How to transition an adult patient with type 2 diabetes and insulin resistance from Lantus (insulin glargine) and sliding scale insulin to a new insulin regimen?

Transitioning from Lantus and Sliding Scale to a Scheduled Basal-Bolus Insulin Regimen

Discontinue sliding scale insulin as monotherapy immediately and transition to a scheduled basal-bolus regimen, as sliding scale insulin alone is explicitly condemned by all major diabetes guidelines and leads to dangerous glucose fluctuations with only 38% of patients achieving adequate glycemic control compared to 68% with basal-bolus therapy. 1, 2, 3

Why Sliding Scale Insulin Fails

• Sliding scale insulin treats hyperglycemia reactively after it has already occurred rather than preventing it, resulting in rapid glucose fluctuations and treatment failures 1, 2, 3
• The American Diabetes Association and all major diabetes societies condemn the use of sliding scale insulin as monotherapy in patients with established insulin requirements 1, 2
• Randomized trials consistently demonstrate that basal-bolus regimens reduce hospital complications (postoperative wound infection, pneumonia, bacteremia, acute renal and respiratory failure) compared to sliding scale alone 1

The Correct Approach: Scheduled Basal-Bolus Insulin

Step 1: Calculate Total Daily Insulin Dose

For patients currently on Lantus plus sliding scale:

• Add up the current Lantus dose PLUS the average total daily sliding scale insulin used over the past 24-48 hours to estimate total daily dose (TDD) 1, 2
• If the patient was insulin-naive or on minimal insulin before, start with 0.3-0.5 units/kg/day as TDD for moderate hyperglycemia, or 0.4-0.6 units/kg/day for severe uncontrolled hyperglycemia (HbA1c ≥9% or glucose consistently >250 mg/dL) 1, 4

Step 2: Split the Total Daily Dose

Use a 50:50 split between basal and prandial insulin: 1, 2

• 50% as basal insulin (Lantus): Give once daily at the same time each day, typically at bedtime 1, 4
• 50% as prandial insulin: Divide equally among three meals using rapid-acting insulin (lispro, aspart, or glulisine) given 0-15 minutes before meals 1, 5

Example calculation for a 70 kg patient with severe hyperglycemia:

• TDD = 0.4 units/kg/day × 70 kg = 28 units/day
• Basal (Lantus): 14 units once daily at bedtime
• Prandial: 14 units ÷ 3 meals = approximately 5 units before each meal 1, 4

Step 3: Add Correction Insulin

Implement a correction insulin protocol using the same rapid-acting insulin as prandial doses: 1, 2

• For premeal glucose >250 mg/dL: add 2 units of rapid-acting insulin to the scheduled prandial dose 1, 2
• For premeal glucose >350 mg/dL: add 4 units of rapid-acting insulin to the scheduled prandial dose 1, 2
• Critical distinction: Correction insulin is an ADJUNCT to scheduled basal-bolus therapy, not a replacement 1, 2

Step 4: Titration Protocol

Basal insulin (Lantus) titration based on fasting glucose: 1, 4

• Target fasting glucose: 80-130 mg/dL 1
• If fasting glucose 140-179 mg/dL: increase Lantus by 2 units every 3 days 1, 4
• If fasting glucose ≥180 mg/dL: increase Lantus by 4 units every 3 days 1, 4
• If fasting glucose <80 mg/dL on more than 2 occasions per week: decrease Lantus by 2 units 1, 4

Prandial insulin titration based on postprandial glucose: 1

• Target postprandial glucose: <180 mg/dL 1, 2
• Increase prandial dose by 1-2 units or 10-15% every 3 days if 2-hour postprandial glucose consistently exceeds 180 mg/dL 1
• If hypoglycemia occurs without clear cause, reduce the corresponding dose by 10-20% immediately 1

