What is the proper dosing for human regular insulin?

Human Regular Insulin Dosing Guidelines

The proper dosing for human regular insulin should follow a structured approach based on clinical setting, with initial basal insulin starting at 10 units per day or 0.1-0.2 units/kg/day, and prandial insulin starting at 4 units, 0.1 units/kg, or 10% of the basal dose, with systematic titration based on blood glucose monitoring. 1, 2

Initial Dosing Considerations

• For insulin-naïve patients with type 2 diabetes, start basal insulin at 10 units per day or 0.1-0.2 units/kg/day 1, 2
• For prandial (mealtime) insulin, start with 4 units per dose, 0.1 units/kg, or 10% of the basal insulin dose 3
• Total daily insulin requirements typically range from 0.3-0.5 units/kg for insulin-naive patients 2
• When adding prandial insulin to a regimen with existing basal insulin, consider reducing the basal dose by 4 units or 10% if A1C is <8% to prevent hypoglycemia 3

Basal-Bolus Regimen

• Divide total daily insulin dose with approximately 50% as basal insulin and 50% as prandial insulin 2
• Titrate basal insulin by increasing 2 units every 3 days to reach fasting glucose target without hypoglycemia 1
• For hypoglycemia, determine the cause and lower the dose by 10-20% if no clear reason is found 1, 2
• Prandial insulin should be initiated with one dose at the largest meal or the meal with the greatest postprandial glucose excursion 1, 3

Hospital Setting Considerations

• For hospitalized patients, a basal-bolus insulin regimen is preferred over sliding-scale insulin (SSI) alone for better glycemic control 1, 4
• For patients receiving enteral nutrition, use basal insulin along with regular insulin every 6 hours or rapid-acting insulin every 4 hours 1
• Start with 1 unit per 10-15 g of carbohydrate for nutritional insulin requirements in patients receiving enteral or parenteral nutrition 1
• For patients with renal insufficiency, consider reducing the initial insulin dose by 50% (to 0.25 units/kg/day) to reduce hypoglycemia risk 5

Sliding Scale Protocol (When Needed)

• For premeal glucose >250 mg/dL, add 2 units of regular insulin 1, 3
• For premeal glucose >350 mg/dL, add 4 units of regular insulin 1, 3
• Avoid using sliding scale as the sole insulin regimen as it is less effective than basal-bolus approaches 4, 6
• In hospitalized patients, target blood glucose <180 mg/dL rather than tighter control to minimize both hyperglycemia and hypoglycemia 7

Special Populations

• For older adults, use a simplified approach with lower targets (90-150 mg/dL) to reduce hypoglycemia risk 1
• In frail elderly patients, consider discontinuing sliding scale when not needed daily 1, 3
• Avoid using rapid-acting insulin at bedtime in older adults to prevent nocturnal hypoglycemia 1
• For patients on glucocorticoids, additional NPH insulin (0.1-0.3 units/kg/day) may be needed to control hyperglycemia 2

Monitoring and Adjustment

• Assess adequacy of insulin dose at every visit 1
• If 50% of blood glucose values are above target, increase dose by 1-2 units or 10-15% 1, 3
• Decrease dose if more than 2 glucose values per week are below target range 1, 3
• For stepwise intensification, progress from one prandial injection to multiple daily injections as needed 1

Common Pitfalls to Avoid

• Relying solely on sliding scale insulin, which is less effective than basal-bolus regimens 4, 6
• Failing to adjust insulin doses regularly, leading to persistent hyperglycemia 1, 2
• Using the same insulin regimen for all patients regardless of clinical factors like renal function or age 1, 5
• Targeting overly tight glucose control in hospitalized patients, which increases hypoglycemia risk without improving outcomes 7