Structural equation modeling of symptoms, awareness and fear of hypoglycemia, and personality in patients with insulin-treated diabetes.

OBJECTIVE

To assess the possible influence of personality on self-reported awareness, symptoms, and fear of hypoglycemia and also to identify the relationship among these self-reported measures using formal structural equation modeling.

RESEARCH DESIGN AND METHODS

A structured questionnaire, which included questions about sociodemographic details, awareness of the onset of hypoglycemia, and a list of symptoms of hypoglycemia, was completed by 305 consecutive insulin-treated diabetic patients attending the diabetic clinic at the Royal Infirmary of Edinburgh. They also completed the Hypoglycemia Fear Survey (HFS), and personality was assessed using the short form of the shortened Eysenck Personality Questionnaire-Revised (EPQ-R). Formal structural equation modeling was performed using the following variables: awareness, autonomic symptoms, neuroglycopenic symptoms, severe hypoglycemic episodes in the last year, worry and behavior (from the HFS), and extroversion and neuroticism (from the short EPQ-R). This allowed a model to be constructed that expressed the putative causal associations among the variables that could be tested statistically.

RESULTS

Of the 302 patients who had experienced hypoglycemia, 111 (37%) reported reduced awareness, and these patients scored higher on the worry subscale of the HFS (reduced awareness: 41 +/- 12 vs. normal awareness: 34 +/- 12, P < 0.001). The patients with reduced awareness scored higher for neuroticism than did the patients with normal awareness (reduced awareness: 6.1 +/- 3.4 vs. normal awareness: 4.9 +/- 3.3, P < 0.01) and scored lower for extroversion (reduced awareness: 5.8 +/- 3.7 vs. normal awareness: 7.1 +/- 3.7, P < 0.01). In the structural equation modeling exercise, neuroticism was a significant putative determinant of many of the other variables.

CONCLUSIONS

Personality was the major determinant of the variance that could be accounted for in this study and influenced self-reported symptoms, awareness, and fear of hypoglycemia. Personality factors may, therefore, influence self-reports from patients, particularly when soft measures, such as symptoms, are assessed and even when using validated clinical questionnaires. This finding stresses the importance of using additional evidence, such as reports from relatives, to substantiate reports from patients of loss of hypoglycemia awareness.