In this study we evaluated 31 insulin-dependent diabetes mellitus (IDDM) patients (ages 12.1 +/- 3.4 years, 18 males/13 females) who started on multiple subcutaneous insulin injections (MSII) within six weeks of diagnosis and achieved either complete (CR: no insulin requirement and near-normoglycemia for at least two weeks) or incomplete (ICR: minimum 50% decline in insulin requirement while maintaining near-normoglycemia for two weeks or more) remissions within the first 12 weeks of the MSII trial. Methylprednisolone pulse therapy (MP) was administered four times per day by i.v. bolus at a dose of 30 mg/kg (max. 1000 mg) on alternative days. Eleven patients did not accept "MP-pulse" therapy; therefore, we followed these cases (7 males/4 females) as the control group. During the first year of follow-up, 13 patients from the "MP pulse" group achieved CR (3 males/1 female) or ICR (5 males/4 females) in 3.5 to 14 months. Remission occurred in only two of the control group cases (1 male CR for 17 days and 1 female CR for 7 months). Of those with CR in the "MP-pulse" and control groups, all were greater than 12 years of age, and all but one in the "MP-pulse" group were males. The stimulation capacity of beta cells (as defined by percentage increase in serum C-peptide levels after glucagon injection) among CR cases was found to be higher than that of non-remitted (NR) cases (p < 0.05 at onset, p < 0.001 during MSII-induced remission and p < 0.05 at the end of the first year of follow-up). Although patients with CR or ICR had higher beta cell reserves than NR cases at onset, only CR cases could sustain this capacity during the MSII-induced remission phase and one year after "MP-pulse" therapy. From this preliminary study, we conclude that "MP-pulse" therapy, may lead to prolonged near-normal beta cell function or partly preserved residual beta cell reserve during the MSII-induced remission phase of IDDM, The beneficial effects of MP could be seen clearly in patients diagnosed during the late childhood years.