Self-efficacy in children with diabetes mellitus: testing of a measurement instrument.

The study reported here assessed the psychometric properties of an instrument to measure diabetes management self-efficacy in Dutch children, ages 8 to 12. Content validity of the item list was tested by consulting an expert panel of diabetes nurse specialists and a child-oriented rating scale was developed. A pretest was conducted to assess whether the instrument was clear and comprehensible for children. Then the instrument was tested in children with diabetes at the outpatient diabetes clinics for children at three Dutch hospitals. Reliability and criterion-related validity of the instrument were assessed. The instrument was judged content valid by the expert panel of diabetes nurse specialists, and the language of the instructions, the items and the rating scale was found to be clear and understandable for children of this age group. The study yielded only a moderate internal consistency estimate (Cronbach's = 0.71) and limited support for criterion-related validity. Several useful theoretical and methodological issues were identified.