Objective: To evaluate computerized infrared pupillometry for the assessment of autonomic neuropathy in adolescents with type I diabetes.
Research design and methods: We measured resting pupil diameters and pupillary light reflexes in 142 adolescents with type I diabetes (72 boys and 70 girls, 10.4-19.8 yr of age, duration of diabetes 0.7-18.3 yr) and in 75 nondiabetic control subjects (29 boys, 46 girls, 11.3-19.8 yr of age). All study participants were assessed using four standard cardiovascular tests: maximum-minimum heart rate during deep breathing (mean of three cycles); heart-rate change during a Valsalva maneuver (Valsalva ratio, mean of three maneuvers); lying-to-standing heart-rate change (30:15 ratio); and lying-to-standing BP change.
Results: Mean resting pupil diameters were significantly smaller in the diabetic group: 6.28 +/- 0.06 vs. 6.77 +/- 0.11 mm, P < 0.0001); and significantly smaller with greater duration of diabetes (r = -0.29, P = 0.0006) and higher levels of GHb (r = -0.24, P = 0.004). Patients with retinopathy grade 30 or more (Wisconsin 191 grading) had significantly smaller resting pupil diameters: 5.9 +/- 0.16 vs. 6.4 +/- 0.12 mm, P = 0.008). The phasic light reflex as determined by reflex amplitude and maximum constriction velocity was significantly reduced in the diabetic group: 2.27 +/- 0.03 vs. 2.44 +/- 0.04 mm, P = 0.0009; and 6.68 +/- 0.12 vs. 7.24 +/- 0.16 mm/s, P = 0.007). Reduced reflex amplitude was related to a longer postpubertal duration of diabetes (r = -0.18, P = 0.04). We found no association between pupillary and cardiovascular tests.
Conclusions: Infrared computerized pupillometry demonstrates subclinical diabetic autonomic neuropathy as early as adolescence. Its presence seems to be related to longer duration of diabetes and unfavorable metabolic control.