When should Actrapid (regular insulin) be administered according to a sliding‑scale protocol in adult in‑patients with type 1 or type 2 diabetes?

Sliding-Scale Insulin Should Be Abandoned as Monotherapy in Hospitalized Patients

Sliding-scale insulin (SSI) as the sole insulin regimen is ineffective and should not be used for hospitalized adults with established diabetes requiring insulin therapy. Instead, implement a scheduled basal-bolus insulin regimen with correction doses as an adjunct 1, 2, 3.

Why Sliding-Scale Monotherapy Fails

• SSI treats hyperglycemia reactively after it has already occurred rather than preventing it, leading to dangerous glucose fluctuations that exacerbate both hyper- and hypoglycemia 1, 3.
• Only 38% of patients on SSI alone achieve mean blood glucose <140 mg/dL, compared to 68% with basal-bolus therapy—with no difference in hypoglycemia rates between the two approaches 1, 2.
• SSI regimens prescribed on admission typically continue unchanged throughout hospitalization even when control remains poor, perpetuating inadequate glycemic management 1, 3.
• Meta-analysis of randomized controlled trials demonstrates that SSI provides no benefits in blood glucose control but is associated with significantly higher mean glucose levels and increased hyperglycemic events 4.

The Correct Approach: Scheduled Basal-Bolus Insulin

Initial Dosing Algorithm

For insulin-naïve or low-dose patients:

• Start with total daily dose of 0.3–0.5 units/kg/day, divided 50% as basal insulin (once daily) and 50% as prandial insulin (distributed across three meals) 2, 3, 5.

For high-risk patients (elderly >65 years, renal failure, poor oral intake):

• Use lower starting dose of 0.1–0.25 units/kg/day to prevent hypoglycemia 2, 3, 5.

For patients on high home insulin doses (≥0.6 units/kg/day):

• Reduce total daily dose by 20% upon hospitalization to prevent hypoglycemia 2, 3.

Correction Insulin: The Proper Role of "Sliding Scale"

Correction doses should supplement—never replace—scheduled basal and prandial insulin 1, 2, 3.

• Add 2 units of rapid-acting insulin when pre-meal glucose >250 mg/dL 2.
• Add 4 units of rapid-acting insulin when pre-meal glucose >350 mg/dL 2.
• If correction doses are frequently required, increase the appropriate scheduled insulin doses rather than relying on reactive corrections 1, 2.

Monitoring Requirements

• Check point-of-care glucose immediately before each meal and at bedtime for patients eating regular meals 2.
• For patients with poor intake or NPO status, check glucose every 4–6 hours 2.

Titration Protocol

Basal insulin adjustment:

• Increase by 2 units every 3 days if fasting glucose is 140–179 mg/dL 2.
• Increase by 4 units every 3 days if fasting glucose is ≥180 mg/dL 2.
• Target fasting glucose: 80–130 mg/dL 2.

Prandial insulin adjustment:

• Increase by 1–2 units (or 10–15%) every 3 days based on 2-hour postprandial glucose 2.
• Target postprandial glucose: <180 mg/dL 2.

Rare Acceptable Uses of SSI

SSI might be appropriate only in these limited scenarios 3:

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

Even in these situations, transition to scheduled insulin if hyperglycemia persists or worsens 3.

Critical Pitfalls to Avoid

• Never use SSI as monotherapy in type 1 diabetes—this can precipitate diabetic ketoacidosis 5.
• Never continue SSI unchanged when blood glucose remains poorly controlled—this is the most common error in hospital insulin management 1, 3.
• Never give rapid-acting insulin at bedtime as a sole correction dose—this markedly increases nocturnal hypoglycemia risk 2.
• Avoid premixed insulin (70/30) in hospitals—it causes unacceptably high hypoglycemia rates 2, 3.

Clinical Outcomes

Basal-bolus therapy with correction doses (not SSI monotherapy) achieves:

• Mean blood glucose <140 mg/dL in 68% of patients vs. 38% with SSI alone 1, 2.
• Reduced hospital complications including postoperative wound infections and acute renal failure 3.
• No increase in hypoglycemia when properly implemented 1, 2.