A comprehensive database has been maintained on patients attending the St. Paul's Hospital Diabetes Teaching and Treatment Centre (DTTC) since 1984. In November 1995, four sets of patients, all of whom had returned to the Centre, were identified for an outcome study. The sets were: insulin-dependent diabetes mellitus (IDDM), diet-treated non-insulin-dependent diabetes mellitus (NIDDM), oral agent-treated NIDDM, insulin-treated NIDDM. Data on glycosylated hemoglobin (A1c) values, percent ideal body weight (%IBW), home blood glucose monitoring (HBGM/week were analysed for all sets; data on hypoglycemic events/month were analysed only for the group with IDDM. Results demonstrated that patients in all groups performed significantly more HBGM over time. Downward change in %IBW in the diet-treated and oral agent groups was significant. Upward change in %IBW was significant in the IDDM group. Hypoglycemic events did not significantly increase in IDDM patients even though A1c improved. Most notably, the A1c values improved in all four groups up to 8 years after the first DTTC visit. Implications for practice are suggested.