Objective Uncomplicated, acute upper respiratory tract infections (URTIs) occur in patients with diabetes at a similar frequency to the general population. This study (NCT00642681) investigated the effect of URTIs on the pharmacokinetic (PK) and pharmacodynamic (PD) properties of Technosphere inhaled insulin (TI) in patients with type 1 or type 2 diabetes.

Research design and methods This was a phase 2 study conducted in patients who developed a URTI while being treated with TI in a phase 3 study (N=20, mean age 50 years, 60% men). Patients underwent two 4-hour meal challenges, during which blood samples were drawn to measure serum fumaryl diketopiperazine (FDKP; the excipient representing an essential part of TI), serum insulin, serum C-peptide, and plasma glucose. The primary outcome was the ratio of serum FDKP area under the concentration–time curve from 0 to 240 min (AUC_{0–240 min}) during URTI and after clinical resolution of URTI symptoms (≥15 to ≤45 days).

Results No significant differences in PK parameters were seen during URTI versus post-URTI for FDKP. The ratio of serum FDKP AUC_{0–240 min} during URTI and post-URTI was 1.1 (SD 0.6), p=0.4462. Plasma glucose concentrations during each 4-hour meal challenge were similar, showing small non-significant differences. No adverse events, including hypoglycemia, occurred during meal challenge visits.

Conclusions Development of an active, symptomatic URTI during treatment with TI had no significant impact on the PK/PD properties of TI, suggesting that no adjustment in prandial insulin dosing is needed. However, if patients are unable to conduct proper inhalation, they should administer their prandial insulin subcutaneously.

Trial registration number NCT00642681; Results.