To deplore the relationship between leptin and c-peptide in children with type 1 diabetic mellitus (DM). The levels of serum leptin and c-peptide(C-P) in 65 type 1 DM children (including 31 before and after insulin treatment) and 30 normal controls were measured by radioimmunoassay (RIA). The results found that there was significant differences ( P <0.01) in leptin and C-P between DM children and normal controls

also in 31 DM children before and after treatment. It showed a positive correlation between leptin and C-P. The changes of the leptin/C-P ratio in DM children compared with normal controls and that before and after treatment were also significantly different. It suggested that leptin may have close relationship in the development

progress and the occurrence of complications in children with DM and also provide a new clue for their diagnosis treatment and complication occurrence.