Diabetic bladder dysfunction is a common complication of diabetes mellitus (DM) with poorly understood natural history. This study examined the temporal changes in bladder function 3, 9, 12, and 20 wk after induction of DM by streptozotocin (STZ) in male C57BL/6 mice compared with that in age-matched diabetic mice treated with insulin, 5% sucrose-induced diuretic mice, and sham-treated control mice. Conscious cystometrograms of mice were examined in addition to the measurements of micturition cycle. Diabetes resulted in decreased body weight. Bladder weight, urine output, bladder capacity, and compliance increased in the DM and diuretic groups. Peak voiding pressure (PVP) increased initially in both DM and diuretic mice. However, in DM mice, PVP dropped dramatically at and after 12 wk. Similar changes in the capacity, compliance, and emptying ability of the bladder were seen during the first 9 wk of the diabetes or diuresis, whereas significant decline in the emptying ability of the bladder was only seen in diabetes after 12 wk of disease in mice. Long-term insulin replacement effectively reversed most changes in bladder function. These results suggest that the transition from a compensated to a decompensated bladder dysfunction occurs 9-12 wk after induction of DM in mice by STZ.