What is sliding‑scale insulin and is it still appropriate for managing hyperglycaemia in hospitalized adult patients with diabetes today?

What is Sliding-Scale Insulin and Is It Still Appropriate Today?

Sliding-scale insulin (SSI) is a reactive approach that administers short- or rapid-acting insulin in response to elevated blood glucose rather than pre-emptively, and it should NOT be used as the sole treatment for hospitalized patients with established diabetes—current guidelines strongly discourage this outdated practice. 1, 2

Definition and Mechanism

Sliding-scale insulin is a dosing strategy where insulin is given after hyperglycemia occurs, typically using a predetermined algorithm that increases insulin doses based on point-of-care glucose readings 3. For example, a typical SSI protocol might prescribe 2 units of rapid-acting insulin for glucose >250 mg/dL and 4 units for glucose >350 mg/dL 2.

The fundamental problem with SSI is that it treats hyperglycemia reactively rather than preventing it, leading to dangerous glucose fluctuations and poor metabolic control 2, 4.

Current Evidence Against SSI Monotherapy

Efficacy Data

The evidence against SSI as monotherapy is overwhelming:

• Only 38% of patients on SSI alone achieve mean blood glucose <140 mg/dL, compared to 68% with basal-bolus therapy 2, 5
• SSI results in significantly higher mean blood glucose levels (27.33 mg/dL higher) and increased hyperglycemic events compared to scheduled insulin regimens 4
• A randomized controlled trial demonstrated that basal-bolus treatment improved glycemic control and reduced hospital complications compared to SSI in general surgery patients with type 2 diabetes 1
• Meta-analysis of 11 RCTs involving 1,322 patients found SSI provided no benefits in blood glucose control but was accompanied by increased hyperglycemic events 4

Safety Concerns

• SSI has been associated with poor glycemic control and deleterious effects despite over 80 years of use without strong supporting evidence 3
• The practice leads to widely variable, often ineffectual outcomes prone to deficiencies in monitoring and documentation 6
• In one study, insulin effects were subtherapeutic after 84% of SSI injections, with glucose levels remaining persistently elevated 6

When SSI May Be Acceptable (Very Limited Scenarios)

SSI alone may be appropriate ONLY in these specific situations:

• Patients without diabetes who develop mild stress hyperglycemia during hospitalization 2, 7
• Diet-controlled type 2 diabetes patients (not on medications at home) who typically have adequate beta-cell function and do not require scheduled basal insulin 7
• In these limited cases, start with SSI and add basal insulin only if blood glucose consistently exceeds 180 mg/dL despite correctional insulin 7

Recommended Approach Instead of SSI

For Non-Critically Ill Hospitalized Patients

The preferred regimen is basal-bolus-correction insulin:

• Basal insulin: 50% of total daily dose given once or twice daily (glargine, detemir, or degludec) 2
• Prandial insulin: 50% of total daily dose divided before meals using rapid-acting analogs 2
• Correction insulin: Rapid-acting insulin for hyperglycemia as needed, in addition to scheduled doses 2

Initial Dosing

• For insulin-naive patients: Start with 0.3-0.5 units/kg/day total dose, split 50% basal/50% prandial 2
• For high-risk patients (elderly >65 years, renal failure, poor oral intake): Use lower doses of 0.1-0.25 units/kg/day 2

Glycemic Targets

• Premeal glucose: <140 mg/dL 2
• Random glucose: <180 mg/dL for non-critically ill patients 2
• Critically ill patients: 140-180 mg/dL 2

Critical Pitfalls to Avoid

• Never use SSI as monotherapy for patients with established insulin requirements—this is associated with clinically significant hyperglycemia and poor outcomes 2
• Never use SSI alone in patients with type 1 diabetes 2
• Never continue SSI as the sole treatment for patients with type 2 diabetes on insulin at home—they require scheduled basal insulin 2
• Do not delay transition to scheduled insulin when SSI proves inadequate—prolonged use of SSI as sole treatment is strongly discouraged 1

The Bottom Line

Sliding-scale insulin is an outdated, ineffective practice that has persisted for over 80 years despite lack of evidence 3. Current guidelines from the American Diabetes Association explicitly state that prolonged use of SSI as the sole treatment of hyperglycemic inpatients is strongly discouraged 1. The only acceptable use is as correction insulin added to a scheduled basal-bolus regimen, or in very limited scenarios of mild stress hyperglycemia in patients without established diabetes 2, 7.

If you encounter a hospitalized patient on SSI monotherapy, transition them immediately to a scheduled basal-bolus regimen to achieve better glycemic control and reduce complications 1, 2.