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Diabetes Management Advances in Insulin Injection Research Influences Patient Adherence Ronnie Aronson, MD, 1 Timothy Bailey, MD, 2 Laurence Hirsch, MD 3 and Rita Saltiel-Berzin, RN, MPH, CDE 3 1. Executive Director, LMC Endocrinology Centres, Toronto, Ontario, Canada; 2. Director, AMCR Institute, Inc., Escondido, California, US; 3. BD (Becton Dickinson and Company), Franklin Lakes, New Jersey, US Abstract Insulin formulations and injection devices have improved dramatically since the first insulin injection was given in 1922. Adherence to insulin therapy, however, is estimated at 62–64 % despite research indicating that good glycemic control improves patient outcomes. The challenge is to improve the rates of adherence and to intensify or progress insulin therapy as needed. Changes in insulin delivery devices, especially innovations in needle technology in combination with education and support, have the potential to improve the comfort of insulin injections and encourage patients to adhere to their insulin regimens. Keywords Insulin pen needles, adherence to insulin therapy, psychological insulin resistance, skin thickness Disclosure: Ronnie Aronson, MD, has received honoraria and research grants from Becton Dickinson (BD), as well as from Eli Lilly, Novo Nordisk, and Sanofi. Timothy Bailey, MD, has been a consultant for Bayer, BD, Lifescan, Medtronic, Novo Nordisk, Roche, and Sanofi, has received speaking honoraria from Novo Nordisk, and has received research support from Abbott, Animas, Bayer, BD, Boehringer Ingelheim, Cebix, Bristol Myers Squibb, Dexcom, GlaxoSmithKline, Halozyme, Insulet, Lifescan, Lilly, Mannkind, Medtronic, Merck, Novo Nordisk, Orexigen, Resmed, Sanofi, Tandem, and Versartis. Laurence Hirsch, MD, and Rita Saltiel-Berzin, RN, MPH, CDE, are employees of BD. Received: October 4, 2013 Accepted: November 11, 2013 Citation: US Endocrinology, 2013;9(2):114–8 Correspondence: Ronnie Aronson, MD, LMC Diabetes & Endocrinology, Suite 106, 1929 Bayview Avenue, Toronto, ON, Canada M4G 3E8. E: ronnie.aronson@lmc.ca Support: The publication of this article was supported by Becton Dickinson. The views and opinions expressed are those of the authors and not necessarily those of Becton Dickinson. The emergence of new formulations of insulin and injectable medications has made insulin therapy safer and more effective. Evolution has stimulated innovations in insulin delivery systems that, in turn, may positively affect patient comfort and adherence to insulin therapy. This article will review the progress made in understanding skin and subcutaneous (SC) fat thickness at injection sites, its implications for the design of an optimal needle for injecting insulin, and the potential impact on patient adherence. Background The first insulin injection was given in 1922 to Leonard Thompson, a 14- year-old boy in Canada, who was near death from type 1 diabetes. The injection was given with a glass hypodermic syringe and bare steel needle. Insulin was heralded as a lifesaving drug and its founders were awarded the Nobel Prize, in 1923. 1 The first insulin syringe specifically manufactured for insulin therapy became available in 1924 and included a 25-gauge (G) needle. Syringes and needles were boiled to sterilize them before use. Needles were sharpened with a whetstone, which most people associate with the sharpening of knives. This process continued until 1961, when the first disposable plastic insulin syringe was introduced, the forerunner of today’s syringe with an integrated or staked needle. 2 Insulin pen use began in the 1980s as an alternative to insulin vials and syringes. Shaped like a fountain pen, they contain a cartridge of insulin and require a dual-ended pen needle, attached separately before the injection. Patients simply dial a dose of insulin and push a button to 114 deliver the desired amount. This development allowed insulin injections to be given in a more convenient and simple manner. To provide a historical perspective to the evolution of changes in needle length and gauge (diameter), one only has to compare the sizes of insulin needles over the years (see Figure 1). In 1985, insulin was given in a syringe with a 27G, 16  mm needle. Today, insulin syringes are available with needles as short and thin as 6  mm, 31G, or via insulin pen with needles as small as 4 mm, 32G. A 32G needle has an external diameter of approximately 0.23–0.24 mm, or 0.009 inch (ISO Standard 9626)—not much different from a human eyelash. Studies have consistently shown that glycemic control is equivalent, regardless of needle size used, and that patients preferred the shorter, finer-gauge (smaller diameter) needles, reporting less pain, and generally no difference in backflow or insulin leakage from the skin. 3–11 Recently, needle tip bevels have been ground to become even sharper and flatter, penetrating the skin with less force, leading to a more comfortable injection. 12 Recently, the cannula wall has been made thinner (while preserving the external dimensions), making a larger inner diameter of the needle and requiring less force to push the button on the pen that delivers insulin (and/or less time to dispense the dose). 13 Although not visible to the user, these technological advances make injections more comfortable and easier to administer. They have helped patients © TOU C H ME D ICA L ME D IA 2013