Can I take Lantus (insulin glargine) twice daily and still take insulin lispro on a sliding scale three times a day before meals and at bedtime (TIDAC)?

Can You Take Lantus Twice Daily and Still Take Insulin Lispro on Sliding Scale TIDAC?

Yes, you can take Lantus (insulin glargine) twice daily and combine it with insulin lispro on a sliding scale before meals and at bedtime, though this represents a suboptimal regimen that should be transitioned to a more physiologic basal-bolus approach for better glycemic control and reduced hypoglycemia risk.

Understanding the Regimen Components

Lantus Twice Daily Dosing

• Lantus is FDA-approved and designed for once-daily administration, providing approximately 24 hours of basal insulin coverage without significant peaks 1
• However, twice-daily Lantus administration is a recognized clinical practice for patients who experience hypoglycemia or inadequate glycemic control with once-daily dosing 2
• Case reports demonstrate that splitting Lantus into twice-daily injections can resolve morning hypoglycemia that persists despite dose titration of once-daily administration 2
• The twice-daily approach may provide more stable insulin levels in patients whose insulin glargine does not maintain full 24-hour coverage 2

Combining with Sliding Scale Lispro

• Sliding scale insulin represents an outdated approach that reacts to hyperglycemia rather than preventing it 3
• The combination of basal insulin (Lantus) with rapid-acting insulin (lispro) is physiologically sound, but scheduled fixed-dose or carbohydrate-counting prandial insulin is superior to sliding scale 4
• When initiating prandial insulin, guidelines recommend starting with 4 units per meal, 0.1 units/kg per meal, or 10% of basal dose per meal rather than reactive sliding scale 4

Why This Regimen Is Problematic

Clinical Inefficiency

• Sliding scale insulin fails to provide adequate postprandial glucose control because it addresses hyperglycemia after it occurs rather than preventing it 3
• This approach leads to glycemic variability and makes achieving HbA1c targets more difficult 5

Increased Hypoglycemia Risk

• Combining twice-daily basal insulin with reactive sliding scale increases unpredictability of insulin action and hypoglycemia risk 1, 2
• The overlapping insulin action from twice-daily Lantus plus variable sliding scale doses creates difficulty in identifying the cause of hypoglycemia 2

Recommended Transition Strategy

Immediate Management

• If currently using this regimen, continue it temporarily while planning transition to avoid abrupt changes that could destabilize glucose control 4
• Monitor blood glucose at least 4 times daily (fasting, before each meal, and bedtime) to identify patterns 3

Optimal Regimen Conversion

• Transition to once-daily Lantus at bedtime or morning (same time each day) at 80-100% of current total daily Lantus dose 1
• Convert sliding scale lispro to scheduled prandial insulin using one of these approaches 4:
  • Start with 4 units before each meal
  • Calculate 0.1 units/kg per meal
  • Use 10% of basal insulin dose per meal
• Begin with single mealtime injection before the largest meal or meal with greatest postprandial excursion, then expand to other meals as needed 4

Medication Adjustments During Transition

• Continue metformin if currently prescribed 4, 6
• Discontinue sulfonylureas to reduce hypoglycemia risk 4, 6
• Discontinue DPP-4 inhibitors as they become redundant with prandial insulin 4, 6

Critical Safety Considerations

Timing Requirements

• Lantus should be administered at the same time each day (morning or bedtime, not both unless specifically indicated) 1, 7
• Rapid-acting lispro should be injected 0-5 minutes before meals, not after eating 4

Common Pitfalls to Avoid

• Do not continue twice-daily Lantus indefinitely without reassessing whether once-daily dosing with proper titration would suffice 1, 2
• Never mix Lantus with other insulins in the same syringe due to its acidic pH 6, 1
• Avoid therapeutic inertia—if this regimen fails to achieve HbA1c targets, intensify to proper basal-bolus rather than continuing to escalate doses 8, 4

Patient Education Requirements

• Teach carbohydrate counting before transitioning from sliding scale to scheduled prandial insulin 4
• Provide hypoglycemia recognition and treatment protocols: 15-20g fast-acting carbohydrate (glucose tablets or 4-6 oz juice) for glucose 55-70 mg/dL 3
• Ensure patients understand the difference between basal and prandial insulin to prevent dosing errors 4

When Twice-Daily Lantus May Be Justified

• Persistent morning hypoglycemia despite dose reduction with once-daily evening Lantus 2
• Inadequate 24-hour coverage demonstrated by elevated pre-dinner or bedtime glucose with once-daily morning Lantus 2
• As a temporary bridge while transitioning between regimens 2

The bottom line: While technically feasible, this combination should be viewed as a transitional regimen requiring optimization to a standard once-daily basal insulin with scheduled (not sliding scale) prandial insulin for improved glycemic control, reduced hypoglycemia, and better quality of life.