Step 5: Monitoring Requirements

• Check blood glucose before each meal and at bedtime during the titration phase 1, 2
• For patients with poor oral intake, check glucose every 4-6 hours 1, 2
• Daily fasting blood glucose monitoring is essential during basal insulin titration 1, 4
• Reassess HbA1c every 3 months during intensive titration 1

Critical Threshold: When Basal Insulin Exceeds 0.5 units/kg/day

When Lantus dose approaches 0.5-1.0 units/kg/day without achieving glycemic targets, this signals "overbasalization"—continuing to escalate basal insulin leads to increased hypoglycemia risk without improved control. 1, 4

Clinical signs of overbasalization include: 1, 4

• Basal insulin dose >0.5 units/kg/day
• Bedtime-to-morning glucose differential ≥50 mg/dL (indicating excessive basal insulin causing overnight glucose drops)
• Episodes of hypoglycemia
• High glucose variability throughout the day

At this threshold, intensify prandial insulin coverage rather than continuing to escalate basal insulin. 1, 4

Foundation Therapy: Continue Metformin

• Continue metformin at maximum tolerated dose (up to 2000-2550 mg daily) unless contraindicated, as this combination provides superior glycemic control with reduced insulin requirements and less weight gain 1, 4
• Consider discontinuing sulfonylureas when advancing beyond basal-only insulin to prevent hypoglycemia 1

Special Populations Requiring Dose Adjustments

High-risk patients (elderly >65 years, renal impairment, poor oral intake): 1, 2

• Start with lower doses: 0.1-0.25 units/kg/day as TDD
• Use more conservative titration: increase by 1-2 units every 3-7 days
• Target less stringent glucose goals: 90-150 mg/dL preprandial 2

Patients on corticosteroids: 2, 6

• Increase prandial and correction insulin by 40-60% or more in addition to basal insulin
• Consider NPH insulin twice daily instead of Lantus to match the glucocorticoid-induced hyperglycemia pattern 6

Patients with CKD Stage 5: 4

• Reduce total daily insulin dose by 50% for type 2 diabetes, or 35-40% for type 1 diabetes
• Monitor closely for hypoglycemia as insulin clearance decreases with declining kidney function 4

Common Pitfalls to Avoid

• Never continue sliding scale insulin as monotherapy in patients with established insulin requirements—this approach is definitively shown to be inferior and dangerous 1, 2, 3
• Never delay the transition to scheduled insulin when blood glucose values are consistently >200 mg/dL, as this prolongs exposure to severe hyperglycemia and increases complication risk 1, 2
• Never give rapid-acting insulin at bedtime for correction, as this significantly increases nocturnal hypoglycemia risk 1, 2
• Never discontinue metformin when starting or intensifying insulin unless contraindicated, as this leads to higher insulin requirements and more weight gain 1, 4
• Never continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia with prandial insulin, as this causes overbasalization with increased hypoglycemia and suboptimal control 1, 4
• Do not use premixed insulin (70/30, NovoMix) in hospitalized patients, as randomized trials show unacceptably high rates of iatrogenic hypoglycemia compared to basal-bolus regimens 1, 2

Patient Education Essentials

• Proper insulin injection technique and site rotation 1
• Recognition and treatment of hypoglycemia: treat any glucose <70 mg/dL immediately with 15 grams of fast-acting carbohydrate, recheck in 15 minutes 1, 4
• Self-monitoring of blood glucose: check before each meal and at bedtime during titration 1, 2
• "Sick day" management rules and insulin storage/handling 1
• Timing of rapid-acting insulin: administer 0-15 minutes before meals for optimal postprandial glucose control 1, 5

Expected Outcomes

• With appropriate basal-bolus therapy, 68% of patients achieve mean blood glucose <140 mg/dL versus only 38% with sliding scale alone 1, 2, 3
• HbA1c reduction of 2-3% from baseline is achievable over 3-6 months with proper insulin intensification 1, 4
• Basal-bolus regimens reduce hospital complications with no increased hypoglycemia risk when properly implemented 1, 3