The reliability of an item designed to measure health belief is often confounded with response consistency at the person level. The study applied contemporary measurement methods to an inventory of common sense beliefs about diabetes and used a sample of N = 563 adults with diabetes to test the hypothesis that individuals whose beliefs are congruent with a biomedical model are more consistent in their responses. Item-level analysis revealed that the domains of Causes and Medical Management were the least reliable. Person-level analysis showed that respondents who held views congruent with the biomedical model were more consistent than people who did not.