Figure 1.

People with T2DM have higher chromatic thresholds. Chromatic thresholds were measured in the undilated right eyes of 20 healthy controls (HbA1c ≤ 5.6%), 13 participants with PreDM (HbA1c = 5.7%–6.4%), and 15 participants with T2DM (HbA1c ≥ 6.5%). (A, B, D, E) Within-group average thresholds (logCC) across the four positions tested for the red, green, blue, and yellow stimuli, respectively, during different segments of the test. (C, F) Thresholds obtained from the red and green stimuli were averaged (C), as were those from the blue and yellow stimuli (F), to assess potential selective involvement of the parvocellular and koniocellular pathways, respectively, in the pathophysiology of PreDM and T2DM. Numbers on the plots represent the adjusted P values. Adjusted P < 0.05 was considered statistically significant.