Summary. Five different methods of analysing R-R interval (heart rate) variation were compared, using a computer technique, in 61 diabetics with a wide range of responses to autonomic function testing. Two methods differentiated best between the diabetics with and without autonomic damage: (1) the standard deviation of the mean R-R interval recorded for 5 min during quiet breathing with the subject either sitting or standing; (2) the difference between the maximum and minimum heart rates recorded over 1 min during deep breathing at six breaths per minute, again with the subject either sitting or standing. For routine clinical usage we conclude that recording the heart rate for 1 min on an ECG, while the subject sits and breaths deeply at six breaths per minute, and then measuring the difference between the maximum and minimum heart rate, is the most practical method currently available. For research purposes either this method or the standard deviation method during quiet breathing for 5 min, should be used.Key words: Diabetes mellitus, autonomic neuropathy, R-R interval variation, tests of autonomic function Beat-to-beat (R-R interval) variation in heart rate has been recognised for many years, but it was only in 1973 that its use as a measure of the integrity of the autonomic nervous system was first described [1]. Wheeler and Watkins [1] showed that beat-to-beat heart rate variation during deep breathing, measured with a heart rate monitor, was diminished in some diabetics and attributed this to vagal neuropathy since atropine, but not propranolol, abolished the

A study was made of the distribution of primary thyroid failure, indicated by a raised serum TSH concentration, in 605 (294 males and 311 females) insulin-dependent (type I) diabetics, aged 21-84 yr, not previously suspected of having thyroid disease. The prevalence of a raised serum TSH concentration in females of all ages (17%) was significantly greater (P less than 0.0005) than that in males (6.1%) and increased with increasing age at onset of diabetes (P less than 0.05) and age at time of study (P less than 0.001) in females but not in males. There was no significant difference in the duration of diabetes when comparing patients with normal and raised serum TSH concentrations. The prevalence of a raised TSH concentration in late-onset insulin-dependent diabetics was no greater in patients requiring insulin within 3 months of diagnosis of diabetes than in those exhibiting secondary sulfonylurea failure, who required insulin more than 3 months after diagnosis. In type I diabetes, the prevalence of subclinical primary thyroid failure is considerably greater than has previously been suspected, with female late-onset insulin-dependent diabetics being at the greatest risk.

A two-stage screening strategy was used to study psychiatric morbidity and social problems in a consecutive series of out-patients with insulin-dependent diabetes mellitus. The prevalence of psychiatric morbidity was 18%, and consisted of depression, anxiety, and attendant symptoms. Patients reporting major social problems had significantly higher levels of psychiatric symptoms. Psychiatric morbidity was not associated with the presence of complications of diabetes.

SUMMARY Plasma ,8-thromboglobulin, platelet factor 4, fibrinogen, fibrinopeptide A, antithrombin III, factor VIII related antigen, a2-macroglobulin, platelet count, and total glycosylated haemoglobin were measured in three well matched groups of subjects: non-diabetic controls, diabetics without retinopathy, and diabetics with proliferative retinopathy. /8-thromboglobulin and platelet factor 4 concentrations were significantly higher in the diabetics with retinopathy than in the controls and platelet factor 4 was also increased in the diabetics without retinopathy compared with controls. Fibrinogen concentration was raised in diabetics without retinopathy compared with controls, diabetics with retinopathy compared with controls, and diabetics with retinopathy compared with those without. Fibrinopeptide A concentration did not differ significantly between groups. Antithrombin III levels were increased in diabetics with retinopathy compared with controls, and in diabetics with retinopathy compared with those without. Factor VIII related antigen values were higher in both the diabetic groups when compared with the controls. Fibrinopeptide A concentration correlated with both /8-thromboglobulin and platelet factor 4 in each of the three groups.Haemostatic abnormalities in diabetes have been shown, although a hypercoagulable state has not been confirmed. These changes in platelet and coagulation function may be secondary to the development of microvascular disease and their role in the pathogenesis of retinopathy remains uncertain.Patients with diabetes mellitus have significantly increased morbidity and mortality as a consequence of specific microvascular disease, which results in conditions such as retinopathy and nephropathy. Although the precise cause of these vascular complications remains uncertain, evidence is accumulating that an imbalance of the haemostatic mechanisms may be entailed in their initiation or propagation.