Aims: To identify factors that represent relationships among sets of interrelated thermal and vibration threshold variables and to find clinical correlates that are significantly associated with these factors.
Methods: Thermal and vibration perception thresholds were tested in the hands and feet of Type 1 diabetic patients treated in an outpatient clinic for juvenile-onset diabetes. Factor analysis was used to identify factors that represent relationships among sets of thermal and vibration threshold variables.
Results: One hundred and forty-eight patients (47.3% males, median current age 22.3 years and median duration of diabetes 11.4 years) were evaluated. Three factors explained 77% of the total variance: 'hand sensation' factor, underlying cold, warmth and vibration perception thresholds in the hand; 'foot sensation' factor, underlying the same sensory thresholds in the foot; and 'heat-related pain' factor, underlying heat pain perception threshold in both limbs. The 'foot sensation' factor was the only factor that significantly correlated with diabetes-related variables (e.g. duration and cumulative glycaemic control of the disease) and concurrent diabetic microangiopathy. Male sex was associated with higher values of the 'heat-related' factor, while the 'hand sensation' factor did not correlate with any of the study variables.
Conclusions: The distribution of the various thermal and vibration threshold variables according to the three factors may point at length-dependent mechanism of axonal degeneration. Cold, warmth and vibration perception thresholds in the foot may be the only valuable psychophysical parameters in the evaluation of early sensory impairment associated with diabetes.