Design and validation of a scale to assess preferences of type 2 diabetic patients towards different nutritional supplements.

OBJECTIVES To design and validate a scale to evaluate preferences of type 2 diabetic patients towards nutritional supplements (Madrid scale) and to discover those taste attributes that are more discriminating. CONTEXT ambulatory patients with type 2 diabetes mellitus. MATERIALS AND METHODS 18 controls and 106 type 2 diabetic patients received 2 of the 7 stimuli studied (6 nutritional supplements and a differential salty stimulus) and then completed both scales and a criterion question. Two weeks later, 30 diabetic patients received a retest. The psychometric properties of the Madrid scale were studied and the relative importance of each stimuli attribute was assessed. RESULTS Feasibility: The Madrid scale consists of 8 questions and is completed in less than five minutes; Dimensionality: A single dimension which explains 45.1% of the variance. Reliability: Cronbach's , 0.806; intraclass correlation coefficient, 0.835 (95% confidence interval: 0.653-0.922). Concurrent validity: Correlation indexes of the corrected total score with the criterion question and the Modified Wine-Tasting Scale, 0.731 (p < 0.0005) and 0.774 (p < 0.0005), respectively. The scale discriminated between subjects younger and older than 75 years and between supplements and the differential stimulus. Preferences: Glucerna SR chocolate, Glucerna SR strawberry, Glucerna SR vanilla, Diasip vanilla, Clinutren vanilla and Resource diabet vanilla. CONCLUSION The Madrid scale has adequate psychometric properties for its use in research and daily clinical practice.