The companies, along with Nektar Therapeutics, are seeking to market the drug, Exubera, as an alternative to injections many diabetics need to control their blood sugar levels.
The news is expected to delay the eventual launch of this drug, which has been hailed as a major advance in insulin delivery, promising to greatly enhance insulin compliance among diabetes sufferers, particularly those who currently require multiple daily insulin injections.
Pfizer and Sanofi-Aventis have a global agreement to co-develop, co-promote (where permitted by law), and co-manufacture inhaled insulin. Nektar, producers of Exubera are responsible for manufacturing the fine insulin powders and supplying the inhalers.
In September, an FDA Advisory Committee recommended approval of Exubera for the treatment of adults with type 1 and type 2 diabetes.
The FDA is not obligated to follow the Advisory Committee's recommendation, but usually does so.
Resounding to the latest developments, Pfizer and Sanofi-Aventis have said they will continue to work closely with the FDA so that this medicine can be made available for patients.
The additional data could have links over concerns about users' potential decreased lung capacity, which the manufacturing companies had promised to study further.
It is this reason that Exubera's path to market has been delayed for a number of years.
However, in clinical studies, patients experienced a small decrease in lung capacity in the initial weeks of treatment but the changes did not worsen during two years of study and were reversible if Exubera was stopped.
Exubera is a rapid-acting insulin preparation that is inhaled into the lungs prior to each meal, using a proprietary inhalation device and powdered insulin formulation developed by Nektar Therapeutics.
Exubera closely mimics the normal physiological insulin response to meals by quickly being absorbed into the bloodstream to reduce meal-related spikes in glucose levels in people with diabetes.
Diabetes is fast reaching epidemic proportions. An estimated 180 million people around the world suffer from diabetes and experts believe the number could reach 300 million within 20 years, as an obesity epidemic triggers more cases of type 2, or adult-onset, diabetes.
Approximately 22.5 million people suffer from diabetes in Europe alone, with type 2 diabetes accounting for 85-95 per cent of all diagnosed cases.