Insulin syringes: dangers of dead space.

To assess the accuracy and reproducibility of various U100 insulin syringes in the hands of diabetics, we devised a method to measure individual insulins injected from the syringe. We found alarming inaccuracies with dead-space-containing syringes when two insulins were mixed in the syringe before injection; these errors exceeded 100% with low doses. Reproducibility of dose was also poor with dead-space syringes. Syringes with minimal dead space overcome these problems and we recommend that all diabetics who mix insulins should use these syringes.