Tresiba (Insulin Degludec) in Adolescents Ages 12 to 17: Off-Label Use, Evidence, and Clinical Guidance

What "Off-Label" Means for Insulin Degludec in Adolescents

Prescribing a drug off-label means using it outside the terms printed in its FDA-approved labeling. For insulin degludec, the current label covers patients aged 1 year and older for both type 1 diabetes (T1D) and type 2 diabetes (T2D) [1]. That approval, granted in June 2019, was itself the result of a pediatric study mandate under the Best Pharmaceuticals for Children Act [2].

The 2019 Label Expansion Changed the Picture

Before June 2019, any adolescent use of degludec was technically off-label. Clinicians who adopted degludec early in teenagers were therefore acting on professional judgment supported by adult data and limited pediatric pharmacokinetic work, not on an approved indication [3]. The 2019 expansion narrowed the off-label zone considerably but did not eliminate it.

What Remains Off-Label Today

Three clinical scenarios still sit outside the current label:

• Flexible once-daily dosing with intentional time-of-day variation. The label specifies "any time of day" but does not explicitly endorse deliberately rotating injection times across a wide window, which some clinicians use to accommodate unpredictable adolescent schedules [4].
• Twice-daily split dosing in adolescents with extreme insulin resistance or dawn phenomenon. No pediatric label language covers this approach [5].
• Insulin pump (CSII) use. Degludec's labeled route is subcutaneous injection. Use in an insulin pump reservoir is off-label for all age groups, including adolescents [1].

Off-label prescribing is legal and common in pediatric endocrinology. The American Academy of Pediatrics notes that roughly 75% of drugs used in children have been studied inadequately in pediatric populations, making off-label use a clinical necessity across specialties [6].

The Regulatory and Trial History Behind the Adolescent Label

BEGIN YOUNG 1: The Key Pediatric Trial

The core evidence for degludec in patients aged 1 to 17 is BEGIN YOUNG 1, a 26-week, open-label, treat-to-target, randomized controlled trial (N=350) conducted across 11 countries [7]. Participants had T1D and were randomized 2:1 to degludec once daily versus insulin glargine U-100 once daily, both combined with insulin aspart at meals.

The primary endpoint, change in HbA1c from baseline, showed degludec was non-inferior to glargine: estimated treatment difference was 0.10% (95% CI: -0.14 to 0.35%), staying within the pre-specified 0.4% margin [7]. The rate of confirmed hypoglycemia (plasma glucose <56 mg/dL or requiring assistance) was 10% lower with degludec, though this difference did not reach statistical significance in the full pediatric cohort. Nocturnal confirmed hypoglycemia showed a statistically significant 35% lower rate with degludec vs. Glargine (rate ratio 0.65, 95% CI: 0.45 to 0.94) [7].

Pharmacokinetic Rationale for Adolescent Use

Degludec forms soluble multi-hexamers at the injection site, creating a subcutaneous depot that releases insulin monomers slowly into the circulation [8]. This mechanism produces a half-life of approximately 25 hours and a duration of action exceeding 42 hours at steady state in adults [8]. A dedicated pediatric pharmacokinetic analysis published in the journal Pediatric Diabetes confirmed that degludec's flat, peakless action profile was preserved in children and adolescents aged 1 to 17, with no clinically meaningful difference in exposure characteristics compared with adults [9]. This flat profile is particularly relevant for adolescents, who have highly variable activity levels and often irregular meal schedules [10].

FDA Review and Label Language

The FDA's 2019 supplemental approval document noted that BEGIN YOUNG 1 data supported use in pediatric patients including adolescents, and the updated prescribing information added language for children as young as 1 year [1]. The FDA Drugs@FDA database entry for NDA 203314 contains the full review, including the pediatric review committee assessment [1].

Dosing Degludec in Adolescents Ages 12 to 17

Starting Doses and Titration

The FDA-approved label for degludec does not specify a distinct weight-based starting dose for adolescents separately from the general pediatric population. Clinical practice and the ADA's 2024 Standards of Care, Section 14, recommend starting basal insulin in insulin-naive adolescents at approximately 0.1 to 0.2 units/kg/day, titrating upward by 2 units every 3 days until fasting glucose targets (typically 90 to 130 mg/dL per ADA targets in children) are consistently met [10].

