What is the recommended dose of regular insulin for a patient experiencing hyperglycemia?

Regular Insulin Dosing for Hyperglycemia in Hospitalized Patients

For hospitalized patients with hyperglycemia, regular insulin should be administered subcutaneously every 4-6 hours as needed for blood glucose correction, with a typical starting dose of 5 units for every 50 mg/dL increase in blood glucose above 150 mg/dL, up to 20 units for blood glucose of 300 mg/dL. 1

Insulin Initiation Threshold and Target Range

Insulin therapy should be initiated when blood glucose persistently exceeds 180 mg/dL (checked on two occasions), with a target glucose range of 140-180 mg/dL for most critically ill and noncritically ill hospitalized patients. 2

• More stringent goals of 110-140 mg/dL may be appropriate for selected patients (e.g., critically ill postsurgical patients) as long as they can be achieved without significant hypoglycemia 2
• For noncritically ill patients, expert consensus recommends a target range of 100-180 mg/dL 2
• The NICE-SUGAR trial demonstrated that intensive glycemic control (80-110 mg/dL) resulted in significantly higher mortality (27.5% vs 25%) and 10- to 15-fold greater rates of hypoglycemia compared to moderate targets 2

Regular Insulin Dosing Protocols

Standard Correction Dosing for Non-DKA Hyperglycemia

For adult hospitalized patients who are NPO (nothing by mouth), supplemental subcutaneous regular insulin can be given in 5-unit increments for every 50 mg/dL increase in blood glucose above 150 mg/dL, up to 20 units for blood glucose of 300 mg/dL. 1

• Regular insulin should be administered subcutaneously every 4-6 hours as needed for blood glucose correction 1
• Rapid-acting insulin analogs can be administered every 4 hours as an alternative 1
• For patients on continuous, bolus enteral, or parenteral feedings, regular insulin every 6 hours or rapid-acting insulin every 4 hours can be used 1

DKA-Specific Dosing

For mild DKA, an initial "priming" dose of regular insulin of 0.4-0.6 units/kg body weight should be given, followed by 0.1 unit/kg regular insulin subcutaneously or intramuscularly every hour. 1

• For moderate to severe DKA, continuous intravenous insulin infusion is the preferred treatment, with an initial IV bolus of regular insulin at 0.15 units/kg body weight, followed by continuous infusion at 0.1 unit/kg/hour 1
• Blood should be drawn every 2-4 hours for determination of serum electrolytes, glucose, blood urea nitrogen, creatinine, osmolality, and venous pH 1
• Criteria for resolution of DKA includes glucose <200 mg/dL, serum bicarbonate ≥18 mEq/L, and venous pH of ≥7.3 1

Scheduled Insulin Regimens vs. Sliding Scale Monotherapy

Sliding scale insulin as monotherapy is explicitly condemned by all major diabetes guidelines and shown to be ineffective—scheduled basal-bolus regimens are strongly preferred for adequate glycemic control. 3, 1, 4

Recommended Scheduled Regimens

For hospitalized patients who are insulin-naive or on low-dose insulin, start with a total daily dose of 0.3-0.5 units/kg, with half as basal insulin and half as prandial/correction insulin. 3

• For patients on high-dose home insulin (≥0.6 units/kg/day), reduce the total daily dose by 20% to prevent hypoglycemia 3
• Lower doses (0.1-0.25 units/kg/day) are recommended for high-risk patients, such as the elderly (>65 years), those with renal failure, or poor oral intake 3
• For patients with poor or no oral intake, a single dose of long-acting insulin plus correction insulin is preferred over basal-bolus regimens 5

Critical Considerations Before Dosing

Always assess for diabetic ketoacidosis before administering correction insulin alone—if DKA is present, continuous intravenous insulin infusion is required rather than subcutaneous dosing. 1

• For insulin-naive patients with blood glucose >300 mg/dL, a basal-plus regimen is recommended rather than correction insulin alone, with an initial total daily dose of 0.3-0.5 units/kg 1
• Patients already on home insulin doses ≥0.6 units/kg/day should have a 20% reduction in total daily dose during hospitalization to prevent hypoglycemia 1

Monitoring Requirements

Point-of-care glucose monitoring should be performed before meals for patients who are eating, and every 4-6 hours for those not eating. 2

• More frequent monitoring ranging from every 30 minutes to every 2 hours is required for safe use of intravenous insulin 2
• During DKA management, blood should be drawn every 2-4 hours for determination of serum electrolytes and glucose 1

Transition to Maintenance Therapy

When transitioning from IV to subcutaneous insulin, subcutaneous insulin must be administered 1-2 hours before discontinuing the insulin drip to ensure adequate overlap and prevent rebound hyperglycemia. 1

• The effects of regular insulin administered via continuous intravenous infusion cease rapidly once the infusion is stopped, typically within 10-20 minutes 1
• When the patient is able to eat, transition to a multiple-dose schedule using a combination of short/rapid-acting and intermediate/long-acting insulin 1
• Never discontinue IV insulin without prior subcutaneous dosing, especially in patients with type 1 diabetes or DKA, as this can precipitate rapid metabolic decompensation 1

Common Pitfalls to Avoid

Do not rely solely on sliding scale insulin for glycemic control—this treats hyperglycemia reactively after it occurs rather than preventing it, leading to dangerous glucose fluctuations. 3, 1

• Avoid "stacking" correction doses, as insulin from the previous dose may still be active 1
• For patients with risk factors for hypoglycemia (age >65 years, renal failure, poor oral intake), reduce the maximum dose of regular insulin 1
• Do not use sliding scale insulin alone during transition from IV insulin; a basal-bolus regimen is required for adequate glycemic control 1
• Account for the patient's nutritional status when calculating doses, as insulin requirements differ significantly between NPO, enteral, and oral feeding states 1