A new inhaled form of insulin, Afrezza, has been approved for use by the Food and Drug Administration (FDA). Whereas insulin taken by injection is a liquid, the inhaled insulin Afrezza is a powder. When inhaled, the powder is able to reach the bloodstream via the small blood vessels in the lungs quicker than insulin injections which go into subcutaneous tissue (the layer of fat just underneath the skin).

This means that, in addition to not requiring injections, the insulin acts ultra-rapidly, peaking in action between 15-20 minutes after inhalation and culminating its activity within an hour. The insulin is therefore able to avoid the sharp spikes one hour after eating that typically result from having carbohydrate based meals. The insulin is available to adults with type 1 and type 2 diabetes.

The news will be warmly welcomed by people with diabetes that struggle with taking regular insulin injections. It should be noted, however, that long term basal insulin will still need to be taken by injection. Doses of the insulin powder are contained in a cartridge which is put into the inhaler, called the Dreamboat. Cartridges are available in either 4 unit doses or a larger 8 unit dose. If you would usually take a 5 unit injection of rapid acting insulin, you would instead inhale 8 units of Afrezza. Whilst this may suggest that a hypo could occur, clinical trials showed that very low blood sugar levels were less common in Afrezza users than those that injected at meal times. Doses of over 8 units would involve using the inhaler twice for a single dose. For example taking 10 units would involve inhaling from an 8 unit cartridge and then inhaling from a 4 unit cartridge.

The manufacturers state that each Dreamboat inhaler needs to discarded after 15 days of use and replaced with a new inhaler. Clinical trials showed the inhaled insulin is effective at reducing HbA1, albeit not as effective in type 1 diabetes as NovoRapid, a common rapid acting injectable insulin. Side effects of Afrezza include risks of throat irritation, throat pain and possible hypoglycemia. The treatment is not recommended for anyone with breathing difficulties such as asthma or chronic obstructive pulmonary disease (COPD) or for anyone who smokes. Whilst Afrezza showed no significant risk of lung cancer to date, the FDA will review postmarketing studies to confirm.