Sliding Scale Insulin Should Not Be Used as Monotherapy in Hospitalized Patients
Sliding scale insulin (SSI) alone is strongly discouraged for hospitalized patients with diabetes and should be replaced with a basal-bolus or basal-plus regimen, except in very limited circumstances such as patients without pre-existing diabetes who develop mild stress hyperglycemia. 1, 2, 3
Why Sliding Scale Insulin Fails
Traditional SSI regimens are ineffective and potentially harmful because they:
- Treat hyperglycemia reactively after it has already occurred, rather than preventing it 1, 2
- Lead to rapid blood glucose fluctuations that exacerbate both hyperglycemia and hypoglycemia 1, 3
- Are typically prescribed on admission and continued without modification throughout hospitalization, even when control remains poor 1, 3
- Result in only 38% of patients achieving glycemic control (mean blood glucose <140 mg/dL) compared to 68% with basal-bolus therapy 1, 4
Recommended Alternative: Basal-Bolus or Basal-Plus Regimen
For Insulin-Naive Patients or Those on Low Doses:
Starting dose: 0.3-0.5 units/kg/day total daily dose 2, 3
Distribution:
- 50% as basal insulin (glargine or detemir) given once daily 2, 3
- 50% as rapid-acting insulin (lispro, aspart, or glulisine) divided before three meals 2, 3
Example for a 70 kg patient:
- Total daily dose: 21-35 units
- Basal insulin: 10-18 units once daily
- Rapid-acting insulin: 3-6 units before each meal 3
For High-Risk Patients (Elderly, Renal Failure, Poor Oral Intake):
Use lower doses: 0.1-0.25 units/kg/day 2, 3
For Patients Already on High-Dose Insulin at Home (≥0.6 units/kg/day):
Reduce total daily dose by 20% during hospitalization to prevent hypoglycemia 2, 3
Correction Dose Template (Supplemental to Scheduled Insulin)
Add correction doses of rapid-acting insulin before meals or every 4-6 hours if NPO: 1, 3
- Blood glucose 151-200 mg/dL: 2 units
- Blood glucose 201-250 mg/dL: 4 units
- Blood glucose 251-300 mg/dL: 6 units
- Blood glucose 301-350 mg/dL: 8 units
- Blood glucose >350 mg/dL: 10 units and notify physician 3
Critical point: If correction doses are frequently required, increase the scheduled basal or prandial insulin doses accordingly rather than continuing to rely on corrections 1, 3
Very Limited Acceptable Uses of SSI Alone
SSI as monotherapy may be appropriate only for: 3, 5
- Patients without pre-existing diabetes who develop mild stress hyperglycemia during hospitalization 2, 3, 5
- Patients with well-controlled type 2 diabetes (HbA1c <7%) on diet alone or minimal oral therapy at home who have only mild hyperglycemia 3, 5
- Patients who are NPO with no nutritional replacement and only mild hyperglycemia 3
- Patients who are new to steroids or tapering steroids 3
Evidence Supporting This Approach
The RABBIT 2 trial demonstrated that basal-bolus therapy achieved target blood glucose <140 mg/dL in 66% of patients versus only 38% with SSI, with an overall blood glucose difference of 27 mg/dL (P<0.01) 4. The basal-bolus approach was also associated with reduced complications including postoperative wound infection, pneumonia, bacteraemia, and acute renal failure 2.
Critical Pitfalls to Avoid
- Never use SSI alone in patients with type 1 diabetes - this can lead to diabetic ketoacidosis 3, 6
- Avoid premixed insulin (70/30) in hospitals due to unacceptably high hypoglycemia rates 3, 5
- Do not abruptly discontinue oral medications when starting insulin due to risk of rebound hyperglycemia 7
- Monitor for hypoglycemia: Basal-bolus regimens carry a 4-6 times higher risk of hypoglycemia (blood glucose ≤70 mg/dL) compared to SSI, though severe hypoglycemia rates are similar 5, 8
Target Glucose Range
Aim for 140-180 mg/dL for most hospitalized patients 2