Development and Psychometric Assessment of a Manufacturer Independent Knowledge Questionnaire on Real Time Continuous Glucose Monitoring for insulin-treated People with Diabetes

Abstract

Abstract Background To benefit from real-time continuous glucose monitoring (rtCGM), users need practical skills and in-depth knowledge to analyze the glucose data appropriately and adapt insulin therapy accordingly. To assess the user’s knowledge about rtCGM, a psychometric knowledge test was developed and evaluated. Method Experts on the use of rtCGM systems defined central knowledge contents in a Delphi process and developed a knowledge test comprising 40 multiple-choice items. For test-statistical review, people with insulin-treated diabetes and members of diabetes teams answered the knowledge test. Results The 122 diabetes team members (age 46 (11) years; mean (SD)) and the 111 people with insulin-treated diabetes (age 42 (14) years, diabetes duration 20 (14) years, users of insulin pumps 64 %, previous usage of rtCGM 38 %, HbA1c 8.0 % [95 % CI 7.7–8.3] (64 mmol/mol [60–67]) had different levels of experiences using rtCGM systems. The internal consistency (Cronbach’s alpha) of the knowledge test was 0.92 for the whole sample, for people with diabetes 0.94, and for diabetes team members 0.84. Item difficulty ranged between 0.12 and 0.88 in people with diabetes and between 0.27 and 0.97 among diabetes team members. On average, people with diabetes answered 24.1 (9.9) items correctly, diabetes team members 29.2 (5.2) (p < 0.001); people with diabetes and previous rtCGM-experience had a higher knowledge compared to people without previous experience (29.2 (6.2) vs. 21.0 (10.4) (p = 0.001)). The quality of glucose control (measured by HbA1c) of the people with diabetes was significantly associated with the sum-score of the questionnaire (rho = –0.48, p < 0.001). Conclusion The “rtCGM-Profi-Check” knowledge test provides high internal consistency, high selectivity, and content validity. It is suitable for objective, reliable, and valid assessment of the indispensable knowledge of people with diabetes to use different rtCGM systems successfully. The questionnaire is manufacturer-independent and is suitable to evaluate the needs and success of rtCGM education among persons with diabetes.