The rationale of homeopathic treatment of diabetes mellitus (DM) with constitutional predisposition is discussed. On the basis of a detailed analysis of one case the author describes the method of homeopathic treatment of diabetes mellitus. The treatment is orientated not only on the treatment of DM but also of concomitant diseases with emphasis in the patients constitution. Minimal doses of homeopathic treatment used in 68 patients resulted in a statistically valid stable reduction of hyperglycemia and glucosuria. Stable subcompensation and compensation of DM allowed to decrease the dose of sugar reducing drugs.