At a geriatric department 61 insulin-dependent diabetics have been treated with des-phe-insulin (DPI) for periods of up to 6 years since 1976. The use of either pure DPI, amorphous DPI or DPI mixed with varying amounts of crystalline non-modified insulin of the same species allowed flexible longterm therapy, as well as management of metabolic emergencies. Comparison of the doses needed before and after change to and from other insulin preparations showed no difference in efficacy. No side effects of such severity as to necessitate interruption of therapy were observed.