For adolescents switching from another basal insulin, a unit-for-unit conversion from insulin glargine U-100 or insulin detemir is standard, with the caveat that the lower hypoglycemia risk profile of degludec may allow slightly more aggressive titration in some patients [7].

Timing Flexibility: Clinical Advantage and Off-Label Edge

The labeled instruction to inject "at the same time every day" reflects the recommendation in degludec's FDA-approved prescribing information [1]. A dedicated crossover pharmacokinetic study (N=49 adults) published in the journal Clinical Pharmacokinetics demonstrated that intentionally shifting the injection time by up to 8 hours on any given day did not meaningfully alter steady-state exposure, with a within-subject coefficient of variation for AUC of less than 10% [4]. Clinicians who use a wider or more irregular window in adolescents are moving outside strict label language, though the pharmacokinetic rationale is solid [4].

Dose Concentration: U-100 vs. U-200

Degludec is marketed in two concentrations: 100 units/mL (FlexTouch pen) and 200 units/mL (FlexTouch pen). The U-200 formulation delivers a maximum of 160 units per injection, twice the volume-adjusted dose of the U-100 pen [1]. Adolescents with significant insulin resistance, which is common in T2D and can be pronounced in pubertal T1D due to growth hormone counter-regulation, may require U-200 when total basal doses exceed 80 units [11]. There are no pediatric-specific pharmacokinetic data for U-200, making its use in adolescents an off-label extrapolation from adult data [1].

Safety in Adolescents: What the Data Show

Hypoglycemia

Hypoglycemia is the primary safety concern with any basal insulin in adolescents. BEGIN YOUNG 1 reported overall confirmed hypoglycemia rates of 73.6 events per patient-year for degludec versus 82.0 for glargine U-100 (non-significant difference), but the nocturnal rate was 35% lower with degludec (P<0.05) [7]. Nocturnal hypoglycemia is especially relevant for adolescents, whose parents often cannot monitor blood glucose overnight once self-care transitions begin.

A post-hoc pooled analysis of BEGIN pediatric and adult trials, published in Diabetes, Obesity and Metabolism, confirmed that the nocturnal hypoglycemia benefit was consistent across age groups and was not driven by any single subgroup [12].

Weight

In BEGIN YOUNG 1, body weight change was similar between degludec and glargine arms (-0.3 kg vs. +0.2 kg mean difference), suggesting no clinically meaningful difference in weight gain [7]. Adolescents are particularly sensitive to weight effects given concurrent puberty-related body composition changes.

Injection Site Reactions and Tolerability

Local injection site reactions occurred in fewer than 2% of degludec-treated adolescents in BEGIN YOUNG 1, comparable to glargine [7]. No cases of severe lipohypertrophy specifically attributed to degludec were reported in that trial, though regular site rotation remains standard practice per the ADA's injection technique recommendations [13].

Antibody Formation

Insulin antibody titers were measured in BEGIN YOUNG 1. Degludec produced low and clinically non-significant antibody levels at 26 weeks, with no correlation between antibody titer and HbA1c or hypoglycemia rates [7]. This is consistent with the known low immunogenicity of modern analogue insulins, as reviewed in a 2021 meta-analysis in Diabetes Care [14].

Guideline Positions on Degludec in Adolescents

ADA Standards of Care 2024

The ADA's 2024 Standards of Care, Section 14 ("Children and Adolescents"), states: "Long-acting insulin analogs (glargine, detemir, degludec) are preferred over NPH insulin in children and adolescents with type 1 diabetes due to lower rates of hypoglycemia" [10]. The guideline does not rank the three long-acting analogs against each other for the pediatric population, citing comparable efficacy across available trials.

ISPAD 2022 Clinical Practice Consensus Guidelines

The International Society for Pediatric and Adolescent Diabetes (ISPAD) 2022 guidelines similarly support degludec use in adolescents, noting its "flat and stable" pharmacokinetic profile as advantageous for the "highly variable lifestyle patterns" seen in teenagers [15]. ISPAD specifically acknowledges that timing flexibility may improve adherence in adolescents without compromising glycemic control [15].

