Revision and Psychometric Evaluation of the Diabetes Knowledge Questionnaire for People With Type 2 Diabetes.

Objective: Diabetes knowledge is associated with health, including lower A1C levels. The Diabetes Knowledge Questionnaire (DKQ-24), developed 30 years ago for Mexican Americans with type 2 diabetes and since used with diverse samples in many countries, contains outdated items that no longer accurately assess current knowledge needed for diabetes self-management. We revised the DKQ-24 and tested psychometric properties of the DKQ-Revised (DKQ-R) with a diverse sample.

Methods: We conducted a five-phase instrumentation study as follows: 1) DKQ-24 items were revised to reflect current diabetes care standards; 2) the Delphi method was used to evaluate the DKQ-R's content validity (n = 5 experts); 3) cognitive interviews were conducted with people with type 2 diabetes (n = 5) to assess their interpretations of DKQ-R items; 4) cross-sectional administration of the DKQ-R to adults with type 2 diabetes was carried out to assess internal consistency reliability and convergent validity; and 5) an item analysis was conducted using discrimination index and point biserial analysis.

Results: After receiving the experts' feedback and conducting the cognitive interviews, 39 items were administered to 258 participants with type 2 diabetes (42.2% women; 29.1% Latino, 42.6% Asian, mean age 55.7 years). To select the final items, we considered the item discrimination index, as well as item-to-total correlations, content area, and participant feedback. The final 22-item DKQ-R uses the same yes/no/I don't know response format as the DKQ-24. The DKQ-R is strongly correlated with the DKQ-24 (r = 0.71, P <0.01) and is weakly correlated with diabetes numeracy (r = 0.23, P <0.01), indicating adequate convergent validity; a Kuder-Richardson-20 coefficient of 0.77 indicated good reliability.

Conclusion: The DKQ-R is a reliable and valid updated measure of diabetes knowledge for diverse populations with type 2 diabetes.