolar state (HHS), start regular insulin at 0.1 units/kg/hour continuous IV infusion (approximately 7 units/hour for a 70 kg patient) without an initial bolus, or alternatively give a 0.15 units/kg bolus followed by 0.1 units/kg/hour infusion. 1

Critical Pre-Infusion Requirements

• Never initiate insulin if serum potassium is <3.3 mEq/L – insulin drives potassium intracellularly and can precipitate life-threatening cardiac arrhythmias 1
• Correct severe hypokalemia first before starting any insulin therapy 1
• Check electrolytes every 2-4 hours during active DKA/HHS treatment 1

DKA/HHS Protocol

Standard dosing:

• Start at 0.1 units/kg/hour continuous IV infusion of regular insulin 1
• For a 70 kg patient, this equals approximately 7 units/hour 1
• Alternative approach: give 0.15 units/kg bolus followed by 0.1 units/kg/hour infusion 1

Expected response and adjustments:

• Target glucose decline is 50-75 mg/dL per hour 1
• If inadequate response, verify hydration status and double the infusion rate hourly until achieving steady decline 1
• When glucose reaches 200 mg/dL (DKA) or 250 mg/dL (HHS), decrease infusion rate to 0.05 units/kg/hour and add dextrose-containing fluids 1

Recent research supports that a priming bolus is unnecessary if an adequate continuous infusion rate of 0.14 units/kg/hour (approximately 10 units/hour in a 70 kg patient) is used, though this higher rate is not standard guideline practice 2. The FDA label for Humulin R describes an initial dose of 0.5 units/hour for IV administration in type 1 diabetes, adjusted to maintain near-normoglycemia 3, but this is for non-emergent hyperglycemia management, not DKA.

General Hyperglycemia Management (Non-DKA)

For hospitalized patients with hyperglycemia without DKA/HHS:

• Start at 0.05 units/kg/hour (approximately 3.5 units/hour for a 70 kg patient) 1
• Target glucose range: 150-200 mg/dL in most hospitalized patients 1

Dosing based on patient characteristics:

• Insulin-naive or low-dose patients: 0.3-0.5 units/kg/day total daily dose, with half as basal insulin 4
• High-risk patients (elderly >65 years, renal failure, poor oral intake): use lower doses of 0.1-0.25 units/kg/day 4
• Patients on high home doses (≥0.6 units/kg/day): reduce total daily dose by 20% to prevent hypoglycemia 4

Transition to Subcutaneous Insulin

Critical timing considerations:

• Continue IV insulin until patient is stable for at least 24 hours and able to resume oral feeding 5, 1
• Stop IV insulin when infusion rate is ≤0.5 units/hour 5, 1
• If infusion rate is ≥5 units/hour, this indicates major insulin resistance – leave syringe in place 5

Calculating subcutaneous dose:

• Total subcutaneous daily dose = 50-80% of the 24-hour IV insulin requirement 5, 1
• Distribute as 50% basal (long-acting) insulin and 50% prandial (rapid-acting) insulin 5, 1
• Administer first subcutaneous basal insulin dose immediately before stopping IV infusion to prevent rebound hyperglycemia 1

The most widely used transition model recommends that half of the total IV insulin dose corresponds to slow insulin, the other half to ultra-rapid analogue 5. Some groups recommend giving 80% of the IV dose as slow insulin and adding ultra-rapid insulin at the first meal 5.

Common Pitfalls to Avoid

• Never stop IV insulin abruptly – overlap with subcutaneous basal insulin is essential to prevent rebound hyperglycemia 1
• Don't rely on urine ketones to monitor DKA resolution – use venous pH and anion gap instead 1
• Avoid starting insulin before correcting hypokalemia – this is the most dangerous error 1
• Don't use excessive doses in hypertriglyceridemia treatment – research shows average doses of only 0.07 units/kg/hour on day 1 are effective 6

Monitoring Requirements

• Check blood glucose hourly during active titration 1
• Monitor serum potassium every 2-4 hours during DKA/HHS treatment 1
• Assess for hypoglycemia risk, particularly with higher insulin doses 1
• Watch for signs of overbasalization if transitioning to subcutaneous therapy (bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia, high glucose variability) 4