Thiscrossover study compared the effect of fiber in dogs with induced diabetes mellitus. The study use 3 diets (high in insoluble fibre, high in soluble fibre and low in fibre).Six dogs were used, and they were randomly assigned to a predetermined diet sequence. Each dog was fed the diet during 56 days. All dogs were given pork lente insulin and half of their daily caloric intake at 12-hour intervals. Serum alkaline phosphatase activity was significantly higher in dogs with the low fibre diet compared to the other 2 diets. Mean postprandial plasma glucose concentration measured every 2 hours for 24 hours was significantly lower at most blood sampling times in dogs fed the high insoluble fibre diet and high soluble fibre diet, compared with dogs fed the low fibre diet.