No, Insulin Degludec (Tresiba) is NOT the Same as Insulin Glargine (Lantus/Toujeo)
These are distinct basal insulin analogs with different molecular structures, pharmacokinetic profiles, and clinical characteristics, though both serve the same therapeutic role of providing 24-hour basal insulin coverage. 1, 2
Key Pharmacological Differences
Duration of Action and Stability
- Insulin degludec has an ultra-long duration of action exceeding 42 hours, compared to insulin glargine's approximately 24-hour duration 3, 4
- Degludec demonstrates a flat, stable glucose-lowering profile with significantly less within-patient day-to-day variability than glargine 3
- The half-life of degludec is 17-21 hours, roughly double the duration of action of insulin glargine 4
Molecular Mechanism
- Degludec is created by coupling Des-B30 threonine insulin to fatty acid side chains; after injection, it self-associates and precipitates in subcutaneous tissue, with continuous slow dissociation of insulin monomers from this depot 4
- Insulin glargine uses a different mechanism involving acidic pH formulation that precipitates in subcutaneous tissue 5
Clinical Performance Differences
Glycemic Control
- Both insulins achieve similar HbA1c reductions and are considered non-inferior to each other in head-to-head trials 2, 6
- In type 1 diabetes trials, degludec achieved HbA1c of 7.3% versus 7.3% with glargine U-100 at 52 weeks 2
- In type 2 diabetes trials, degludec achieved HbA1c of 7.3% versus 7.3% with glargine U-100 at 52 weeks 2
Hypoglycemia Risk
- Degludec demonstrates lower rates of nocturnal hypoglycemia compared to glargine across multiple trials 3, 6
- In type 1 diabetes, nocturnal confirmed hypoglycemia was 25% lower with degludec (P=0.021) 6
- In type 2 diabetes, overall confirmed hypoglycemia was 18% lower and nocturnal hypoglycemia was 25% lower with degludec 6
Dosing Flexibility
- Degludec's ultra-long duration allows flexible once-daily dosing at varying times each day without compromising glycemic control or safety 3, 7
- Glargine requires administration at a consistent time each day to maintain stable blood glucose levels 5
Formulation Differences
Available Concentrations
- Degludec: Available in U-100 and U-200 formulations 1
- Glargine: Available in U-100 (Lantus) and U-300 (Toujeo) formulations 5, 1
Unique Properties
- Degludec can be mixed with rapid-acting insulin (coformulated as insulin degludec/insulin aspart), unlike glargine which cannot be diluted or mixed with any other insulin 5, 3
Cost-Effectiveness Considerations
- Insulin degludec is probably of low value compared to insulin glargine when added to usual care, with an estimated cost of $406,000 per QALY gained when used as basal insulin only, and $192,000 when used as basal-plus-bolus therapy 8
- The cost-effectiveness differences are driven largely by hypoglycemic event models, though severe hypoglycemia was rare in trials 8
Practical Switching Considerations
- When switching between these insulins, doses can often be converted unit-for-unit, but an initial dose reduction of 10-20% may be needed for patients at high risk of hypoglycemia 1
- Both insulins can be used in combination with mealtime insulin in type 1 diabetes or with oral medications in type 2 diabetes 1
Clinical Selection Guidance
Choose Degludec When:
- Patients experience recurrent nocturnal hypoglycemia on glargine 6
- Patients have unpredictable social or work schedules requiring flexible dosing timing 7
- Patients who travel frequently or find rigid scheduling a barrier to adherence 7
Choose Glargine When:
- Cost is a primary concern and hypoglycemia risk is acceptable 8
- Patients are achieving target glycemic control without hypoglycemia on current glargine therapy 5
Critical Caveats
- When basal insulin doses exceed 0.5 units/kg/day with A1C remaining above target, consider adding GLP-1 receptor agonists or prandial insulin rather than continuing to escalate either degludec or glargine 8, 5
- Both insulins provide similar glycemic control; the primary clinical advantage of degludec is reduced nocturnal hypoglycemia and dosing flexibility, not superior glucose lowering 3, 6