Background: Currently available short-acting insulin analogs have slower absorption compared with endogenous insulin occasionally resulting in immediate postprandial hyperglycemia. Intradermal (ID) injection facilitates faster drug absorption and may result in improved insulin pharmacokinetics.
Methods: Seventeen patients with type 2 diabetes were included in this single-center, pilot, open-label crossover study. Patients received 0.2 U/kg Insulin aspart ID injections using a MicronJet (MJ) needle and subcutaneous (SC) injections, using a conventional needle in a crossover design. Thirteen patients were studied under fasting conditions and four before a standard meal test. The pharmacokinetic/pharmacodynamic (PK/PD) profile, as well as the safety and tolerability of injections, was compared.
Results: Fourteen patients completed the study per-protocol. ID versus SC injection demonstrated significantly shorter Tmax (median 35 vs. 87.5 min [P < 0.001]), while the Cmax did not significantly differ (median 80 vs. 55 μU/mL [P = 0.085]). Median insulin area under the curve (AUC; 360 min) did not differ between the groups (9914 vs. 10,936 μU/mL/min [p = 0.077]), yet 0-60 min insulin AUC was higher with ID versus SC injection (mean ± SD 3821 ± 1429 vs. 2534 ± 737 μU/mL/min [p = 0.01]) and 4-6 h AUC was lower with ID versus SC injection (mean ± SD 2054 ± 858 vs. 2929 ± 1412 μU/mL/min [p = 0.02]). The relative bioavailability of the ID versus the SC insulin (AUCID/AUCSC) was similar (median 0.91 [95% confidence interval 0.73-1.27]).
Conclusions: ID insulin injection delivered through an MJ needle demonstrated superior PK profile compared with conventional SC administration, including shorter Tmax and higher early and lower late exposure in patients with type 2 diabetes. This may help achieve better insulin coverage of meals and lower postprandial glucose excursions.