A STRUCTURAL EQUATION MODEL FOR PREDICTORS OF SEVERE HYPOGLYCEMIA IN PATIENTS WITH INSULIN-DEPENDENT DIABETES-MELLITUS

There are several predictors of severe hypoglycaemia in patients with insulin-dependent diabetes mellitus (IDDM), many of which are correlat ed. To assess factors which may be predictive of severe hypoglycaemia, structural equation modelling was used to test specific hypotheses us ing prospective data. Sixty patients with insulin-dependent diabetes m ellitus (IDDM) were studied prospectively for one year during which an y episodes of severe hypoglycaemia, asymptomatic biochemical hypoglyca emia, and glycaemic control were documented. Half the patients reporte d hypoglycaemia unawareness and they were matched for HbA(1) with the rest. Baseline measurements included symptomatic awareness of hypoglyc aemia, fear of hypoglycaemia, previous history of hypoglycaemia, glyca emic control, and peripheral autonomic function. Formal structural equ ation modelling was performed on these variables and a model was const ructed that expressed the putative causal associations among the varia bles. The frequency of severe hypoglycaemia (measured prospectively) c orrelated significantly with duration of diabetes, awareness of hypogl ycaemia, patient's age, history of previous severe hypoglycaemia and a utonomic function scores. HbA(1) did not show significant correlation, possibly because of the narrow range in the subject population. In th e structural equation modelling exercise, at least 18 % of the varianc e of severe hypoglycaemia, measured prospectively, was accounted for b y a history of severe hypoglycaemia, the state of awareness of hypogly caemia, and the autonomic function score. Over 25 % of the variance of 'worry' on the hypoglycaemia fear scale was accounted for by a histor y of previous severe hypoglycaemia. An assessment of multiple risk fac tors for hypoglycaemia may be of value in advising individual patients about their diabetes care.