With domestication and urbanisation, cats have transformed from being hunting animals that eat protein-rich prey into more sedentary animals that eat a carbohydrate-rich diet. It was hypothesised that a high intake of dry cat food and a lack of physical activity may play a role in the development of feline type 2 diabetes mellitus. Information on dietary history and physical activity of 96 cats with diabetes mellitus and 192 matched controls was collected retrospectively, using a telephone questionnaire. Conditional logistic regression analysis was used to investigate the association between questionnaire-derived variables and the development of diabetes mellitus. The energy percentage of dry food in the diet was not significantly correlated with the development of diabetes mellitus (P=0.29), whereas both indoor confinement (P=0.002) and low physical activity (P=0.004) were. The results indicated that the proportion of dry food in a cat's diet may not be an independent risk factor for the development of type 2 diabetes mellitus, whereas physical inactivity and indoor confinement are.