Insulin glargine [rDNA origin] injection (Lantus®) was developed to provide a stable basal insulin replacement having a sustained effect over 24 hours. However, an urgent safety alert concerning overdosing with the injector used with Lantus® (OptiPen® Pro 1) has been issued, and the injector is difficult to use, which often causes problems. To investigate the problems in instructing patients on the use of this new type of insulin and its acceptance by them, we studied 62 diabetic patients (M/F= 23/39, 45 ± 14 yrs) who changed from NPH insulin to insulin glargine under intensified insulin therapy. We gave them a questionnaire to fill out and reviewed their charts. Some patients said that while the scale of the injector was large enough to see clearly, it did not return to 0 after injection. Others complained about its portability, and difficulties in replacing cartridges. However, patients also made favorable comments saying that the insulin glargine had reduced the number of injections necessary and frequency of hypoglycemic attacks, which improved their quality of life.