IS AUTONOMIC NEUROPATHY A RISK FACTOR FOR SEVERE HYPOGLYCEMIA - THE EURODIAB IDDM COMPLICATIONS STUDY

The hypothesis that diabetic patients with autonomic neuropathy are at increased risk of severe hypoglycaemia was examined in an epidemiolog ical study of over 3000 IDDM patients in Europe (EURODIAB IDDM Complic ations Study). Autonomic function was assessed by two standard cardiov ascular tests: change in heart rate and systolic blood pressure on sta nding. Severe hypoglycaemia was defined as an attack serious enough to require the help of another person, Compared to patients (68 %) repor ting no attacks in the last year, those reporting one or more attacks were older (34.0 +/- 10.7 vs 32.1 +/- 9.9 years, mean +/- SD, p < 0.00 01), had had diabetes for a longer period (14.6 +/- 9.5 vs 13.8 +/- 9. 1 years, p < 0.0001), had better glycaemic control (HbA(1c) 6.4 +/- 1. 8 vs 6.9 +/- 1.9 %, p < 0.0001) and were more likely (p = 0.002) to ha ve abnormal responses to both autonomic tests (13.0 vs 7.7 %). A singl e abnormal autonomic response was not associated with an increased ris k of severe hypoglycaemia. The odds ratio for severe hypoglycaemia in people with abnormal responses to both autonomic tests, compared to th ose will normal responses, was 1.7 (95 % confidence interval 1.3, 2.2) after controlling for age, duration of diabetes, glycaemic control an d study centre. In conclusion: a combined autonomic deficit in heart r ate and blood pressure responses to standing is associated with only a modest increase in the risk of se were spontaneous hypoglycaemia. Alt hough the increase in risk is not large, severe hypoglycaemia was a fr equently reported event in this study. IDDM patients with deficient au tonomic responses who strive for tight glycaemic control map therefore be at particular risk of severe hypoglycaemia.