What is a sliding scale in diabetes management?

What is Sliding Scale Insulin in Diabetes Management

Sliding scale insulin is a reactive insulin regimen that administers correction doses of short-acting insulin based on current blood glucose readings according to a predetermined table or scale, but it should be strongly discouraged as the sole treatment approach for hospitalized patients with diabetes. 1

Definition and Mechanism

Sliding scale insulin (SSI) is a method where insulin doses are assigned to treat prespecified glucose ranges on a scale or table. 1 The regimen provides correction insulin alone—typically short- or rapid-acting insulin—in response to elevated blood glucose measurements, without providing basal insulin coverage. 1

Why Sliding Scale Insulin Fails

The fundamental problem with SSI is that it treats hyperglycemia reactively rather than proactively, leading to rapid blood glucose fluctuations that worsen both hyperglycemia and hypoglycemia. 2, 3

Key limitations include:

• SSI does not provide favorable in-hospital outcomes compared to regimens using basal and preprandial insulin 1
• Mean blood glucose levels are significantly higher with SSI (27.33 mg/dL higher) compared to non-sliding-scale regimens 4
• Only 38% of patients achieve glycemic control (mean blood glucose <140 mg/dL) with SSI alone versus 68% with basal-bolus regimens 2
• SSI regimens are often continued throughout hospitalization without modification, even when control remains poor 2, 3, 5
• Documentation and execution deficiencies occur in approximately 30% of anticipated care points 5

Clinical Evidence Against SSI

Research consistently demonstrates SSI's ineffectiveness:

• A meta-analysis of 11 randomized controlled trials involving 1,322 patients found no benefit in blood glucose control with SSI, but rather an increased incidence of hyperglycemic events 4
• In one study, 84% of SSI injections resulted in subtherapeutic effects with persistently elevated glucose levels 5
• Overall glycemic control remained poor in 51-68% of patients on any given day when treated with SSI 5
• Adding SSI to routine diabetes medications provided no reduction in hyperglycemia, hypoglycemia, or length of hospitalization 6

When SSI Might Be Acceptable (Very Limited Circumstances)

The American Diabetes Association identifies only narrow situations where SSI alone may be appropriate: 2, 7

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

Recommended Alternative: Basal-Bolus or Basal-Plus Regimens

Instead of SSI, use basal insulin with preprandial correction doses or a full basal-bolus regimen, which produces better glycemic control and fewer treatment failures. 1

For patients with good oral intake:

• Start with 0.3-0.5 units/kg total daily dose, divided 50% basal (once daily) and 50% prandial (before meals) 2, 3
• This basal-bolus approach reduces risk for postsurgical complications 1

For patients with poor oral intake or NPO:

• Use basal-plus regimen: 0.1-0.25 units/kg/day of basal insulin plus correction doses of rapid-acting insulin 2, 3, 7

Safety considerations:

• For patients on high insulin doses at home (≥0.6 units/kg/day), reduce total daily dose by 20% during hospitalization to prevent hypoglycemia 2, 3, 7
• Basal-bolus regimens carry 4-6 times higher risk of hypoglycemia (RR 5.75) compared to SSI, but provide superior overall glycemic control 7

Common Pitfalls to Avoid

• Never use SSI alone as the initial approach for patients with type 1 diabetes—this is dangerous 2, 3
• Do not continue the same SSI regimen throughout hospitalization without modification despite poor control 2, 3, 5
• Avoid premixed insulin (70/30) in hospitals due to unacceptably high hypoglycemia rates 2, 3
• Do not rely on SSI's perceived ease of implementation—it creates glucose variability rather than stable control 3