Three years after an FDA rejection over an inhaler switch-up, California-based MannKind said Phase III data show its inhaled insulin helped people with diabetes control their disease. Preliminary results, announced Wednesday, showed that the powder, administered via the 2.0 version of its inhaler, called Dreamboat, was more effective at lowering A1c levels among type 2 diabetics when used with oral therapy than oral therapy alone.

The 24-week study included 353 type-2 diabetes patients whose condition was inadequately controlled on metformin with or without additional orals. The study found that, among patients taking a pill along with MannKind’s Afrezza, mean A1c levels fell .82%, compared to .42% among those taking orals alone. In addition 37.7% of those in the Afrezza + oral group hit A1c levels below 7%, compared to the non-Afrezza group, of which 19% hit the A1c benchmark.

When the company approached the FDA in 2010, the inhaler it used in the trials was not the one it wanted to continue with. FDA boomeranged the filing, saying it wanted updated safety data that was based on Afrezza and the intended inhaler. The regulator did not cite any safety issues with the drug, Bloomberg News reported at the time.

The inhaled formulation’s appeal is ease of use, but key opinion leaders at a Leerink Swann July roundtable did not consider convenience enough of a reason to back the drug. Experts told Leerink analysts that there could be safety concerns with inhaled insulin.

Pfizer’s now-defunct Exubera, for instance, was associated with scattered cases of cancer in clinical trials. Exubera also suffered from poor sales – Pfizer returned rights to then-partner Nektar Therapeutics in 2007. Novo also pursued in inhaled treatment, but abandoned its late-stage testing in 2008, as did Eli Lilly.