Insulin Degludec vs Glargine U-300
Insulin degludec (Tresiba) and insulin glargine U-300 (Toujeo) are ultra-long-acting basal insulin analogs designed to provide flat, stable pharmacodynamic profiles over 24+ hours. Degludec forms soluble multi-hexamer chains after subcutaneous injection, while glargine U-300 precipitates as amorphous microprecipitates that slowly dissolve. Both achieve >42-hour half-lives with once-daily dosing.
Structural and Mechanistic Differences
Section titled “Structural and Mechanistic Differences”Insulin Degludec
Section titled “Insulin Degludec”Insulin degludec is a hexamer-forming insulin analog. The B29 lysine is acylated with a C-16 fatty hexadecanedioic acid via a glutamic acid linker. After subcutaneous injection in the presence of zinc, degludec molecules self-associate into soluble multi-hexamer chains containing >6 zinc ions per hexamer. These chains slowly dissociate into monomers, which enter the circulation and bind albumin. The resulting pharmacokinetic profile has a half-life of >42 hours with peak-to-trough ratios of approximately 1.2:1.
The ultra-flat profile is attributed to the gradual, continuous release of monomers from the multi-hexamer depot.
Insulin Glargine U-300
Section titled “Insulin Glargine U-300”Insulin glargine is produced by recombinant DNA technology with two amino acid substitutions: Gly replaces Asn at position A21, and two Arg residues are added at the C-terminus of the B chain. These modifications shift the isoelectric point from pH 5.4 (native insulin) to pH 6.7, causing precipitation at physiological pH after subcutaneous injection.
Glargine U-300 is formulated at three times the concentration of U-100, reducing the injection volume by 67%. The smaller depot size slows dissolution, extending the half-life to approximately 36 hours and producing a flatter profile than glargine U-100.
Comparison Table
Section titled “Comparison Table”| Property | Insulin Degludec (U-100/U-200) | Insulin Glargine U-300 |
|---|---|---|
| MW (Da) | 9,541 | 6,064 |
| Mechanism | Multi-hexamer chain formation | Microprecipitate dissolution |
| Half-life | >42 hrs | ~36 hrs |
| Duration of action | >42 hrs | ~36 hrs |
| Peak-to-trough ratio | ~1.2:1 | ~1.5:1 |
| Dosing flexibility | ≥8 hrs (4 hrs for U-200) | Fixed 24-hr interval |
| Concentrations | U-100, U-200 | U-300 |
| Pen device | FlexTouch (red) | SoloStar (purple) |
Pharmacodynamic Profile
Section titled “Pharmacodynamic Profile”Clamp Studies
Section titled “Clamp Studies”Euglycemic clamp studies provide the most direct comparison of pharmacodynamic profiles:
| Parameter | Degludec | Glargine U-300 |
|---|---|---|
| Onset | 30–90 min | 2–5 hrs |
| Peak | Flat | Flat |
| Duration | >42 hrs | ~36 hrs |
| Total GIR AUC | 100% | 93–97% |
| Day-to-day variability | 20% lower | Baseline |
| Nocturnal hypoglycemia | 36% lower | Baseline |
GIR = Glucose infusion rate. Lower AUC with glargine U-300 indicates slightly lower total glucose-lowering effect, but the difference is clinically marginal.
Steady-State Behavior
Section titled “Steady-State Behavior”Degludec achieves true steady state after 3–4 days of once-daily dosing, with no accumulation beyond day 3. Glargine U-300 achieves steady state within 2–3 days. The ultra-flat degludec profile means that the time of injection has minimal impact on glucose control, supporting flexible dosing.
