Study 171 was an open-label study involving 518 patients with type 1 diabetes on basal/bolus insulin therapy who were studied at sites in the United States, Russia, Ukraine and Brazil. After a four-week run-in period to optimize their basal insulin, patients entered a 24-week treatment period in which they were randomized in one of three ways:
- Continuing on subcutaneous insulin aspart in combination with a basal insulin (170 patients);
- Switching to AFREZZA administered using the Gen2 inhaler in combination with their basal insulin (174 patients); or
- Switching to AFREZZA administered using the MedTone inhaler in combination with their basal insulin (174 patients).
The treatment period consisted of 12 weeks of prandial insulin optimization with continued basal titration followed by a 12-week period during which subjects maintained stable doses of insulin (prandial and basal). There was also a follow-up visit four weeks after completion of the treatment period.
Over the 24-week treatment period of this study, A1c levels decreased comparably in the AFREZZA-Gen2 group (-0.21%) and the insulin aspart group (-0.40%). The 95% confidence interval (0.02% to 0.36%) of the between-group difference did not exceed the predetermined threshold of 0.40%, thereby establishing non-inferiority between AFREZZA-Gen2 and insulin aspart, which was the primary endpoint of the study.Other Results There was a significant difference in fasting blood glucose (FBG) levels in the AFREZZA-Gen2 group compared to the insulin aspart group. In the AFREZZA-Gen2 group, mean FBG levels decreased by 25.3 mg/dL by the end of the treatment period whereas the insulin aspart group experienced an increase of 10.2 mg/dL in FBG levels over the same period (p=0.0027). After the four-week follow-up period, during which all patients received insulin aspart and a basal insulin, there was no longer any difference in FBG levels between the treatment groups, demonstrating that this effect on FBG levels was attributable to AFREZZA therapy. Significantly less total hypoglycemia was observed in the AFREZZA-Gen2 group (9.80 events per subject-month) compared to the insulin aspart group (13.97 events per subject-month; p<0.0001). The event rate of severe hypoglycemia was also lower in the AFREZZA-Gen2 group (8.05 events per 100 subject-months) than in the insulin aspart group (14.45 events per 100 subject-months); however, this difference was not statistically significant (p=0.1022).