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

Abstract

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30 years ago for Mexican Americans with type 2 diabetes and since used with diverse samples in many countries, contains outdated items that no longer accurately assess current knowledge needed for diabetes self-management.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.