Pharmacotherapeutic group: Drugs used in diabetes, dipeptidyl peptidase 4 (DPP‑4) inhibitors, ATC code: A10BH05
Mechanism of action
Linagliptin is an inhibitor of the enzyme DPP‑4 (dipeptidyl peptidase 4, EC 3.4.14.5) an enzyme which is involved in the inactivation of the incretin hormones GLP‑1 and GIP (glucagon-like peptide‑1, glucose-dependent insulinotropic polypeptide). These hormones are rapidly degraded by the enzyme DPP‑4. Both incretin hormones are involved in the physiological regulation of glucose homeostasis. Incretins are secreted at a low basal level throughout the day and levels rise immediately after meal intake. GLP‑1 and GIP increase insulin biosynthesis and secretion from pancreatic beta cells in the presence of normal and elevated blood glucose levels. Furthermore GLP‑1 also reduces glucagon secretion from pancreatic alpha cells, resulting in a reduction in hepatic glucose output. Linagliptin binds very effectively to DPP‑4 in a reversible manner and thus leads to a sustained increase and a prolongation of active incretin levels. Linagliptin glucose-dependently increases insulin secretion and lowers glucagon secretion thus resulting in an overall improvement in the glucose homeostasis. Linagliptin binds selectively to DPP‑4 and exhibits a > 10 000 fold selectivity versus DPP‑8 or DPP‑9 activity in vitro.
Clinical efficacy and safety
8 phase III randomised controlled trials involving 5 239 patients with type 2 diabetes, of which 3 319 were treated with linagliptin were conducted to evaluate efficacy and safety. These studies had 929 patients of 65 years and over who were on linagliptin. There were also 1 238 patients with mild renal impairment, and 143 patients with moderate renal impairment on linagliptin. Linagliptin once daily produced clinically significant improvements in glycaemic control, with no clinically relevant change in body weight. The reductions in glycosylated haemoglobin A1c (HbA1c) were similar across different subgroups including gender, age, renal impairment and body mass index (BMI). Higher baseline HbA1c was associated with a greater reduction in HbA1c. There was a significant difference in reduction in HbA1c between Asian patients (0.8%) and White patients (0.5%) in the pooled studies.
Linagliptin as monotherapy in patients ineligible for metformin
The efficacy and safety of linagliptin monotherapy was evaluated in a double-blind placebo-controlled study of 24 weeks duration. Treatment with once daily linagliptin at 5 mg provided a significant improvement in HbA1c (‑0.69% change compared to placebo), in patients with baseline HbA1c of approximately 8%. Linagliptin also showed significant improvements in fasting plasma glucose (FPG), and 2‑hour post-prandial glucose (PPG) compared to placebo. The observed incidence of hypoglycaemia in patients treated with linagliptin was similar to placebo.
The efficacy and safety of linagliptin monotherapy was also evaluated in patients for whom metformin therapy is inappropriate, due to intolerability or contraindicated due to renal impairment, in a double-blind placebo-controlled study of 18 weeks duration. Linagliptin provided significant improvements in HbA1c, (‑0.57% change compared to placebo), from a mean baseline HbA1c of 8.09%. Linagliptin also showed significant improvements in fasting plasma glucose (FPG) compared to placebo. The observed incidence of hypoglycaemia in patients treated with linagliptin was similar to placebo.
Linagliptin as add-on to metformin therapy
The efficacy and safety of linagliptin in combination with metformin was evaluated in a double-blind placebo-controlled study of 24 weeks duration. Linagliptin provided significant improvements in HbA1c, (‑0.64% change compared to placebo), from a mean baseline HbA1c of 8%. Linagliptin also showed significant improvements in fasting plasma glucose (FPG), and 2‑hour post-prandial glucose (PPG) compared to placebo. The observed incidence of hypoglycaemia in patients treated with linagliptin was similar to placebo.
Linagliptin as add-on to a combination of metformin and sulphonylurea therapy
A placebo-controlled study of 24 weeks in duration was conducted to evaluate the efficacy and safety of linagliptin 5 mg to placebo, in patients not sufficiently treated with a combination with metformin and a sulphonylurea. Linagliptin provided significant improvements in HbA1c (‑0.62% change compared to placebo), from a mean baseline HbA1c of 8.14%. Linagliptin also showed significant improvements in patients fasting plasma glucose (FPG), and 2‑hour post-prandial glucose (PPG), compared to placebo.
Linagliptin as add-on to a combination of metformin and empagliflozin therapy
In patients inadequately controlled with metformin and empagliflozin (10 mg (n = 247) or 25 mg (n = 217)), 24‑weeks treatment with add-on therapy of linagliptin 5 mg provided adjusted mean HbA1c reductions from baseline by ‑0.53% (significant difference to add-on placebo ‑0.32% (95% CI ‑0.52, ‑0.13) and ‑0.58% (significant difference to add-on placebo ‑0.47% (95% CI ‑0.66; ‑0.28), respectively. A statistically significant greater proportion of patients with a baseline HbA1c ≥ 7.0% and treated with linagliptin 5 mg achieved a target HbA1c of < 7% compared to placebo.
