Inhaled Insulin for Type 2 Diabetes: Solution or Distraction?

• Administration, inhalation
• Insulin
• Diabetes mellitus, non-insulin-dependent
• Hemoglobin A, glycosylated
• Blood glucose

The second most famous “shot heard”—or felt—“round the world” was a 5-mL injection of pancreatic extract given to Leonard Thompson, a 13-year-old patient dying of diabetes, on 23 January 1922 (1). The extract had been prepared by Dr. J.B. Collip on the basis of the seminal work by Banting and Best (2). The insulin, as it came to be called, was relatively dilute—Thompson received 45 mL in the next 36 hours—and caused sterile abscesses. It was administered by using a glass-barreled syringe and probably a 21-gauge needle. Because the only insulin available in those early years was relatively short acting, three to four injections daily were necessary to control glycemia in the asymptomatic range.

During the ensuing 78 years, a wide array of highly purified insulins was developed, including recombinant human insulin, synthetic analogues, and numerous formulations providing a spectrum of action profiles. When combined with techniques for self-monitoring of blood glucose levels and the insights necessary to provide a physiologic supply of insulin and obtain near-normal glycemic control (3), modern insulin therapy can largely prevent or delay the progression of complications and improve the long-term prospects of persons with type 1 or type 2 diabetes mellitus (4, 5). The one constant of insulin therapy has been subcutaneous injections. Innovations in injection therapy, such as insulin pens and disposable syringes with ultra-fine 29-gauge needles, have made therapy more convenient and relatively painless; yet for patients …