In an adult hospitalized patient (≥18 years) with type 1 or type 2 diabetes or stress‑induced hyperglycemia who is not on a scheduled insulin regimen, how should sliding‑scale insulin be dosed?

Sliding-Scale Insulin Should Not Be Used as Monotherapy in Hospitalized Adults

Sliding-scale insulin (SSI) as the sole insulin regimen is ineffective and strongly condemned by all major diabetes guidelines; hospitalized adults with diabetes requiring insulin should receive a scheduled basal-bolus regimen with correction doses as adjuncts only. 1, 2

Why SSI Monotherapy Fails

• SSI treats hyperglycemia reactively—only after it occurs—resulting in dangerous glucose fluctuations rather than stable control 1, 2
• Only 38% of patients on SSI alone achieve mean glucose <140 mg/dL, compared to 68% with basal-bolus therapy, with no difference in hypoglycemia rates 1, 2, 3
• Meta-analysis of 11 randomized trials (1,322 patients) demonstrates SSI provides no benefit in glucose control but significantly increases hyperglycemic events 3
• Retrospective data show SSI is subtherapeutic after 84% of injections, with glucose remaining elevated despite treatment 4

The Correct Approach: Basal-Bolus with Correction Doses

Initial Dosing Algorithm

For insulin-sensitive patients (standard risk):

• Start with 0.3–0.5 units/kg/day total daily dose 1, 2
• Give 50% as basal insulin once daily (glargine, detemir, or degludec) 1, 2
• Give 50% as prandial insulin divided equally among three meals using rapid-acting analogs (lispro, aspart, or glulisine) 1, 2

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

• Start with 0.1–0.25 units/kg/day total daily dose 1, 2
• Use the same 50:50 basal:prandial split 1, 2

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

• Reduce total daily dose by 20% upon admission to prevent hypoglycemia 1, 2

Correction (Sliding-Scale) Dosing—As Adjunct Only

Correction doses supplement scheduled insulin, never replace it: 1, 2

• Add 2 units of rapid-acting insulin when pre-meal glucose >250 mg/dL (13.9 mmol/L) 1
• Add 4 units of rapid-acting insulin when pre-meal glucose >350 mg/dL (19.4 mmol/L) 1
• Administer 0–15 minutes before meals for optimal effect 1
• Never give rapid-acting insulin at bedtime as a sole correction dose—this markedly increases nocturnal hypoglycemia risk 1, 2

Monitoring Frequency

• Check point-of-care glucose immediately before each meal and at bedtime for patients eating regular meals 1
• For patients with poor intake or NPO, check glucose every 4–6 hours 1, 2

Daily Titration Protocol

Basal insulin adjustment (every 3 days):

• Increase by 2 units if fasting glucose 140–179 mg/dL 1
• Increase by 4 units if fasting glucose ≥180 mg/dL 1
• Target fasting glucose 80–130 mg/dL 1

Prandial insulin adjustment (every 3 days):

• Increase by 1–2 units (or 10–15%) based on 2-hour post-meal glucose 1
• Target postprandial glucose <180 mg/dL 1

If hypoglycemia occurs:

• Reduce the implicated dose by 10–20% immediately 1

Special Populations

Patients with Poor Oral Intake or NPO

• Use basal-plus-correction regimen (basal insulin with correction doses only, no scheduled prandial) 1, 2
• Start with 0.1–0.25 units/kg/day as basal insulin 1, 2
• Check glucose every 4–6 hours 1, 2
• If oral intake decreases after starting basal-bolus, immediately reduce total daily insulin to 0.1–0.15 units/kg/day given primarily as basal 1

Diet-Controlled Type 2 Diabetes (Exception)

This is the ONLY scenario where SSI alone may be appropriate: 5

• Patients managing diabetes with diet alone at home typically have adequate beta-cell function and may not require scheduled basal insulin initially 5
• Begin with SSI alone and monitor before meals and at bedtime 5
• Add basal insulin (0.1–0.25 units/kg/day) only if glucose consistently remains >180 mg/dL despite corrections 5
• This approach avoids unnecessary hypoglycemia risk (4–6 times higher with basal-bolus in patients not requiring insulin at home) 5

Type 1 Diabetes

• Never use SSI as monotherapy—this can precipitate diabetic ketoacidosis 1
• Always require basal-bolus therapy from the outset 1

Critical Pitfalls to Avoid

• Never continue unchanged SSI regimens when glucose remains uncontrolled—this is the most frequent error in inpatient insulin management 1, 2
• Never use premixed insulin (70/30) in hospitalized patients—randomized trials show unacceptably high hypoglycemia rates compared to basal-bolus 1, 2
• Never delay transition to scheduled insulin when glucose values are consistently >250 mg/dL 1
• Never rely solely on correction doses when frequent corrections are needed—this signals inadequate scheduled insulin; increase basal or prandial components instead 1
• Never give rapid-acting insulin at bedtime as a sole correction—nocturnal hypoglycemia risk is markedly elevated 1, 2

Expected Outcomes

• With proper basal-bolus therapy, 68% of patients achieve mean glucose <140 mg/dL versus only 38% with SSI alone 1, 2, 3
• Hypoglycemia rates are comparable between basal-bolus and SSI when properly implemented 1, 6, 3
• Recent RCT demonstrates that among patients already on optimal basal-bolus regimens, intensive correction (for glucose >140 mg/dL) provides no additional benefit over nonintensive correction (for glucose >260 mg/dL) 6