Background: P300 event-related potentials can be used to measure auditory processing speed, working memory and attention.
Purpose: The purpose of the study was to compare latencies and amplitudes of the P300 event-related potentials in normal hearing adults with the latencies and amplitudes of participants diagnosed with type II Diabetes Mellitus (DM).
Research design: A two group (with diabetes and controls) comparative study (age- and sex-matched) with a non-probability sampling method was used.
Study sample: Sixty-four participants (32 adults with diabetes, 32 adults without diabetes) between the ages of 23 to 60 years participated (M 47.50 years, 10).
Data collection and analysis: Pure tone audiometry was performed to ensure participants had a pure tone average of ≤ 25 dB HL. The Folstein Mini-Mental State Examination was conducted which ensured participants had no cognitive impairment. Blood glucose levels were measured immediately prior to P300 testing. Amplitude and latency results were captured for the P300 test. Descriptive analysis was used to calculate the mean, standard deviation, as well as the median and 25th and 75th percentiles. In order to study the differences between adults with and without diabetes as well the effect of glucose, linear mixed model regression analyses were performed when left and right ears were combined, and simple linear regression when left and right ears were analysed separately.
Results: For the P300 latency results, a significant statistical difference (p˂0.001) was observed between the participants with diabetes (352.46 ms, SD 36.36) and participants without diabetes (314.09 ms, SD 32.08). A significant statistical difference (p˂0.001) in amplitude was also observed between the participants with diabetes (12.10 μV, SD 3.70) and participants without diabetes (15.08 μV, SD 2.82). Glucose was a key moderator of amplitude but not latency after adjusting for diabetes status. Glucose had no effect on amplitude and latency for adults without type II DM. Conclusions: It was found that type II DM decreases P300 amplitude and increases latency. In adults with type II DM, attention and working memory, as denoted by P300 amplitude, may deteriorate with an increase in glucose levels on the day of testing.