We thank Berger et al. (1) for raising questions about the serious issue of reusing insulin syringes and pen needles. The source of the photographs used by Becton Dickinson is an independent study conducted in 1997 by Dr. Jacques Garden, Chairman of the Department of Metallurgy at the University of Grenoble, France (unpublished observation).
In Garden’s study, 80 diabetic patients from the Diabetes Service of Dr. Dieter Look returned their used pen needles and indicated the number of times each specific needle had been used. All needles were used in a customary fashion and spanned the range of manufacturer types, gauges, and needle lengths. Needles were used from 2 to 38 times. Needle tips were then resterilized for safety reasons and examined by electron microscopy (2).
The tip damage found by Garden ranged from mild bending of the extreme tip to a hook-like distortion of the entire distal shaft of the needle. Loss of the tip was seen on one occasion. Some needles appeared undamaged, even after many reuses. (In this regard Garden’s findings agree with those of Berger et al.) However, a clear association was seen between the severity of tip damage and the number of needle reuses.
Among the needles, some looked just like the ones provided by Berger et al. Some were much worse than the ones we have chosen to show the public. We are unsure why the results of Berger et al. differ from our own. Among the possible causes are 1) the magnification used was at least an order of magnitude less than that of Garden (>300×), 2) the health care professionals in their study may be more careful than patients when performing injections or may use different techniques, or 3) they viewed fewer samples, and sampling error may have resulted. We would welcome a full discussion of this study with Berger et al.
We advise against pen needle and insulin syringe reuse for a number of reasons. First, the syringes may become hooked, as we have previously described. The “hook” at the tip of the syringe may break off and become lodged in the skin, and the pain of injection with a syringe increases with each reuse.
Second, studies conducted by a series of nurses in Europe have shown significant increases in lipodystrophy in patients who reuse insulin syringes and pen needles (3). Third, there are reports of increased infections from reuse of insulin syringes (4). Finally, reusing syringes can lead to suboptimal therapy. With syringes, the patient can bring significant amounts of NPH into the regular or lispro vial. With pens, leaving the needle on between uses can lead to incomplete injections, which may cause the patient to underdose themselves and receive as little as 35% of the expected dose (5).
We believe the issue of insulin syringe and pen needle reuse to be serious, with real safety concerns that have not been fully explored in the past. We welcome a more complete scientific discussion of this issue.