Linagliptin as add-on to insulin therapy
The efficacy and safety of the addition of linagliptin 5 mg to insulin alone or in combination with metformin and/or pioglitazone has been evaluated in a double-blind placebo-controlled study of 24 weeks duration. Linagliptin provided significant improvements in HbA1c (‑0.65% compared to placebo) from a mean baseline HbA1c of 8.3%. Linagliptin also provided significant improvements in fasting plasma glucose (FPG), and a greater proportion of patients achieved a target HbA1c of < 7.0%, compared to placebo. This was achieved with a stable insulin dose (40.1 IU). Body weight did not differ significantly between the groups. Effects on plasma lipids were negligible. The observed incidence of hypoglycaemia in patients treated with linagliptin was similar to placebo (22.2% linagliptin; 21.2% placebo).
Linagliptin 24 month data, as add-on to metformin in comparison with glimepiride
In a study comparing the efficacy and safety of the addition of linagliptin 5 mg or glimepiride (mean dose 3 mg) in patients with inadequate glycaemic control on metformin monotherapy, mean reductions in HbA1c were ‑0.16% with linagliptin (mean baseline HbA1c 7.69%) and ‑0.36% with glimepiride (mean baseline HbA1c 7.69%.) with a mean treatment difference of 0.20% (97.5% CI: 0.09, 0.299). The incidence of hypoglycaemia in the linagliptin group (7.5%) was significantly lower than that in the glimepiride group (36.1%). Patients treated with linagliptin exhibited a significant mean decrease from baseline in body weight compared to a significant weight gain in patients administered glimepiride (‑1.39 vs +1.29 kg).
Linagliptin as add-on therapy in patients with severe renal impairment, 12 week placebo-controlled data (stable background) and 40 week placebo-controlled extension (adjustable background)
The efficacy and safety of linagliptin was also evaluated in type 2 diabetes patients with severe renal impairment in a double-blind study versus placebo for 12 weeks duration, during which background glycaemic therapies were kept stable. Most patients (80.5%) received insulin as background therapy, alone or in combination with other oral anti-diabetics such as sulphonylurea, glinide and pioglitazone. There was a further follow up 40 week treatment period during which dose adjustments in antidiabetes background therapies were allowed.
Linagliptin provided significant improvements in HbA1c (‑0.59 % change compared to placebo after 12 weeks), from a mean baseline HbA1c of 8.2%. The observed difference in HbA1c over placebo was ‑0.72% after 52 weeks.
Body weight did not differ significantly between the groups. The observed incidence of hypoglycaemia in patients treated with linagliptin was higher than placebo, due to an increase in asymptomatic hypoglycaemic events. There was no difference between groups in severe hypoglycaemic events.
Linagliptin as add-on therapy in elderly (age ≥ 70 years) with type 2 diabetes
The efficacy and safety of linagliptin in elderly (age ≥ 70 years) with type 2 diabetes was evaluated in a double-blind study of 24 weeks duration. Patients received metformin and/or sulphonylurea and/or insulin as background therapy. Doses of background antidiabetic medicinal products were kept stable during the first 12 weeks, after which adjustments were permitted. Linagliptin provided significant improvements in HbA1c (‑0.64 % change compared to placebo after 24 weeks), from a mean baseline HbA1c of 7.8%. Linagliptin also showed significant improvements in fasting plasma glucose (FPG) compared to placebo. Body weight did not differ significantly between the groups.
Linagliptin cardiovascular and renal safety study (CARMELINA)
CARMELINA was a randomized study in 6 979 patients with type 2 diabetes with increased CV risk evidenced by a history of established macrovascular or renal disease who were treated with linagliptin 5 mg (3 494) or placebo (3 485) added to standard of care targeting regional standards for HbA1c, CV risk factors and renal disease. The study population included 1 211 (17.4%) patients ≥ 75 years of age and 4 348 (62.3%) patients with renal impairment. Approximately 19% of the population had eGFR ≥ 45 to < 60 mL/min/1.73 m2, 28% of the population had eGFR ≥ 30 to < 45 mL/min/1.73 m2 and 15% had eGFR < 30 mL/min/1.73 m2. The mean HbA1c at baseline was 8.0%.
The study was designed to demonstrate non-inferiority for the primary cardiovascular endpoint which was a composite of the first occurrence of cardiovascular death or a non-fatal myocardial infarction (MI) or a non-fatal stroke (3P‑MACE). The renal composite endpoint was defined as renal death or sustained end stage renal disease or sustained decrease of 40% or more in eGFR.
After a median follow up of 2.2 years, linagliptin, when added to usual care, did not increase the risk of major adverse cardiovascular events or renal outcome events. There was no increased risk in hospitalization for heart failure which was an additional adjudicated endpoint observed compared to usual care without linagliptin in patients with type 2 diabetes (see table 2).
