Decline in Neurophysiological Function After 7 Years in an Adolescent Diabetic Cohort and the Role of Aldose Reductase Gene Polymorphisms

Abstract
OBJECTIVE—This 7-year longitudinal study examines the potential impact of aldose reductase gene (AKR1B1) polymorphisms on the decline of nerve function in an adolescent diabetic cohort. RESEARCH DESIGN AND METHODS—Patients with type 1 diabetes (n = 262) were assessed with three cardiovascular autonomic tests (heart rate variation during deep breathing, Valsalva maneuver, and during standing from a lying position) and pupillometry (resting pupil diameter, constriction velocity, and reflex amplitude), thermal, and vibration thresholds on the foot. Genotyping was performed for promoters (C-106T and C-12G), (CA)n dinucleotide repeats, and intragenic BamH1 polymorphism. RESULTS—Median time between first and last assessment was 7.0 years (interquartile range 5.1–11.1), with a median of five assessments (four to seven) per individual. At first assessment, median age was 12.7 years (11.7–13.9), median duration was 5.3 years (3.4–8.0), and median HbA1c was 8.5% (7.8–9.3). All tests declined over time except for two cardiovascular autonomic tests and vibration discrimination. Faster decline in maximum constriction velocity was found to associate with the Z-2 allele (P = 0.045), Z-2/Z-2 (P = 0.026). Slower decline in hot thermal threshold discrimination associated with Z+2 (P = 0.044), Z+2/Z+2 (P < 0.0005), Z+2/T (P = 0.038), and bb (P = 0.0001). CONCLUSIONS—Most autonomic and quantitative sensory nerve testings declined over time. AKR1B1 polymorphisms were strongly associated with the rate of decline of these complications.

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