Effect of actual glycaemia on pupillary function in children with type 1 diabetes

The objective was to study the effect of actual glycaemia on autonomic function. Autonomic function was assessed by computerised infrared video-pupillometry in 10 children with type 1 diabetes (age 10.5-15.8, median 13.7 years, diabetes duration 1.1-10.0, median 3.8 years) on 6 occasions (07:30, 12:00, 17:30 h on days 1 and 10, respectively). Blood glucose was measured by a reflectance meter immediately prior to each pupillometry study. To allow for inter-individual differences in pupillary variables (resting pupil diameter (RPD), reflex amplitude (RA), maximum constriction velocity (MCV)) the variation of each variable from the mean for the individual (difference between the actual value and the mean value from the 6 measurements (delta RPD, delta RA, delta MCV)) was used in calculations. None of the three pupillary variables showed a significant correlation with the blood glucose value (delta RPD: r = 0.072, P = 0.59; delta RA: r = -0.008, P = 0.96; delta MCV: r = -0.080, P = 0.55). It is concluded, that autonomic function in children with Type 1 diabetes as determined by computerised infrared video-pupillometry is not affected by actual glycaemia.