Poorly controlled diabetes mellitus results in structural and functional changes in many brain regions. We demonstrate that in streptozotocin-induced diabetic rats cell death is increased and proliferation decreased in the cerebellum, indicating overall cell loss. Levels of both the proform and cleaved forms of caspases 3, 6 and 9 are increased, with no change in caspases 7, 8 or 12. Colocalization of glial fibrillary acidic protein (GFAP) and cleaved caspase 3 and GFAP in TUNEL-positive cells increased in diabetic rats. Changes in GFAP levels paralleled modifications in proliferating cell nuclear antigen (PCNA), increasing at 1 week of diabetes and decreasing thereafter, and proliferating GFAP-positive cells were decreased in the cerebellum of diabetic rats. These results suggest that astrocytes are dramatically affected in the cerebellum, including an increase in cell death and a decrease in proliferation, and this could play a role in the structural and functional changes in this brain area in diabetes.