Abstract: Objective To provide the evidence for health education of elderly diabetes mellitus（DM） patients by investigating their use of insulin pens outside of hospital. Methods Use of insulin pens in 60 DM patients discharged from hospital after they were treated from January 2011 to June 2011 was investigated using questionnaire we designed.The credibility of Cronbach’sαcoefficient was 0.89 and the content validity was 0.94 obtained from the returned questionnaires.The results were described by rate. Results Only 20% patients washed their hands before insulin injection,36.11% patients chose iodine preparation as their disinfectant,only 2.78% patients exhausted the air in injectors before injection,only 43.33% and 37.78% patients selected the injection sites 5cm around the umbilicus and avoid Cullen during insulin injection,40% patients injected insulin in a non-fist holding posture,no patient replaced the insulin pen needle after injection,only 21.11% patients pulled out the needle 6s after injection and pressed the injection button,only 13.33% put needles into the sharp box and discarded them at specified locations,only 25% patients stored the insulin pen in a dark place at room temperature,27.22% knew the expiry date of opened insulin pens. Conclusion The use of insulin pens in DM patients outside of hospital is not optimistic and it is thus necessary to strengthen health education for those who inject insulin themselves.