Clinical Evidence
Section titled “Clinical Evidence”DEVOTE (Degludec vs Glargine U-100)
Section titled “DEVOTE (Degludec vs Glargine U-100)”The DEVOTE trial (n=7,637) compared degludec to glargine U-100 in high cardiovascular risk T2D patients:
- Primary endpoint (MACE): HR 0.91 (95% CI 0.78–1.06); non-inferior
- Severe hypoglycemia: 40% reduction with degludec (HR 0.60; 95% CI 0.48–0.76)
- Nocturnal severe hypoglycemia: 53% reduction (HR 0.47; 95% CI 0.31–0.73)
- Duration: 2 years
CONCLUDE (Degludec vs Glargine U-300)
Section titled “CONCLUDE (Degludec vs Glargine U-300)”The CONCLUDE trial (n=1,649) directly compared degludec to glargine U-300:
- Primary endpoint (day-to-day variability in SMBG): Degludec superior (ratio 0.89; 95% CI 0.81–0.98)
- Nocturnal confirmed hypoglycemia: 30% lower with degludec
- Severe hypoglycemia: No significant difference
- Duration: 1 year
BRIGHT (Glargine U-300 vs Degludec)
Section titled “BRIGHT (Glargine U-300 vs Degludec)”- Primary endpoint (symptomatic hypoglycemia): Non-inferior
- Overall hypoglycemia: Similar rates
- Nocturnal hypoglycemia: Similar rates
Hypoglycemia Risk
Section titled “Hypoglycemia Risk”| Hypoglycemia Type | Degludec | Glargine U-300 |
|---|---|---|
| Overall (any) | Lower | Baseline |
| Nocturnal | 30–53% lower | Baseline |
| Severe | 40% lower | Baseline |
| Symptomatic | Similar | Similar |
The hypoglycemia advantage of degludec is most pronounced at night and during glycemic variability. The flat pharmacokinetic profile reduces mismatch between insulin action and glucose disposal.
Dosing Flexibility
Section titled “Dosing Flexibility”| Feature | Degludec | Glargine U-300 |
|---|---|---|
| Minimum dosing interval | 8 hrs (U-100), 4 hrs (U-200) | 24 hrs |
| Missed dose window | 8–40 hrs | Not recommended |
| Flexible timing | Yes | Fixed |
| Dose splitting | Allowed | Not studied |
Degludec’s ultra-long half-life enables truly flexible dosing without loss of glycemic control or increased hypoglycemia risk. This is particularly valuable for patients with irregular schedules or shift workers.
Cost and Access
Section titled “Cost and Access”| Factor | Degludec | Glargine U-300 |
|---|---|---|
| Brand name | Tresiba | Toujeo |
| List price (monthly) | ~$500–600 | ~$450–550 |
| Insurance coverage | Broadly covered | Broadly covered |
| Pen device | FlexTouch (300 U) | SoloStar (450 U) |
| Cartridge | Penfill (3 mL) | Single-use pen |
Both agents are priced comparably. Glargine U-300 may have slight cost advantages depending on insurance formulary placement.
When to Choose Which
Section titled “When to Choose Which”Insulin degludec may be preferred when:
- Flexible dosing schedule is needed
- Nocturnal hypoglycemia is a concern
- Maximum reduction in severe hypoglycemia is desired
- Shift work or irregular schedules
- History of hypoglycemia unawareness
Insulin glargine U-300 may be preferred when:
- Established regimen with Toujeo
- Cost or formulary favors glargine U-300
- Fixed daily routine is acceptable
- Smaller injection volume is preferred
References
Section titled “References”- Marso SP, et al. “Insulin degludec versus glargine in patients with type 2 diabetes (DEVOTE).” NEJM 2017;377:723-732.
- Philis-Tsimikas A, et al. “Degludec versus glargine U-300 in type 2 diabetes (CONCLUDE).” Diabetes Obes Metab 2019;21:1292-1300.
- Rosenstock J, et al. “Randomized comparison of glargine U-300 and degludec in type 2 diabetes (BRIGHT).” Diabetes Care 2018;41:2487-2494.
- Heise T, et al. “Ultra-long-acting insulin degludec has a flat action profile.” Diabetes Obes Metab 2012;14:859-864.
- Lucidi P, et al. “Pharmacokinetics/pharmacodynamics of glargine U-300.” Diabetes Obes Metab 2015;17:265-273.