Table 2 Cardiovascular and renal outcomes by treatment group in the CARMELINA study
| | Linagliptin 5 mg | Placebo | Hazard Ratio |
| Number of Subjects (%) | Incidence Rate per 1 000 PY* | Number of Subjects (%) | Incidence Rate per 1 000 PY* | (95% CI) |
| Number of patients | 3 494 | | 3 485 | | |
| Primary CV composite (Cardiovascular death, non-fatal MI, non-fatal stroke) | 434 (12.4) | 57.7 | 420 (12.1) | 56.3 | 1.02 (0.89, 1.17)** |
| Secondary renal composite (renal death, ESRD, 40% sustained decrease in eGFR) | 327 (9.4) | 48.9 | 306 (8.8) | 46.6 | 1.04 (0.89, 1.22) |
| All-cause mortality | 367 (10.5) | 46.9 | 373 (10.7) | 48.0 | 0.98 (0.84, 1.13) |
| CV death | 255 (7.3) | 32.6 | 264 (7.6) | 34 | 0.96 (0.81, 1.14) |
| Hospitalization for heart failure | 209 (6.0) | 27.7 | 226 (6.5) | 30.4 | 0.90 (0.74, 1.08) |
* PY = patient years
** Test on non-inferiority to demonstrate that the upper bound of the 95% CI for the hazard ratio is less than 1.3
In analyses for albuminuria progression (change from normoalbuminuria to micro- or macroalbuminuria, or from microalbuminuria to macroalbuminuria) the estimated hazard ratio was 0.86 (95% CI 0.78, 0.95) for linagliptin versus placebo.
Linagliptin cardiovascular safety study (CAROLINA)
CAROLINA was a randomized study in 6 033 patients with early type 2 diabetes and increased CV risk or established complications who were treated with linagliptin 5 mg (3 023) or glimepiride 1‑4 mg (3 010) added to standard of care (including background therapy with metformin in 83% of patients) targeting regional standards for HbA1c and CV risk factors. The mean age for study population was 64 years and included 2 030 (34%) patients ≥ 70 years of age. The study population included 2 089 (35%) patients with cardiovascular disease and 1 130 (19%) patients with renal impairment with an eGFR < 60 mL/min/1.73 m2 at baseline. The mean HbA1c at baseline was 7.15%.
The study was designed to demonstrate non-inferiority for the primary cardiovascular endpoint which was a composite of the first occurrence of cardiovascular death or a non-fatal myocardial infarction (MI) or a non-fatal stroke (3P‑MACE).
After a median follow up of 6.25 years, linagliptin did not increase the risk of major adverse cardiovascular events (see table 3) as compared to glimepiride. Results were consistent for patients treated with or without metformin.
Table 3 Major adverse cardiovascular events (MACE) and mortality by treatment group in the CAROLINA study
| | Linagliptin 5 mg | Glimepiride (1‑4 mg) | Hazard Ratio |
| Number of Subjects (%) | Incidence Rate per 1 000 PY* | Number of Subjects (%) | Incidence Rate per 1 000 PY* | (95% CI) |
| Number of patients | 3 023 | 3 010 | |
| Primary CV composite (Cardiovascular death, non-fatal MI, non-fatal stroke) | 356 (11.8) | 20.7 | 362 (12.0) | 21.2 | 0.98 (0.84, 1.14)** |
| All-cause mortality | 308 (10.2) | 16.8 | 336 (11.2) | 18.4 | 0.91 (0.78, 1.06) |
| CV death | 169 (5.6) | 9.2 | 168 (5.6) | 9.2 | 1.00 (0.81, 1.24) |
| Hospitalization for heart failure (HHF) | 112 (3.7) | 6.4 | 92 (3.1) | 5.3 | 1.21 (0.92, 1.59) |
* PY = patient years
** Test on non-inferiority to demonstrate that the upper bound of the 95% CI for the hazard ratio is less than 1.3
For the entire treatment period (median time on treatment 5.9 years) the rate of patients with moderate or severe hypoglycaemia was 6.5% on linagliptin versus 30.9% on glimepiride, severe hypoglycaemia occurred in 0.3% of patients on linagliptin versus 2.2% on glimepiride.
Paediatric population
The clinical efficacy and safety of empagliflozin 10 mg with potential dose-increase to 25 mg or linagliptin 5 mg once daily has been studied in children and adolescents from 10 to 17 years of age with T2DM in a double-blind, randomised, placebo-controlled, parallel group study (DINAMO) over 26 weeks, with a double-blind active treatment safety extension period up to 52 weeks.
At baseline, the mean HbA1c was 8.03%. Treatment with linagliptin 5 mg did not provide significant improvement in HbA1c. The treatment difference of adjusted mean change in HbA1c after 26 weeks between linagliptin and placebo was ‑0.34% (95% CI ‑0.99, 0.30; p = 0.2935). The adjusted mean change in HbA1c from baseline was 0.33% in patients treated with linagliptin and 0.68% in patients treated with placebo (see section 4.2).