Can I administer extra units of sliding scale (Regular or Aspart) insulin?

Can You Give Extra Units of Sliding Scale Insulin?

No, you should not rely on sliding scale insulin alone or give "extra units" as your primary approach—instead, use a scheduled basal-bolus insulin regimen with correction doses as an adjunct, not as monotherapy. 1, 2

Why Sliding Scale Insulin Alone Fails

The American Diabetes Association explicitly states that sole use of sliding scale insulin in the inpatient hospital setting is strongly discouraged. 1 The evidence is clear:

• Sliding scale insulin is a reactive approach that treats hyperglycemia after it has already occurred, leading to rapid blood glucose fluctuations that exacerbate both hyperglycemia and hypoglycemia 1, 2
• Only 38% of patients achieve mean blood glucose <140 mg/dL with sliding scale insulin alone versus 68% with basal-bolus regimens 1, 2
• Meta-analysis of 11 randomized controlled trials (1,322 patients) showed sliding scale insulin provided no benefits in blood glucose control and was associated with significantly increased hyperglycemic events 3
• Sliding scale regimens prescribed on admission are typically used throughout hospitalization without modification, even when control remains poor 1, 2

The Correct Approach: Scheduled Insulin with Correction Doses

Use correction-dose insulin as an important adjunct to scheduled basal-bolus insulin, not as standalone therapy. 1 Here's the proper framework:

For Patients Eating Well:

• Start with total daily dose of 0.3-0.5 units/kg/day 2, 4
• Allocate 50% to basal insulin (once daily) and 50% to rapid-acting prandial insulin (before meals) 2, 4
• Add correction doses of rapid-acting insulin for hyperglycemia 2

For Patients with Poor Oral Intake or NPO:

• Use basal insulin or basal-plus regimen (0.1-0.25 units/kg/day basal insulin) 2
• Add correction doses of rapid-acting insulin every 4-6 hours as needed 1
• Critical: Patients with type 1 diabetes must continue basal insulin even if NPO to prevent diabetic ketoacidosis 1

When Correction Doses Signal a Problem

If correction doses are frequently required, this indicates your scheduled insulin doses are inadequate and must be increased. 1, 2 The correction dose is a dose-finding strategy—not a long-term solution. 1

Limited Acceptable Uses of Sliding Scale Insulin

The American Diabetes Association suggests sliding scale insulin might be acceptable only in these specific scenarios:

• Patients with mild stress hyperglycemia without pre-existing diabetes 2
• Patients with well-controlled diabetes (HbA1c <7%) on minimal home therapy who have mild hyperglycemia during hospitalization 2
• Patients who are NPO with no nutritional replacement and only mild hyperglycemia 2
• Patients who are new to steroids or tapering steroids 2

Safety Considerations

• Basal-bolus regimens carry 4-6 times higher hypoglycemia risk than sliding scale insulin alone (risk ratio 5.75,95% CI 2.79-11.83) 4
• Review and adjust the treatment regimen after any glucose <70 mg/dL 4
• For patients on high home insulin doses (≥0.6 units/kg/day), reduce total daily dose by 20% during hospitalization to prevent hypoglycemia 2, 4

Clinical Evidence

A landmark randomized controlled trial in general surgery patients with type 2 diabetes demonstrated that basal-bolus treatment improved glycemic control and reduced hospital complications (including postoperative wound infections and acute renal failure) compared with sliding scale insulin alone. 1, 4 The pharmacodynamics of rapid-acting insulin aspart show maximum glucose-lowering effect between 1-3 hours after injection with duration of action 3-5 hours, making it appropriate for correction doses when used as part of a comprehensive regimen. 5