Dark-adapted Pupil Area and R-R Interval Variation in Diabetes Mellitus

Abstract

The relationship between pupil area in darkness (PA) and abnormality on R-R interval variation was studied in 45 patients with diabetes mellitus. The patients were divided into four groups according to the grade of somatic neuropathy. Group I consisted of patients clinically diagnosed as latent diabetes. Group II, III and IV consisted of diabetics without, with mild and with severe somatic neuropathy, respectively. PA was measured in complete darkness by infrared video-pupillography, and each was compared individually with sex-and age-matched controls. Mean PA was normal in Group I, but was significantly smaller in Groups II, III and IV. The degree of miosis (decrease in PA) correlated with the grade of somatic neuropathy. Mean coefficient of variation of R-R intervals on ECG during deep breathing (CV) showed no significant difference between controls and Groups I, II and III, but was decreased in Group IV. Although mean PA in patients with abnormal CV was smaller than in those with normal CV, there was no correlation between PA and CV. It is concluded that measurement of PA is a more sensitive and useful technique for detecting autonomic dysfunction in diabetes mellitus.