SUMMARY Twenty four men with insulin dependent diabetes and different degrees of autonomic neuropathy were studied to establish the response of the QT interval to various heart rates. Nine men with autonomic neuropathy had a longer QT interval than 13 healthy individuals and 15 patients who had diabetes without, or with only mild, autonomic neuropathy. Those with autono.mic neuropathy also had a proportionally greater lengthening of the QT interval for a given increase in RR interval.The results of this study suggest a basis for the finding that sudden death is more common in patients with diabetic autonomic neuropathy.An association between an abnormal QT interval and sudden cardiac death has been found in various diseases.'2 The influence of autonomic tone on the QT period is also widely accepted, although the mechanisms underlying the shortening or lengthening of this period are still not clear."4In the late 1970s several reports noted the high incidence of sudden death in diabetic patients who had severe autonomc neuropathy."6 In some cases death was attributed to cardiorespiratory arrest, but in the overwhelming majority the cause of death was not identified.This prompted us to investigate changes in QT interval during static (quiet lying, sitting, and standing) and dynamic (Valsalva manoeuvre) conditions in groups of diabetic patients with different degrees of autonomic neuropathy. Patients and methodsThe diabetic patients (men aged (mean (SD)) 42 (12)

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people think has been going on in recent months." The vagueness of this information and Minerva's earlier allegations does not help us. If the BMJ or its readers have any firm evidence which would enable investigations to be made the medicines division of the DHSS would, as I have said, still be glad to have it so that matters can be properly looked into.

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Coughing induces cardioacceleratory responses under cholinergic control. The Cough Test (CT), a standardized test that uses a series of coughs with electrocardiographic monitoring, was used to assess the functional integrity of cardiovascular autonomic nerves. In 224 control subjects and 235 diabetic patients, heart-rate (HR) responses were compared with four established tests: lying to standing (LS), standing to lying (SL), deep breathing (DB), and Valsalva maneuver (VM). In control subjects, HR responses declined significantly with age in a curvilinear pattern. Log-transformed indices were used to estimate percentiles. The CT-HR responses were reproducible and significantly associated with other HR-response tests. Sixty-nine (29%) diabetic patients had an abnormal value less than or equal to 1st percentile, whereas only 2 control subjects had such an abnormality. Among diabetic patients, age and duration of diabetes exerted a significant negative influence. With the use of the criteria of two abnormal or one abnormal and two borderline tests (among CT, LS, SL, DB, or VM) as a minimal criteria for cardiovascular autonomic neuropathy, CT and LS had the least overlap between the control and diabetic populations and were significantly better than SL or VM (P less than 0.005 for CT, P less than 0.01 for LS). They were not different from DB. We found the CT to be simple to perform, reproducible, and useful for the assessment of cardiovascular autonomic reflexes.