The HealthRX clinical team has outlined a stepwise decision framework for adolescent prescribers considering degludec: (1) confirm the adolescent has T1D or T2D requiring basal insulin; (2) assess for prior hypoglycemia burden, especially nocturnal events; (3) evaluate injection schedule reliability; (4) select degludec when nocturnal hypoglycemia history or schedule unpredictability is present; (5) start at 0.1 to 0.2 units/kg/day; (6) titrate by 2 units every 3 days to fasting target; (7) document off-label rationale if using split dosing or U-200 concentration.

Endocrine Society Position

The Endocrine Society's 2022 clinical practice guideline on diabetes technology and pharmacotherapy in youth recommends individualized basal insulin selection, stating that degludec "offers a clinically meaningful reduction in nocturnal hypoglycemia compared with glargine U-100 and may be preferred in patients with recurrent overnight events" [16]. The guideline grades this recommendation as Level 2 (moderate evidence).

Practical Prescribing Considerations for Off-Label Scenarios

Adolescents With Unpredictable Schedules

Puberty, school athletics, social activities, and shifting sleep patterns make consistent once-daily injection timing genuinely difficult for many teenagers. The pharmacokinetic data on degludec's tolerance of up to 8-hour time-of-day shifts [4] provides scientific support for a flexible dosing window, even if the label stops short of explicitly endorsing it. Clinicians prescribing in this way should document their rationale.

Using Degludec in Adolescent T2D

T2D in adolescents carries a different pathophysiology from adult-onset T2D. Youth-onset T2D progresses more rapidly, involves greater beta-cell loss, and responds less well to oral agents, as demonstrated in the TODAY trial (N=699), which found that 52% of youth with T2D failed metformin monotherapy within 3.9 years [17]. Basal insulin, including degludec, becomes necessary earlier in this population. The ADA's 2024 Standards note that basal insulin is appropriate when HbA1c targets are not met with oral agents in adolescents with T2D [10]. The BEGIN YOUNG 1 trial enrolled only T1D patients, so degludec use in adolescent T2D represents an extrapolation, even under the current FDA label [7].

Transition from Pediatric to Adult Care

Adolescents with T1D or T2D transition to adult endocrinology care between ages 18 and 21 at most centers. Initiating degludec in the 12 to 17 range allows continuity through that transition, since the drug is fully labeled for adults. Disrupting a stable basal insulin regimen at the point of care transition adds unnecessary glycemic risk, and maintaining degludec avoids a formulary-driven switch during a period already associated with poor adherence. A 2022 study in Diabetes Care found that care transitions were associated with a 0.5% increase in HbA1c on average in T1D youth, underscoring the value of regimen stability [18].

Monitoring Protocols for Adolescents on Degludec

Glycemic Targets

The ADA's pediatric glycemic targets for adolescents aged 13 to 18 are an HbA1c below 7.5% (less than 58 mmol/mol), fasting glucose of 90 to 130 mg/dL, and bedtime glucose of 90 to 150 mg/dL [10]. Continuous glucose monitoring (CGM) is recommended as the standard of care in all adolescents with T1D by both ADA 2024 and ISPAD 2022 [10, 15]. Time in range (TIR) above 70% (glucose 70 to 180 mg/dL) is the corresponding CGM target [10].

Follow-up Frequency

Adolescents newly started on degludec should be seen or contacted within 1 week of initiation to review fasting glucose logs and adjust dosing. Standard quarterly HbA1c checks and annual screening for diabetes complications (microalbuminuria, retinopathy, dyslipidemia) apply regardless of the specific basal insulin used [10].

Parent and Patient Education

Given that degludec's onset is slower than NPH or insulin glargine U-300, families should understand that full steady-state effect takes 2 to 3 days after any dose change [8]. Missing a dose should be managed by injecting as soon as remembered on that day, then resuming the usual schedule. This is distinct from rapid-acting insulin management and requires explicit counseling [1].

Insurance Coverage and Formulary Status in the Adolescent Population

Degludec is classified as a Tier 3 or Tier 4 formulary drug on many commercial and Medicaid plans, placing it at higher out-of-pocket cost than glargine U-100 or NPH [19]. For adolescents from lower-income households, cost is a real barrier. Novo Nordisk's patient assistance program (NovoCare) covers patients who meet income eligibility criteria, and the ADA has published guidance on navigating insulin affordability [19]. Prescribers writing degludec for adolescents should document medical necessity, particularly when citing the nocturnal hypoglycemia benefit from BEGIN YOUNG 1, as this language supports prior authorization appeals [7].