The aim of this retrospective study was to verify whether the daily number of insulin injections could have affected metabolic control in 181 unselected diabetic patients (age 0.66-14.75 yr at onset of diabetes) followed in our clinic from the 1970s to the 1990s. They were evaluated regularly since onset of disease for a mean follow-up period of 6.8 years. The factor with the greatest effect on HbA1c levels was the year of disease onset, which was negatively correlated with HbA1c independently of the daily number of injections and disease duration. Disease duration showed an effect on metabolic control only in the first 5 years of disease. Daily insulin injections affected metabolic control above all as regards 1 vs 2 or more injections. Regarding the change in insulin regimen from 2 to 3-4 injections, there was an improvement in metabolic control in patients with HbA1c > 9% and a worsening in those with HbA1c < 7%/ After the first 5 years of the disease HbA1c levels were higher in adolescent patients than in both younger and older patients. In conclusion, increasing the daily number of injections does not seem in itself capable of eliciting marked improvement in metabolic control, as in our young diabetic patients in the last decade. Multiple insulin injection therapy seems to be mostly indicated for patients with poor control and for adolescents.